exchangelib.restriction API documentation

# Module `exchangelib.restriction`

Expand source code

    import logging
    from collections import OrderedDict
    from copy import copy

    from .fields import InvalidField, FieldPath, DateTimeBackedDateField
    from .util import create_element, xml_to_str, value_to_xml_text, is_iterable
    from .version import EXCHANGE_2010

    log = logging.getLogger(__name__)

    class Q:
        """A class with an API similar to Django Q objects. Used to implemnt advanced filtering logic."""

        # Connection types
        AND = 'AND'
        OR = 'OR'
        NOT = 'NOT'
        NEVER = 'NEVER'  # This is not specified by EWS. We use it for queries that will never match, e.g. 'foo__in=()'
        CONN_TYPES = {AND, OR, NOT, NEVER}

        # EWS Operators
        EQ = '=='
        NE = '!='
        GT = '>'
        GTE = '>='
        LT = '<'
        LTE = '<='
        EXACT = 'exact'
        IEXACT = 'iexact'
        CONTAINS = 'contains'
        ICONTAINS = 'icontains'
        STARTSWITH = 'startswith'
        ISTARTSWITH = 'istartswith'
        EXISTS = 'exists'
        OP_TYPES = {EQ, NE, GT, GTE, LT, LTE, EXACT, IEXACT, CONTAINS, ICONTAINS, STARTSWITH, ISTARTSWITH, EXISTS}
        CONTAINS_OPS = {EXACT, IEXACT, CONTAINS, ICONTAINS, STARTSWITH, ISTARTSWITH}

        # Valid lookups
        LOOKUP_RANGE = 'range'
        LOOKUP_IN = 'in'
        LOOKUP_NOT = 'not'
        LOOKUP_GT = 'gt'
        LOOKUP_GTE = 'gte'
        LOOKUP_LT = 'lt'
        LOOKUP_LTE = 'lte'
        LOOKUP_EXACT = 'exact'
        LOOKUP_IEXACT = 'iexact'
        LOOKUP_CONTAINS = 'contains'
        LOOKUP_ICONTAINS = 'icontains'
        LOOKUP_STARTSWITH = 'startswith'
        LOOKUP_ISTARTSWITH = 'istartswith'
        LOOKUP_EXISTS = 'exists'
        LOOKUP_TYPES = {LOOKUP_RANGE, LOOKUP_IN, LOOKUP_NOT, LOOKUP_GT, LOOKUP_GTE, LOOKUP_LT, LOOKUP_LTE, LOOKUP_EXACT,
                        LOOKUP_IEXACT, LOOKUP_CONTAINS, LOOKUP_ICONTAINS, LOOKUP_STARTSWITH, LOOKUP_ISTARTSWITH,
                        LOOKUP_EXISTS}

        __slots__ = 'conn_type', 'field_path', 'op', 'value', 'children', 'query_string'

        def __init__(self, *args, **kwargs):
            self.conn_type = kwargs.pop('conn_type', self.AND)

            self.field_path = None  # Name of the field we want to filter on
            self.op = None
            self.value = None
            self.query_string = None

            # Parsing of args and kwargs may require child elements
            self.children = []

            # Check for query string as the only argument
            if not kwargs and len(args) == 1 and isinstance(args[0], str):
                self.query_string = args[0]
                args = ()

            # Parse args which must now be Q objects
            for q in args:
                if not isinstance(q, self.__class__):
                    raise ValueError("Non-keyword arg %r must be a Q instance" % q)
            self.children.extend(args)

            # Parse keyword args and extract the filter
            is_single_kwarg = len(args) == 0 and len(kwargs) == 1
            for key, value in kwargs.items():
                self.children.extend(
                    self._get_children_from_kwarg(key=key, value=value, is_single_kwarg=is_single_kwarg)
                )

            # Simplify this object
            self.reduce()

            # Final sanity check
            self._check_integrity()

        def _get_children_from_kwarg(self, key, value, is_single_kwarg=False):
            """Generate Q objects corresponding to a single keyword argument. Make this a leaf if there are no children to
            generate.
            """
            key_parts = key.rsplit('__', 1)
            if len(key_parts) == 2 and key_parts[1] in self.LOOKUP_TYPES:
                # This is a kwarg with a lookup at the end
                field_path, lookup = key_parts
                if lookup == self.LOOKUP_EXISTS:
                    # value=True will fall through to further processing
                    if not value:
                        return [~self.__class__(**{key: True})]

                if lookup == self.LOOKUP_RANGE:
                    # EWS doesn't have a 'range' operator. Emulate 'foo__range=(1, 2)' as 'foo__gte=1 and foo__lte=2'
                    # (both values inclusive).
                    if len(value) != 2:
                        raise ValueError("Value of lookup '%s' must have exactly 2 elements" % key)
                    return [
                        self.__class__(**{'%s__gte' % field_path: value[0]}),
                        self.__class__(**{'%s__lte' % field_path: value[1]}),
                    ]

                # Filtering on list types is a bit quirky. The only lookup type I have found to work is:
                #
                #     item:Categories == 'foo' AND item:Categories == 'bar' AND ...
                #
                #     item:Categories == 'foo' OR item:Categories == 'bar' OR ...
                #
                # The former returns items that have all these categories, but maybe also others. The latter returns
                # items that have at least one of these categories. This translates to the 'contains' and 'in' lookups,
                # respectively. Both versions are case-insensitive.
                #
                # Exact matching and case-sensitive or partial-string matching is not possible since that requires the
                # 'Contains' element which only supports matching on string elements, not arrays.
                #
                # Exact matching of categories (i.e. match ['a', 'b'] but not ['a', 'b', 'c']) could be implemented by
                # post-processing items by fetch the categories field unconditionally and removing the items that don't
                # have an exact match.
                if lookup == self.LOOKUP_IN:
                    # EWS doesn't have an '__in' operator. Allow '__in' lookups on list and non-list field types,
                    # specifying a list value. We'll emulate it as a set of OR'ed exact matches.
                    if not is_iterable(value, generators_allowed=True):
                        raise ValueError("Value for lookup %r must be a list" % key)
                    children = [self.__class__(**{field_path: v}) for v in value]
                    if not children:
                        # This is an '__in' operator with an empty list as the value. We interpret it to mean "is foo
                        # contained in the empty set?" which is always false. Mark this Q object as such.
                        return [self.__class__(conn_type=self.NEVER)]
                    return [self.__class__(*children, conn_type=self.OR)]

                if lookup == self.LOOKUP_CONTAINS and is_iterable(value, generators_allowed=True):
                    # A '__contains' lookup with an list as the value ony makes sense for list fields, since exact match
                    # on multiple distinct values will always fail for single-value fields.
                    #
                    # An empty list as value is allowed. We interpret it to mean "are all values in the empty set contained
                    # in foo?" which is always true.
                    children = [self.__class__(**{field_path: v}) for v in value]
                    return [self.__class__(*children, conn_type=self.AND)]

                try:
                    op = self._lookup_to_op(lookup)
                except KeyError:
                    raise ValueError("Lookup '%s' is not supported (called as '%s=%r')" % (lookup, key, value))
            else:
                field_path, op = key, self.EQ

            if not is_single_kwarg:
                return [self.__class__(**{key: value})]

            # This is a single-kwarg Q object with a lookup that requires a single value. Make this a leaf
            self.field_path = field_path
            self.op = op
            self.value = value
            return []

        def reduce(self):
            """Simplify this object, if possible."""
            self._reduce_children()
            self._promote()

        def _reduce_children(self):
            """Look at the children of this object and remove unnecessary items."""
            children = self.children
            if any((isinstance(a, self.__class__) and a.is_never()) for a in children):
                # We have at least one 'never' arg
                if self.conn_type == self.AND:
                    # Remove all other args since nothing we AND together with a 'never' arg can change the result
                    children = [self.__class__(conn_type=self.NEVER)]
                elif self.conn_type == self.OR:
                    # Remove all 'never' args because all other args will decide the result. Keep one 'never' arg in case
                    # all args are 'never' args.
                    children = [a for a in children if not (isinstance(a, self.__class__) and a.is_never())]
                    if not children:
                        children = [self.__class__(conn_type=self.NEVER)]
                elif self.conn_type == self.NOT:
                    # Let's interpret 'not never' to mean 'always'. Remove all 'never' args
                    children = [a for a in children if not (isinstance(a, self.__class__) and a.is_never())]

            # Remove any empty Q elements in args before proceeding
            children = [a for a in children if not (isinstance(a, self.__class__) and a.is_empty())]
            self.children = children

        def _promote(self):
            """When we only have one child and no expression on ourselves, we are a no-op. Flatten by taking over the only
            child.
            """
            if len(self.children) != 1 or self.field_path is not None or self.conn_type == self.NOT:
                return

            q = self.children[0]
            self.conn_type = q.conn_type
            self.field_path = q.field_path
            self.op = q.op
            self.value = q.value
            self.query_string = q.query_string
            self.children = q.children

        def clean(self, version):
            """Do some basic checks on the attributes, using a generic folder. to_xml() does a really good job of
            validating. There's no reason to replicate much of that here.
            """
            from .folders import Folder
            self.to_xml(folders=[Folder()], version=version, applies_to=Restriction.ITEMS)

        @classmethod
        def _lookup_to_op(cls, lookup):
            return {
                cls.LOOKUP_NOT: cls.NE,
                cls.LOOKUP_GT: cls.GT,
                cls.LOOKUP_GTE: cls.GTE,
                cls.LOOKUP_LT: cls.LT,
                cls.LOOKUP_LTE: cls.LTE,
                cls.LOOKUP_EXACT: cls.EXACT,
                cls.LOOKUP_IEXACT: cls.IEXACT,
                cls.LOOKUP_CONTAINS: cls.CONTAINS,
                cls.LOOKUP_ICONTAINS: cls.ICONTAINS,
                cls.LOOKUP_STARTSWITH: cls.STARTSWITH,
                cls.LOOKUP_ISTARTSWITH: cls.ISTARTSWITH,
                cls.LOOKUP_EXISTS: cls.EXISTS,
            }[lookup]

        @classmethod
        def _conn_to_xml(cls, conn_type):
            xml_tag_map = {
                cls.AND: 't:And',
                cls.OR: 't:Or',
                cls.NOT: 't:Not',
            }
            return create_element(xml_tag_map[conn_type])

        @classmethod
        def _op_to_xml(cls, op):
            xml_tag_map = {
                cls.EQ: 't:IsEqualTo',
                cls.NE: 't:IsNotEqualTo',
                cls.GTE: 't:IsGreaterThanOrEqualTo',
                cls.LTE: 't:IsLessThanOrEqualTo',
                cls.LT: 't:IsLessThan',
                cls.GT: 't:IsGreaterThan',
                cls.EXISTS: 't:Exists',
            }
            if op in xml_tag_map:
                return create_element(xml_tag_map[op])
            valid_ops = cls.EXACT, cls.IEXACT, cls.CONTAINS, cls.ICONTAINS, cls.STARTSWITH, cls.ISTARTSWITH
            if op not in valid_ops:
                raise ValueError("'op' %s must be one of %s" % (op, valid_ops))

            # For description of Contains attribute values, see
            #     https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/contains
            #
            # Possible ContainmentMode values:
            #     FullString, Prefixed, Substring, PrefixOnWords, ExactPhrase
            # Django lookups have no equivalent of PrefixOnWords and ExactPhrase (and I'm unsure how they actually
            # work).
            #
            # EWS has no equivalent of '__endswith' or '__iendswith'. That could be emulated using '__contains' and
            # '__icontains' and filtering results afterwards in Python. But it could be inefficient because we might be
            # fetching and discarding a lot of non-matching items, plus we would need to always fetch the field we're
            # matching on, to be able to do the filtering. I think it's better to leave this to the consumer, i.e.:
            #
            # items = [i for i in fld.filter(subject__contains=suffix) if i.subject.endswith(suffix)]
            # items = [i for i in fld.filter(subject__icontains=suffix) if i.subject.lower().endswith(suffix.lower())]
            #
            # Possible ContainmentComparison values (there are more, but the rest are "To be removed"):
            #     Exact, IgnoreCase, IgnoreNonSpacingCharacters, IgnoreCaseAndNonSpacingCharacters
            # I'm unsure about non-spacing characters, but as I read
            #    https://en.wikipedia.org/wiki/Graphic_character#Spacing_and_non-spacing_characters
            # we shouldn't ignore them ('a' would match both 'a' and 'å', the latter having a non-spacing character).
            if op in {cls.EXACT, cls.IEXACT}:
                match_mode = 'FullString'
            elif op in (cls.CONTAINS, cls.ICONTAINS):
                match_mode = 'Substring'
            elif op in (cls.STARTSWITH, cls.ISTARTSWITH):
                match_mode = 'Prefixed'
            else:
                raise ValueError('Unsupported op: %s' % op)
            if op in (cls.IEXACT, cls.ICONTAINS, cls.ISTARTSWITH):
                compare_mode = 'IgnoreCase'
            else:
                compare_mode = 'Exact'
            return create_element(
                't:Contains',
                attrs=OrderedDict([
                    ('ContainmentMode', match_mode),
                    ('ContainmentComparison', compare_mode),
                ])
            )

        def is_leaf(self):
            return not self.children

        def is_empty(self):
            """Return True if this object is without any restrictions at all."""
            return self.is_leaf() and self.field_path is None and self.query_string is None and self.conn_type != self.NEVER

        def is_never(self):
            """Return True if this object has a restriction that will never match anything."""
            return self.conn_type == self.NEVER

        def expr(self):
            if self.is_empty():
                return None
            if self.is_never():
                return self.NEVER
            if self.query_string:
                return self.query_string
            if self.is_leaf():
                expr = '%s %s %r' % (self.field_path, self.op, self.value)
            else:
                # Sort children by field name so we get stable output (for easier testing). Children should never be empty.
                expr = (' %s ' % (self.AND if self.conn_type == self.NOT else self.conn_type)).join(
                    (c.expr() if c.is_leaf() or c.conn_type == self.NOT else '(%s)' % c.expr())
                    for c in sorted(self.children, key=lambda i: i.field_path or '')
                )
            if self.conn_type == self.NOT:
                # Add the NOT operator. Put children in parens if there is more than one child.
                if self.is_leaf() or len(self.children) == 1:
                    return self.conn_type + ' %s' % expr
                return self.conn_type + ' (%s)' % expr
            return expr

        def to_xml(self, folders, version, applies_to):
            if self.query_string:
                self._check_integrity()
                if version.build < EXCHANGE_2010:
                    raise NotImplementedError('QueryString filtering is only supported for Exchange 2010 servers and later')
                elem = create_element('m:QueryString')
                elem.text = self.query_string
                return elem
            # Translate this Q object to a valid Restriction XML tree
            elem = self.xml_elem(folders=folders, version=version, applies_to=applies_to)
            if elem is None:
                return None
            restriction = create_element('m:Restriction')
            restriction.append(elem)
            return restriction

        def _check_integrity(self):
            if self.is_empty():
                return
            if self.conn_type == self.NEVER:
                if any([self.field_path, self.op, self.value, self.children]):
                    raise ValueError("'never' queries cannot be combined with other settings")
                return
            if self.query_string:
                if any([self.field_path, self.op, self.value, self.children]):
                    raise ValueError('Query strings cannot be combined with other settings')
                return
            if self.conn_type not in self.CONN_TYPES:
                raise ValueError("'conn_type' %s must be one of %s" % (self.conn_type, self.CONN_TYPES))
            if not self.is_leaf():
                for q in self.children:
                    if q.query_string and len(self.children) > 1:
                        raise ValueError(
                            'A query string cannot be combined with other restrictions'
                        )
                return
            if not self.field_path:
                raise ValueError("'field_path' must be set")
            if self.op not in self.OP_TYPES:
                raise ValueError("'op' %s must be one of %s" % (self.op, self.OP_TYPES))
            if self.op == self.EXISTS and self.value is not True:
                raise ValueError("'value' must be True when operator is EXISTS")
            if self.value is None:
                raise ValueError('Value for filter on field path "%s" cannot be None' % self.field_path)
            if is_iterable(self.value, generators_allowed=True):
                raise ValueError(
                    'Value %r for filter on field path "%s" must be a single value' % (self.value, self.field_path)
                )

        def _validate_field_path(self, field_path, folder, applies_to, version):
            from .indexed_properties import MultiFieldIndexedElement
            if applies_to == Restriction.FOLDERS:
                # This is a restriction on Folder fields
                folder.validate_field(field=field_path.field, version=version)
            else:
                folder.validate_item_field(field=field_path.field, version=version)
            if not field_path.field.is_searchable:
                raise ValueError("EWS does not support filtering on field '%s'" % field_path.field.name)
            if field_path.subfield and not field_path.subfield.is_searchable:
                raise ValueError("EWS does not support filtering on subfield '%s'" % field_path.subfield.name)
            if issubclass(field_path.field.value_cls, MultiFieldIndexedElement) and not field_path.subfield:
                raise ValueError("Field path '%s' must contain a subfield" % self.field_path)

        def _get_field_path(self, folders, applies_to, version):
            # Convert the string field path to a real FieldPath object. The path is validated using the given folders.
            for folder in folders:
                try:
                    if applies_to == Restriction.FOLDERS:
                        # This is a restriction on Folder fields
                        field = folder.get_field_by_fieldname(fieldname=self.field_path)
                        field_path = FieldPath(field=field)
                    else:
                        field_path = FieldPath.from_string(field_path=self.field_path, folder=folder)
                except ValueError:
                    continue
                self._validate_field_path(field_path=field_path, folder=folder, applies_to=applies_to, version=version)
                break
            else:
                raise InvalidField("Unknown field path %r on folders %s" % (self.field_path, folders))
            return field_path

        def _get_clean_value(self, field_path, version):
            if self.op == self.EXISTS:
                return None
            clean_field = field_path.subfield if (field_path.subfield and field_path.label) else field_path.field
            if clean_field.is_list:
                # __contains and __in are implemented as multiple leaves, with one value per leaf. clean() on list fields
                # only works on lists, so clean a one-element list.
                return clean_field.clean(value=[self.value], version=version)[0]
            return clean_field.clean(value=self.value, version=version)

        def xml_elem(self, folders, version, applies_to):
            # Recursively build an XML tree structure of this Q object. If this is an empty leaf (the equivalent of Q()),
            # return None.
            from .indexed_properties import SingleFieldIndexedElement
            # Don't check self.value just yet. We want to return error messages on the field path first, and then the value.
            # This is done in _get_field_path() and _get_clean_value(), respectively.
            self._check_integrity()
            if self.is_empty():
                return None
            if self.is_never():
                raise ValueError("EWS does not support 'never' queries")
            if self.is_leaf():
                elem = self._op_to_xml(self.op)
                field_path = self._get_field_path(folders, applies_to=applies_to, version=version)
                clean_value = self._get_clean_value(field_path=field_path, version=version)
                if issubclass(field_path.field.value_cls, SingleFieldIndexedElement) and not field_path.label:
                    # We allow a filter shortcut of e.g. email_addresses__contains=EmailAddress(label='Foo', ...) instead of
                    # email_addresses__Foo_email_address=.... Set FieldPath label now so we can generate the field_uri.
                    field_path.label = clean_value.label
                elif isinstance(field_path.field, DateTimeBackedDateField):
                    # We need to convert to datetime
                    clean_value = field_path.field.date_to_datetime(clean_value)
                elem.append(field_path.to_xml())
                constant = create_element('t:Constant')
                if self.op != self.EXISTS:
                    # Use .set() to not fill up the create_element() cache with unique values
                    constant.set('Value', value_to_xml_text(clean_value))
                    if self.op in self.CONTAINS_OPS:
                        elem.append(constant)
                    else:
                        uriorconst = create_element('t:FieldURIOrConstant')
                        uriorconst.append(constant)
                        elem.append(uriorconst)
            elif len(self.children) == 1:
                # We have only one child
                elem = self.children[0].xml_elem(folders=folders, version=version, applies_to=applies_to)
            else:
                # We have multiple children. If conn_type is NOT, then group children with AND. We'll add the NOT later
                elem = self._conn_to_xml(self.AND if self.conn_type == self.NOT else self.conn_type)
                # Sort children by field name so we get stable output (for easier testing). Children should never be empty
                for c in sorted(self.children, key=lambda i: i.field_path or ''):
                    elem.append(c.xml_elem(folders=folders, version=version, applies_to=applies_to))
            if elem is None:
                return None  # Should not be necessary, but play safe
            if self.conn_type == self.NOT:
                # Encapsulate everything in the NOT element
                not_elem = self._conn_to_xml(self.conn_type)
                not_elem.append(elem)
                return not_elem
            return elem

        def __and__(self, other):
            # & operator. Return a new Q with two children and conn_type AND
            return self.__class__(self, other, conn_type=self.AND)

        def __or__(self, other):
            # | operator. Return a new Q with two children and conn_type OR
            return self.__class__(self, other, conn_type=self.OR)

        def __invert__(self):
            # ~ operator. If op has an inverse, change op. Else return a new Q with conn_type NOT
            if self.conn_type == self.NOT:
                # This is NOT NOT. Change to AND
                new = copy(self)
                new.conn_type = self.AND
                new.reduce()
                return new
            if self.is_leaf():
                inverse_ops = {
                    self.EQ: self.NE,
                    self.NE: self.EQ,
                    self.GT: self.LTE,
                    self.GTE: self.LT,
                    self.LT: self.GTE,
                    self.LTE: self.GT,
                }
                try:
                    new = copy(self)
                    new.op = inverse_ops[self.op]
                    new.reduce()
                    return new
                except KeyError:
                    pass
            return self.__class__(self, conn_type=self.NOT)

        def __eq__(self, other):
            return repr(self) == repr(other)

        def __hash__(self):
            return hash(repr(self))

        def __str__(self):
            return self.expr() or 'Q()'

        def __repr__(self):
            if self.is_leaf():
                if self.query_string:
                    return self.__class__.__name__ + '(%r)' % self.query_string
                if self.is_never():
                    return self.__class__.__name__ + '(conn_type=%r)' % (self.conn_type)
                return self.__class__.__name__ + '(%s %s %r)' % (self.field_path, self.op, self.value)
            sorted_children = tuple(sorted(self.children, key=lambda i: i.field_path or ''))
            if self.conn_type == self.NOT or len(self.children) > 1:
                return self.__class__.__name__ + repr((self.conn_type,) + sorted_children)
            return self.__class__.__name__ + repr(sorted_children)

    class Restriction:
        """Implement an EWS Restriction type."""

        # The type of item the restriction applies to
        FOLDERS = 'folders'
        ITEMS = 'items'
        RESTRICTION_TYPES = (FOLDERS, ITEMS)

        def __init__(self, q, folders, applies_to):
            if not isinstance(q, Q):
                raise ValueError("'q' value %r must be a Q instance" % q)
            if q.is_empty():
                raise ValueError("Q object must not be empty")
            from .folders import BaseFolder
            for folder in folders:
                if not isinstance(folder, BaseFolder):
                    raise ValueError("'folder' value %r must be a Folder instance" % folder)
            if applies_to not in self.RESTRICTION_TYPES:
                raise ValueError("'applies_to' must be one of %s" % (self.RESTRICTION_TYPES,))
            self.q = q
            self.folders = folders
            self.applies_to = applies_to

        def to_xml(self, version):
            return self.q.to_xml(folders=self.folders, version=version, applies_to=self.applies_to)

        def __str__(self):
            """Print the XML syntax tree."""
            return xml_to_str(self.to_xml(version=self.folders[0].account.version))

## Classes

`class Q (*args, **kwargs)`

  A class with an API similar to Django Q objects. Used to implemnt advanced filtering logic.

  Expand source code

      class Q:
          """A class with an API similar to Django Q objects. Used to implemnt advanced filtering logic."""

          # Connection types
          AND = 'AND'
          OR = 'OR'
          NOT = 'NOT'
          NEVER = 'NEVER'  # This is not specified by EWS. We use it for queries that will never match, e.g. 'foo__in=()'
          CONN_TYPES = {AND, OR, NOT, NEVER}

          # EWS Operators
          EQ = '=='
          NE = '!='
          GT = '>'
          GTE = '>='
          LT = '<'
          LTE = '<='
          EXACT = 'exact'
          IEXACT = 'iexact'
          CONTAINS = 'contains'
          ICONTAINS = 'icontains'
          STARTSWITH = 'startswith'
          ISTARTSWITH = 'istartswith'
          EXISTS = 'exists'
          OP_TYPES = {EQ, NE, GT, GTE, LT, LTE, EXACT, IEXACT, CONTAINS, ICONTAINS, STARTSWITH, ISTARTSWITH, EXISTS}
          CONTAINS_OPS = {EXACT, IEXACT, CONTAINS, ICONTAINS, STARTSWITH, ISTARTSWITH}

          # Valid lookups
          LOOKUP_RANGE = 'range'
          LOOKUP_IN = 'in'
          LOOKUP_NOT = 'not'
          LOOKUP_GT = 'gt'
          LOOKUP_GTE = 'gte'
          LOOKUP_LT = 'lt'
          LOOKUP_LTE = 'lte'
          LOOKUP_EXACT = 'exact'
          LOOKUP_IEXACT = 'iexact'
          LOOKUP_CONTAINS = 'contains'
          LOOKUP_ICONTAINS = 'icontains'
          LOOKUP_STARTSWITH = 'startswith'
          LOOKUP_ISTARTSWITH = 'istartswith'
          LOOKUP_EXISTS = 'exists'
          LOOKUP_TYPES = {LOOKUP_RANGE, LOOKUP_IN, LOOKUP_NOT, LOOKUP_GT, LOOKUP_GTE, LOOKUP_LT, LOOKUP_LTE, LOOKUP_EXACT,
                          LOOKUP_IEXACT, LOOKUP_CONTAINS, LOOKUP_ICONTAINS, LOOKUP_STARTSWITH, LOOKUP_ISTARTSWITH,
                          LOOKUP_EXISTS}

          __slots__ = 'conn_type', 'field_path', 'op', 'value', 'children', 'query_string'

          def __init__(self, *args, **kwargs):
              self.conn_type = kwargs.pop('conn_type', self.AND)

              self.field_path = None  # Name of the field we want to filter on
              self.op = None
              self.value = None
              self.query_string = None

              # Parsing of args and kwargs may require child elements
              self.children = []

              # Check for query string as the only argument
              if not kwargs and len(args) == 1 and isinstance(args[0], str):
                  self.query_string = args[0]
                  args = ()

              # Parse args which must now be Q objects
              for q in args:
                  if not isinstance(q, self.__class__):
                      raise ValueError("Non-keyword arg %r must be a Q instance" % q)
              self.children.extend(args)

              # Parse keyword args and extract the filter
              is_single_kwarg = len(args) == 0 and len(kwargs) == 1
              for key, value in kwargs.items():
                  self.children.extend(
                      self._get_children_from_kwarg(key=key, value=value, is_single_kwarg=is_single_kwarg)
                  )

              # Simplify this object
              self.reduce()

              # Final sanity check
              self._check_integrity()

          def _get_children_from_kwarg(self, key, value, is_single_kwarg=False):
              """Generate Q objects corresponding to a single keyword argument. Make this a leaf if there are no children to
              generate.
              """
              key_parts = key.rsplit('__', 1)
              if len(key_parts) == 2 and key_parts[1] in self.LOOKUP_TYPES:
                  # This is a kwarg with a lookup at the end
                  field_path, lookup = key_parts
                  if lookup == self.LOOKUP_EXISTS:
                      # value=True will fall through to further processing
                      if not value:
                          return [~self.__class__(**{key: True})]

                  if lookup == self.LOOKUP_RANGE:
                      # EWS doesn't have a 'range' operator. Emulate 'foo__range=(1, 2)' as 'foo__gte=1 and foo__lte=2'
                      # (both values inclusive).
                      if len(value) != 2:
                          raise ValueError("Value of lookup '%s' must have exactly 2 elements" % key)
                      return [
                          self.__class__(**{'%s__gte' % field_path: value[0]}),
                          self.__class__(**{'%s__lte' % field_path: value[1]}),
                      ]

                  # Filtering on list types is a bit quirky. The only lookup type I have found to work is:
                  #
                  #     item:Categories == 'foo' AND item:Categories == 'bar' AND ...
                  #
                  #     item:Categories == 'foo' OR item:Categories == 'bar' OR ...
                  #
                  # The former returns items that have all these categories, but maybe also others. The latter returns
                  # items that have at least one of these categories. This translates to the 'contains' and 'in' lookups,
                  # respectively. Both versions are case-insensitive.
                  #
                  # Exact matching and case-sensitive or partial-string matching is not possible since that requires the
                  # 'Contains' element which only supports matching on string elements, not arrays.
                  #
                  # Exact matching of categories (i.e. match ['a', 'b'] but not ['a', 'b', 'c']) could be implemented by
                  # post-processing items by fetch the categories field unconditionally and removing the items that don't
                  # have an exact match.
                  if lookup == self.LOOKUP_IN:
                      # EWS doesn't have an '__in' operator. Allow '__in' lookups on list and non-list field types,
                      # specifying a list value. We'll emulate it as a set of OR'ed exact matches.
                      if not is_iterable(value, generators_allowed=True):
                          raise ValueError("Value for lookup %r must be a list" % key)
                      children = [self.__class__(**{field_path: v}) for v in value]
                      if not children:
                          # This is an '__in' operator with an empty list as the value. We interpret it to mean "is foo
                          # contained in the empty set?" which is always false. Mark this Q object as such.
                          return [self.__class__(conn_type=self.NEVER)]
                      return [self.__class__(*children, conn_type=self.OR)]

                  if lookup == self.LOOKUP_CONTAINS and is_iterable(value, generators_allowed=True):
                      # A '__contains' lookup with an list as the value ony makes sense for list fields, since exact match
                      # on multiple distinct values will always fail for single-value fields.
                      #
                      # An empty list as value is allowed. We interpret it to mean "are all values in the empty set contained
                      # in foo?" which is always true.
                      children = [self.__class__(**{field_path: v}) for v in value]
                      return [self.__class__(*children, conn_type=self.AND)]

                  try:
                      op = self._lookup_to_op(lookup)
                  except KeyError:
                      raise ValueError("Lookup '%s' is not supported (called as '%s=%r')" % (lookup, key, value))
              else:
                  field_path, op = key, self.EQ

              if not is_single_kwarg:
                  return [self.__class__(**{key: value})]

              # This is a single-kwarg Q object with a lookup that requires a single value. Make this a leaf
              self.field_path = field_path
              self.op = op
              self.value = value
              return []

          def reduce(self):
              """Simplify this object, if possible."""
              self._reduce_children()
              self._promote()

          def _reduce_children(self):
              """Look at the children of this object and remove unnecessary items."""
              children = self.children
              if any((isinstance(a, self.__class__) and a.is_never()) for a in children):
                  # We have at least one 'never' arg
                  if self.conn_type == self.AND:
                      # Remove all other args since nothing we AND together with a 'never' arg can change the result
                      children = [self.__class__(conn_type=self.NEVER)]
                  elif self.conn_type == self.OR:
                      # Remove all 'never' args because all other args will decide the result. Keep one 'never' arg in case
                      # all args are 'never' args.
                      children = [a for a in children if not (isinstance(a, self.__class__) and a.is_never())]
                      if not children:
                          children = [self.__class__(conn_type=self.NEVER)]
                  elif self.conn_type == self.NOT:
                      # Let's interpret 'not never' to mean 'always'. Remove all 'never' args
                      children = [a for a in children if not (isinstance(a, self.__class__) and a.is_never())]

              # Remove any empty Q elements in args before proceeding
              children = [a for a in children if not (isinstance(a, self.__class__) and a.is_empty())]
              self.children = children

          def _promote(self):
              """When we only have one child and no expression on ourselves, we are a no-op. Flatten by taking over the only
              child.
              """
              if len(self.children) != 1 or self.field_path is not None or self.conn_type == self.NOT:
                  return

              q = self.children[0]
              self.conn_type = q.conn_type
              self.field_path = q.field_path
              self.op = q.op
              self.value = q.value
              self.query_string = q.query_string
              self.children = q.children

          def clean(self, version):
              """Do some basic checks on the attributes, using a generic folder. to_xml() does a really good job of
              validating. There's no reason to replicate much of that here.
              """
              from .folders import Folder
              self.to_xml(folders=[Folder()], version=version, applies_to=Restriction.ITEMS)

          @classmethod
          def _lookup_to_op(cls, lookup):
              return {
                  cls.LOOKUP_NOT: cls.NE,
                  cls.LOOKUP_GT: cls.GT,
                  cls.LOOKUP_GTE: cls.GTE,
                  cls.LOOKUP_LT: cls.LT,
                  cls.LOOKUP_LTE: cls.LTE,
                  cls.LOOKUP_EXACT: cls.EXACT,
                  cls.LOOKUP_IEXACT: cls.IEXACT,
                  cls.LOOKUP_CONTAINS: cls.CONTAINS,
                  cls.LOOKUP_ICONTAINS: cls.ICONTAINS,
                  cls.LOOKUP_STARTSWITH: cls.STARTSWITH,
                  cls.LOOKUP_ISTARTSWITH: cls.ISTARTSWITH,
                  cls.LOOKUP_EXISTS: cls.EXISTS,
              }[lookup]

          @classmethod
          def _conn_to_xml(cls, conn_type):
              xml_tag_map = {
                  cls.AND: 't:And',
                  cls.OR: 't:Or',
                  cls.NOT: 't:Not',
              }
              return create_element(xml_tag_map[conn_type])

          @classmethod
          def _op_to_xml(cls, op):
              xml_tag_map = {
                  cls.EQ: 't:IsEqualTo',
                  cls.NE: 't:IsNotEqualTo',
                  cls.GTE: 't:IsGreaterThanOrEqualTo',
                  cls.LTE: 't:IsLessThanOrEqualTo',
                  cls.LT: 't:IsLessThan',
                  cls.GT: 't:IsGreaterThan',
                  cls.EXISTS: 't:Exists',
              }
              if op in xml_tag_map:
                  return create_element(xml_tag_map[op])
              valid_ops = cls.EXACT, cls.IEXACT, cls.CONTAINS, cls.ICONTAINS, cls.STARTSWITH, cls.ISTARTSWITH
              if op not in valid_ops:
                  raise ValueError("'op' %s must be one of %s" % (op, valid_ops))

              # For description of Contains attribute values, see
              #     https://docs.microsoft.com/en-us/exchange/client-developer/web-service-reference/contains
              #
              # Possible ContainmentMode values:
              #     FullString, Prefixed, Substring, PrefixOnWords, ExactPhrase
              # Django lookups have no equivalent of PrefixOnWords and ExactPhrase (and I'm unsure how they actually
              # work).
              #
              # EWS has no equivalent of '__endswith' or '__iendswith'. That could be emulated using '__contains' and
              # '__icontains' and filtering results afterwards in Python. But it could be inefficient because we might be
              # fetching and discarding a lot of non-matching items, plus we would need to always fetch the field we're
              # matching on, to be able to do the filtering. I think it's better to leave this to the consumer, i.e.:
              #
              # items = [i for i in fld.filter(subject__contains=suffix) if i.subject.endswith(suffix)]
              # items = [i for i in fld.filter(subject__icontains=suffix) if i.subject.lower().endswith(suffix.lower())]
              #
              # Possible ContainmentComparison values (there are more, but the rest are "To be removed"):
              #     Exact, IgnoreCase, IgnoreNonSpacingCharacters, IgnoreCaseAndNonSpacingCharacters
              # I'm unsure about non-spacing characters, but as I read
              #    https://en.wikipedia.org/wiki/Graphic_character#Spacing_and_non-spacing_characters
              # we shouldn't ignore them ('a' would match both 'a' and 'å', the latter having a non-spacing character).
              if op in {cls.EXACT, cls.IEXACT}:
                  match_mode = 'FullString'
              elif op in (cls.CONTAINS, cls.ICONTAINS):
                  match_mode = 'Substring'
              elif op in (cls.STARTSWITH, cls.ISTARTSWITH):
                  match_mode = 'Prefixed'
              else:
                  raise ValueError('Unsupported op: %s' % op)
              if op in (cls.IEXACT, cls.ICONTAINS, cls.ISTARTSWITH):
                  compare_mode = 'IgnoreCase'
              else:
                  compare_mode = 'Exact'
              return create_element(
                  't:Contains',
                  attrs=OrderedDict([
                      ('ContainmentMode', match_mode),
                      ('ContainmentComparison', compare_mode),
                  ])
              )

          def is_leaf(self):
              return not self.children

          def is_empty(self):
              """Return True if this object is without any restrictions at all."""
              return self.is_leaf() and self.field_path is None and self.query_string is None and self.conn_type != self.NEVER

          def is_never(self):
              """Return True if this object has a restriction that will never match anything."""
              return self.conn_type == self.NEVER

          def expr(self):
              if self.is_empty():
                  return None
              if self.is_never():
                  return self.NEVER
              if self.query_string:
                  return self.query_string
              if self.is_leaf():
                  expr = '%s %s %r' % (self.field_path, self.op, self.value)
              else:
                  # Sort children by field name so we get stable output (for easier testing). Children should never be empty.
                  expr = (' %s ' % (self.AND if self.conn_type == self.NOT else self.conn_type)).join(
                      (c.expr() if c.is_leaf() or c.conn_type == self.NOT else '(%s)' % c.expr())
                      for c in sorted(self.children, key=lambda i: i.field_path or '')
                  )
              if self.conn_type == self.NOT:
                  # Add the NOT operator. Put children in parens if there is more than one child.
                  if self.is_leaf() or len(self.children) == 1:
                      return self.conn_type + ' %s' % expr
                  return self.conn_type + ' (%s)' % expr
              return expr

          def to_xml(self, folders, version, applies_to):
              if self.query_string:
                  self._check_integrity()
                  if version.build < EXCHANGE_2010:
                      raise NotImplementedError('QueryString filtering is only supported for Exchange 2010 servers and later')
                  elem = create_element('m:QueryString')
                  elem.text = self.query_string
                  return elem
              # Translate this Q object to a valid Restriction XML tree
              elem = self.xml_elem(folders=folders, version=version, applies_to=applies_to)
              if elem is None:
                  return None
              restriction = create_element('m:Restriction')
              restriction.append(elem)
              return restriction

          def _check_integrity(self):
              if self.is_empty():
                  return
              if self.conn_type == self.NEVER:
                  if any([self.field_path, self.op, self.value, self.children]):
                      raise ValueError("'never' queries cannot be combined with other settings")
                  return
              if self.query_string:
                  if any([self.field_path, self.op, self.value, self.children]):
                      raise ValueError('Query strings cannot be combined with other settings')
                  return
              if self.conn_type not in self.CONN_TYPES:
                  raise ValueError("'conn_type' %s must be one of %s" % (self.conn_type, self.CONN_TYPES))
              if not self.is_leaf():
                  for q in self.children:
                      if q.query_string and len(self.children) > 1:
                          raise ValueError(
                              'A query string cannot be combined with other restrictions'
                          )
                  return
              if not self.field_path:
                  raise ValueError("'field_path' must be set")
              if self.op not in self.OP_TYPES:
                  raise ValueError("'op' %s must be one of %s" % (self.op, self.OP_TYPES))
              if self.op == self.EXISTS and self.value is not True:
                  raise ValueError("'value' must be True when operator is EXISTS")
              if self.value is None:
                  raise ValueError('Value for filter on field path "%s" cannot be None' % self.field_path)
              if is_iterable(self.value, generators_allowed=True):
                  raise ValueError(
                      'Value %r for filter on field path "%s" must be a single value' % (self.value, self.field_path)
                  )

          def _validate_field_path(self, field_path, folder, applies_to, version):
              from .indexed_properties import MultiFieldIndexedElement
              if applies_to == Restriction.FOLDERS:
                  # This is a restriction on Folder fields
                  folder.validate_field(field=field_path.field, version=version)
              else:
                  folder.validate_item_field(field=field_path.field, version=version)
              if not field_path.field.is_searchable:
                  raise ValueError("EWS does not support filtering on field '%s'" % field_path.field.name)
              if field_path.subfield and not field_path.subfield.is_searchable:
                  raise ValueError("EWS does not support filtering on subfield '%s'" % field_path.subfield.name)
              if issubclass(field_path.field.value_cls, MultiFieldIndexedElement) and not field_path.subfield:
                  raise ValueError("Field path '%s' must contain a subfield" % self.field_path)

          def _get_field_path(self, folders, applies_to, version):
              # Convert the string field path to a real FieldPath object. The path is validated using the given folders.
              for folder in folders:
                  try:
                      if applies_to == Restriction.FOLDERS:
                          # This is a restriction on Folder fields
                          field = folder.get_field_by_fieldname(fieldname=self.field_path)
                          field_path = FieldPath(field=field)
                      else:
                          field_path = FieldPath.from_string(field_path=self.field_path, folder=folder)
                  except ValueError:
                      continue
                  self._validate_field_path(field_path=field_path, folder=folder, applies_to=applies_to, version=version)
                  break
              else:
                  raise InvalidField("Unknown field path %r on folders %s" % (self.field_path, folders))
              return field_path

          def _get_clean_value(self, field_path, version):
              if self.op == self.EXISTS:
                  return None
              clean_field = field_path.subfield if (field_path.subfield and field_path.label) else field_path.field
              if clean_field.is_list:
                  # __contains and __in are implemented as multiple leaves, with one value per leaf. clean() on list fields
                  # only works on lists, so clean a one-element list.
                  return clean_field.clean(value=[self.value], version=version)[0]
              return clean_field.clean(value=self.value, version=version)

          def xml_elem(self, folders, version, applies_to):
              # Recursively build an XML tree structure of this Q object. If this is an empty leaf (the equivalent of Q()),
              # return None.
              from .indexed_properties import SingleFieldIndexedElement
              # Don't check self.value just yet. We want to return error messages on the field path first, and then the value.
              # This is done in _get_field_path() and _get_clean_value(), respectively.
              self._check_integrity()
              if self.is_empty():
                  return None
              if self.is_never():
                  raise ValueError("EWS does not support 'never' queries")
              if self.is_leaf():
                  elem = self._op_to_xml(self.op)
                  field_path = self._get_field_path(folders, applies_to=applies_to, version=version)
                  clean_value = self._get_clean_value(field_path=field_path, version=version)
                  if issubclass(field_path.field.value_cls, SingleFieldIndexedElement) and not field_path.label:
                      # We allow a filter shortcut of e.g. email_addresses__contains=EmailAddress(label='Foo', ...) instead of
                      # email_addresses__Foo_email_address=.... Set FieldPath label now so we can generate the field_uri.
                      field_path.label = clean_value.label
                  elif isinstance(field_path.field, DateTimeBackedDateField):
                      # We need to convert to datetime
                      clean_value = field_path.field.date_to_datetime(clean_value)
                  elem.append(field_path.to_xml())
                  constant = create_element('t:Constant')
                  if self.op != self.EXISTS:
                      # Use .set() to not fill up the create_element() cache with unique values
                      constant.set('Value', value_to_xml_text(clean_value))
                      if self.op in self.CONTAINS_OPS:
                          elem.append(constant)
                      else:
                          uriorconst = create_element('t:FieldURIOrConstant')
                          uriorconst.append(constant)
                          elem.append(uriorconst)
              elif len(self.children) == 1:
                  # We have only one child
                  elem = self.children[0].xml_elem(folders=folders, version=version, applies_to=applies_to)
              else:
                  # We have multiple children. If conn_type is NOT, then group children with AND. We'll add the NOT later
                  elem = self._conn_to_xml(self.AND if self.conn_type == self.NOT else self.conn_type)
                  # Sort children by field name so we get stable output (for easier testing). Children should never be empty
                  for c in sorted(self.children, key=lambda i: i.field_path or ''):
                      elem.append(c.xml_elem(folders=folders, version=version, applies_to=applies_to))
              if elem is None:
                  return None  # Should not be necessary, but play safe
              if self.conn_type == self.NOT:
                  # Encapsulate everything in the NOT element
                  not_elem = self._conn_to_xml(self.conn_type)
                  not_elem.append(elem)
                  return not_elem
              return elem

          def __and__(self, other):
              # & operator. Return a new Q with two children and conn_type AND
              return self.__class__(self, other, conn_type=self.AND)

          def __or__(self, other):
              # | operator. Return a new Q with two children and conn_type OR
              return self.__class__(self, other, conn_type=self.OR)

          def __invert__(self):
              # ~ operator. If op has an inverse, change op. Else return a new Q with conn_type NOT
              if self.conn_type == self.NOT:
                  # This is NOT NOT. Change to AND
                  new = copy(self)
                  new.conn_type = self.AND
                  new.reduce()
                  return new
              if self.is_leaf():
                  inverse_ops = {
                      self.EQ: self.NE,
                      self.NE: self.EQ,
                      self.GT: self.LTE,
                      self.GTE: self.LT,
                      self.LT: self.GTE,
                      self.LTE: self.GT,
                  }
                  try:
                      new = copy(self)
                      new.op = inverse_ops[self.op]
                      new.reduce()
                      return new
                  except KeyError:
                      pass
              return self.__class__(self, conn_type=self.NOT)

          def __eq__(self, other):
              return repr(self) == repr(other)

          def __hash__(self):
              return hash(repr(self))

          def __str__(self):
              return self.expr() or 'Q()'

          def __repr__(self):
              if self.is_leaf():
                  if self.query_string:
                      return self.__class__.__name__ + '(%r)' % self.query_string
                  if self.is_never():
                      return self.__class__.__name__ + '(conn_type=%r)' % (self.conn_type)
                  return self.__class__.__name__ + '(%s %s %r)' % (self.field_path, self.op, self.value)
              sorted_children = tuple(sorted(self.children, key=lambda i: i.field_path or ''))
              if self.conn_type == self.NOT or len(self.children) > 1:
                  return self.__class__.__name__ + repr((self.conn_type,) + sorted_children)
              return self.__class__.__name__ + repr(sorted_children)

  ### Class variables

  `var AND`
  `var CONN_TYPES`
  `var CONTAINS`
  `var CONTAINS_OPS`
  `var EQ`
  `var EXACT`
  `var EXISTS`
  `var GT`
  `var GTE`
  `var ICONTAINS`
  `var IEXACT`
  `var ISTARTSWITH`
  `var LOOKUP_CONTAINS`
  `var LOOKUP_EXACT`
  `var LOOKUP_EXISTS`
  `var LOOKUP_GT`
  `var LOOKUP_GTE`
  `var LOOKUP_ICONTAINS`
  `var LOOKUP_IEXACT`
  `var LOOKUP_IN`
  `var LOOKUP_ISTARTSWITH`
  `var LOOKUP_LT`
  `var LOOKUP_LTE`
  `var LOOKUP_NOT`
  `var LOOKUP_RANGE`
  `var LOOKUP_STARTSWITH`
  `var LOOKUP_TYPES`
  `var LT`
  `var LTE`
  `var NE`
  `var NEVER`
  `var NOT`
  `var OP_TYPES`
  `var OR`
  `var STARTSWITH`

  ### Instance variables

  `var children`

    Return an attribute of instance, which is of type owner.

  `var conn_type`

    Return an attribute of instance, which is of type owner.

  `var field_path`

    Return an attribute of instance, which is of type owner.

  `var op`

    Return an attribute of instance, which is of type owner.

  `var query_string`

    Return an attribute of instance, which is of type owner.

  `var value`

    Return an attribute of instance, which is of type owner.

  ### Methods

  `def clean(self, version)`

    Do some basic checks on the attributes, using a generic folder. to_xml() does a really good job of validating. There's no reason to replicate much of that here.

    Expand source code

        def clean(self, version):
            """Do some basic checks on the attributes, using a generic folder. to_xml() does a really good job of
            validating. There's no reason to replicate much of that here.
            """
            from .folders import Folder
            self.to_xml(folders=[Folder()], version=version, applies_to=Restriction.ITEMS)

  `def expr(self)`
    Expand source code

        def expr(self):
            if self.is_empty():
                return None
            if self.is_never():
                return self.NEVER
            if self.query_string:
                return self.query_string
            if self.is_leaf():
                expr = '%s %s %r' % (self.field_path, self.op, self.value)
            else:
                # Sort children by field name so we get stable output (for easier testing). Children should never be empty.
                expr = (' %s ' % (self.AND if self.conn_type == self.NOT else self.conn_type)).join(
                    (c.expr() if c.is_leaf() or c.conn_type == self.NOT else '(%s)' % c.expr())
                    for c in sorted(self.children, key=lambda i: i.field_path or '')
                )
            if self.conn_type == self.NOT:
                # Add the NOT operator. Put children in parens if there is more than one child.
                if self.is_leaf() or len(self.children) == 1:
                    return self.conn_type + ' %s' % expr
                return self.conn_type + ' (%s)' % expr
            return expr

  `def is_empty(self)`

    Return True if this object is without any restrictions at all.

    Expand source code

        def is_empty(self):
            """Return True if this object is without any restrictions at all."""
            return self.is_leaf() and self.field_path is None and self.query_string is None and self.conn_type != self.NEVER

  `def is_leaf(self)`
    Expand source code

        def is_leaf(self):
            return not self.children

  `def is_never(self)`

    Return True if this object has a restriction that will never match anything.

    Expand source code

        def is_never(self):
            """Return True if this object has a restriction that will never match anything."""
            return self.conn_type == self.NEVER

  `def reduce(self)`

    Simplify this object, if possible.

    Expand source code

        def reduce(self):
            """Simplify this object, if possible."""
            self._reduce_children()
            self._promote()

  `def to_xml(self, folders, version, applies_to)`
    Expand source code

        def to_xml(self, folders, version, applies_to):
            if self.query_string:
                self._check_integrity()
                if version.build < EXCHANGE_2010:
                    raise NotImplementedError('QueryString filtering is only supported for Exchange 2010 servers and later')
                elem = create_element('m:QueryString')
                elem.text = self.query_string
                return elem
            # Translate this Q object to a valid Restriction XML tree
            elem = self.xml_elem(folders=folders, version=version, applies_to=applies_to)
            if elem is None:
                return None
            restriction = create_element('m:Restriction')
            restriction.append(elem)
            return restriction

  `def xml_elem(self, folders, version, applies_to)`
    Expand source code

        def xml_elem(self, folders, version, applies_to):
            # Recursively build an XML tree structure of this Q object. If this is an empty leaf (the equivalent of Q()),
            # return None.
            from .indexed_properties import SingleFieldIndexedElement
            # Don't check self.value just yet. We want to return error messages on the field path first, and then the value.
            # This is done in _get_field_path() and _get_clean_value(), respectively.
            self._check_integrity()
            if self.is_empty():
                return None
            if self.is_never():
                raise ValueError("EWS does not support 'never' queries")
            if self.is_leaf():
                elem = self._op_to_xml(self.op)
                field_path = self._get_field_path(folders, applies_to=applies_to, version=version)
                clean_value = self._get_clean_value(field_path=field_path, version=version)
                if issubclass(field_path.field.value_cls, SingleFieldIndexedElement) and not field_path.label:
                    # We allow a filter shortcut of e.g. email_addresses__contains=EmailAddress(label='Foo', ...) instead of
                    # email_addresses__Foo_email_address=.... Set FieldPath label now so we can generate the field_uri.
                    field_path.label = clean_value.label
                elif isinstance(field_path.field, DateTimeBackedDateField):
                    # We need to convert to datetime
                    clean_value = field_path.field.date_to_datetime(clean_value)
                elem.append(field_path.to_xml())
                constant = create_element('t:Constant')
                if self.op != self.EXISTS:
                    # Use .set() to not fill up the create_element() cache with unique values
                    constant.set('Value', value_to_xml_text(clean_value))
                    if self.op in self.CONTAINS_OPS:
                        elem.append(constant)
                    else:
                        uriorconst = create_element('t:FieldURIOrConstant')
                        uriorconst.append(constant)
                        elem.append(uriorconst)
            elif len(self.children) == 1:
                # We have only one child
                elem = self.children[0].xml_elem(folders=folders, version=version, applies_to=applies_to)
            else:
                # We have multiple children. If conn_type is NOT, then group children with AND. We'll add the NOT later
                elem = self._conn_to_xml(self.AND if self.conn_type == self.NOT else self.conn_type)
                # Sort children by field name so we get stable output (for easier testing). Children should never be empty
                for c in sorted(self.children, key=lambda i: i.field_path or ''):
                    elem.append(c.xml_elem(folders=folders, version=version, applies_to=applies_to))
            if elem is None:
                return None  # Should not be necessary, but play safe
            if self.conn_type == self.NOT:
                # Encapsulate everything in the NOT element
                not_elem = self._conn_to_xml(self.conn_type)
                not_elem.append(elem)
                return not_elem
            return elem

`class Restriction (q, folders, applies_to)`

  Implement an EWS Restriction type.

  Expand source code

      class Restriction:
          """Implement an EWS Restriction type."""

          # The type of item the restriction applies to
          FOLDERS = 'folders'
          ITEMS = 'items'
          RESTRICTION_TYPES = (FOLDERS, ITEMS)

          def __init__(self, q, folders, applies_to):
              if not isinstance(q, Q):
                  raise ValueError("'q' value %r must be a Q instance" % q)
              if q.is_empty():
                  raise ValueError("Q object must not be empty")
              from .folders import BaseFolder
              for folder in folders:
                  if not isinstance(folder, BaseFolder):
                      raise ValueError("'folder' value %r must be a Folder instance" % folder)
              if applies_to not in self.RESTRICTION_TYPES:
                  raise ValueError("'applies_to' must be one of %s" % (self.RESTRICTION_TYPES,))
              self.q = q
              self.folders = folders
              self.applies_to = applies_to

          def to_xml(self, version):
              return self.q.to_xml(folders=self.folders, version=version, applies_to=self.applies_to)

          def __str__(self):
              """Print the XML syntax tree."""
              return xml_to_str(self.to_xml(version=self.folders[0].account.version))

  ### Class variables

  `var FOLDERS`
  `var ITEMS`
  `var RESTRICTION_TYPES`

  ### Methods

  `def to_xml(self, version)`
    Expand source code

        def to_xml(self, version):
            return self.q.to_xml(folders=self.folders, version=version, applies_to=self.applies_to)