Python django.db.models.fields.related.ManyToManyField() Examples

def get_all_related_objects(self, local_only=False, include_hidden=False,
                                include_proxy_eq=False):

        include_parents = True if local_only is False else PROXY_PARENTS
        fields = self._get_fields(
            forward=False, reverse=True,
            include_parents=include_parents,
            include_hidden=include_hidden,
        )
        fields = (obj for obj in fields if not isinstance(obj.field, ManyToManyField))
        if include_proxy_eq:
            children = chain.from_iterable(c._relation_tree
                                           for c in self.concrete_model._meta.proxied_children
                                           if c is not self)
            relations = (f.rel for f in children
                         if include_hidden or not f.rel.field.rel.is_hidden())
            fields = chain(fields, relations)
        return list(fields) 

def get_all_related_objects(self, local_only=False, include_hidden=False,
                                include_proxy_eq=False):

        include_parents = True if local_only is False else PROXY_PARENTS
        fields = self._get_fields(
            forward=False, reverse=True,
            include_parents=include_parents,
            include_hidden=include_hidden,
        )
        fields = (obj for obj in fields if not isinstance(obj.field, ManyToManyField))
        if include_proxy_eq:
            children = chain.from_iterable(c._relation_tree
                                           for c in self.concrete_model._meta.proxied_children
                                           if c is not self)
            relations = (f.remote_field for f in children
                         if include_hidden or not f.remote_field.field.remote_field.is_hidden())
            fields = chain(fields, relations)
        return list(fields) 

def reviewable_data_has_changed(obj, new_key_vals, exempt_fields=None):
    """
    Check whether serialized data for the object has changed.

    Args:
        obj (Object): Object representing the persisted state
        new_key_vals (dict_items): List of (key,value) tuples representing the new state
        exempt_fields (list): List of field names where a change does not affect review status

    Returns:
        bool for whether data for any reviewable fields has changed
    """
    changed = False
    exempt_fields = exempt_fields or []
    for key, new_value in [x for x in new_key_vals if x[0] not in exempt_fields]:
        original_value = getattr(obj, key, None)
        if isinstance(new_value, list):
            field_class = obj.__class__._meta.get_field(key).__class__
            original_value_elements = original_value.all()
            if len(new_value) != original_value_elements.count():
                changed = True
            # Just use set compare since none of our fields require duplicates
            elif field_class == ManyToManyField and set(new_value) != set(original_value_elements):
                changed = True
            elif field_class == SortedManyToManyField:
                for new_value_element, original_value_element in zip(new_value, original_value_elements):
                    if new_value_element != original_value_element:
                        changed = True
        elif new_value != original_value:
            changed = True
    return changed 

def serialize_field(self, instance, field_name):
        method_name = 'serialize_{0}'.format(field_name)
        if hasattr(self, method_name):
            return getattr(self, method_name)(instance, field_name)

        try:
            field = self.model._meta.get_field(field_name)
        except FieldDoesNotExist:
            # Abstract field
            pass
        else:
            field_type_method_name = 'serialize_type_{0}'.format(
                field.__class__.__name__.lower())
            if hasattr(self, field_type_method_name):
                return getattr(self, field_type_method_name)(instance, field_name)

            if field.rel:
                # M2M
                if isinstance(field, ManyToManyField):
                    return [self.nested_serialize(r)
                            for r in getattr(instance, field.name).all()]

                rel = getattr(instance, field.name)
                # FK, OtO
                if rel:  # should be a model instance
                    if self.cur_depth >= self.max_depth:
                        return

                    return self.nested_serialize(rel)

        try:
            return getattr(instance, field_name)
        except AttributeError:
            raise AttributeError("The serializer doesn't know how to serialize {0}, "
                                 "please provide it a {1} method."
                                 "".format(field_name, method_name)) 

def deserialize_field(self, source, field_name):
        method_name = 'deserialize_{0}'.format(field_name)
        if hasattr(self, method_name):
            return getattr(self, method_name)(source, field_name)

        field = self.model._meta.get_field(field_name)
        field_type_method_name = 'deserialize_type_{0}'.format(
            field.__class__.__name__.lower())
        if hasattr(self, field_type_method_name):
            return getattr(self, field_type_method_name)(source, field_name)

        val = source.get(field_name)

        # datetime
        typ = field.get_internal_type()
        if val and typ in ('DateField', 'DateTimeField'):
            return datetime.datetime.strptime(val, '%Y-%m-%dT%H:%M:%S.%f')

        if field.rel:
            # M2M
            if isinstance(field, ManyToManyField):
                raise AttributeError

            # FK, OtO
            return self.nested_deserialize(field, source.get(field_name))

        return source.get(field_name) 

def test_get_m2m_field(self):
        field_info = self._details(Person, Person._meta.get_field('m2m_base'))
        self.assertEqual(field_info[1:], (BasePerson, True, True))
        self.assertIsInstance(field_info[0], related.ManyToManyField) 

def test_get_m2m_field(self):
        field_info = self._details(Person, Person._meta.get_field('m2m_base'))
        self.assertEqual(field_info[1:], (BasePerson, True, True))
        self.assertIsInstance(field_info[0], related.ManyToManyField) 

def get_all_related_m2m_objects_with_model(self):
        fields = self._get_fields(forward=False, reverse=True, include_hidden=True)
        return [self._map_model(obj) for obj in fields if isinstance(obj.field, ManyToManyField)] 

def get_all_related_many_to_many_objects(self, local_only=False):
        include_parents = True if local_only is not True else PROXY_PARENTS
        fields = self._get_fields(
            forward=False, reverse=True,
            include_parents=include_parents, include_hidden=True
        )
        return [obj for obj in fields if isinstance(obj.field, ManyToManyField)] 

def model_to_dict(instance, fields=None, exclude=None):
    """
    Returns a dict containing the data in ``instance`` suitable for passing as
    a Form's ``initial`` keyword argument.

    ``fields`` is an optional list of field names. If provided, only the named
    fields will be included in the returned dict.

    ``exclude`` is an optional list of field names. If provided, the named
    fields will be excluded from the returned dict, even if they are listed in
    the ``fields`` argument.
    """
    # avoid a circular import
    from django.db.models.fields.related import ManyToManyField
    opts = instance._meta
    data = {}
    for f in chain(opts.concrete_fields, opts.virtual_fields, opts.many_to_many):
        if not getattr(f, 'editable', False):
            continue
        if fields and f.name not in fields:
            continue
        if exclude and f.name in exclude:
            continue
        if isinstance(f, ManyToManyField):
            # If the object doesn't have a primary key yet, just use an empty
            # list for its m2m fields. Calling f.value_from_object will raise
            # an exception.
            if instance.pk is None:
                data[f.name] = []
            else:
                # MultipleChoiceWidget needs a list of pks, not object instances.
                qs = f.value_from_object(instance)
                if qs._result_cache is not None:
                    data[f.name] = [item.pk for item in qs]
                else:
                    data[f.name] = list(qs.values_list('pk', flat=True))
        else:
            data[f.name] = f.value_from_object(instance)
    return data 

def model_to_dict(instance, fields=None, exclude=None):
    """
    Returns a dict containing the data in ``instance`` suitable for passing as
    a Form's ``initial`` keyword argument.

    ``fields`` is an optional list of field names. If provided, only the named
    fields will be included in the returned dict.

    ``exclude`` is an optional list of field names. If provided, the named
    fields will be excluded from the returned dict, even if they are listed in
    the ``fields`` argument.
    """
    # avoid a circular import
    from django.db.models.fields.related import ManyToManyField
    opts = instance._meta
    data = {}
    for f in opts.fields + opts.many_to_many:
        if not f.editable:
            continue
        if fields and not f.name in fields:
            continue
        if exclude and f.name in exclude:
            continue
        if isinstance(f, ManyToManyField):
            # If the object doesn't have a primary key yet, just use an empty
            # list for its m2m fields. Calling f.value_from_object will raise
            # an exception.
            if instance.pk is None:
                data[f.name] = []
            else:
                # MultipleChoiceWidget needs a list of pks, not object instances.
                data[f.name] = list(f.value_from_object(instance).values_list('pk', flat=True))
        else:
            data[f.name] = f.value_from_object(instance)
    return data 

def post(self, request, *args, **kwargs):
        try:
            msg = _("%(model_name)s '%(instance)s' deleted.") % {
                'model_name': self.verbose_name, 'instance': self.instance
            }
            self.delete_instance()
            messages.success(request, msg)
            return redirect(self.index_url)
        except models.ProtectedError:
            linked_objects = []
            fields = self.model._meta.fields_map.values()
            fields = (obj for obj in fields if not isinstance(
                obj.field, ManyToManyField))
            for rel in fields:
                if rel.on_delete == models.PROTECT:
                    if isinstance(rel, OneToOneRel):
                        try:
                            obj = getattr(self.instance, rel.get_accessor_name())
                        except ObjectDoesNotExist:
                            pass
                        else:
                            linked_objects.append(obj)
                    else:
                        qs = getattr(self.instance, rel.get_accessor_name())
                        for obj in qs.all():
                            linked_objects.append(obj)
            context = self.get_context_data(
                protected_error=True,
                linked_objects=linked_objects
            )
            return self.render_to_response(context) 

def _model_to_dict(instance):
        opts, data = getattr(instance, '_meta'), dict()
        for f in opts.fields + opts.many_to_many:
            if isinstance(f, ManyToManyField):
                if instance.pk is None:
                    data[f.name] = []
                else:
                    data[f.name] = [
                        item.pk for item in f.value_from_object(instance)]
            elif isinstance(f, ForeignKey):
                if getattr(instance, f.name):
                    data[f.name] = getattr(instance, f.name).__str__()
            else:
                data[f.name] = f.value_from_object(instance)
        return data 

def to_dict(instance):
    opts = instance._meta
    data = {}
    for f in opts.concrete_fields + opts.many_to_many:
        if isinstance(f, ManyToManyField):
            if instance.pk is None:
                data[f.name] = []
            else:
                data[f.name] = list(f.value_from_object(instance).values_list('pk', flat=True))
        else:
            data[f.name] = f.value_from_object(instance)
    return data 

def to_dict(self):
        data = {}

        # Iterate over croncrete and many-to-many fields
        for field in self._meta.concrete_fields + self._meta.many_to_many:
            value = None

            # If the value of the field is another model, fetch an instance of it
            # Exception made of tags for which we just retrieve the list of them for later
            # conversion to simple strings
            if isinstance(field, ForeignKey):
                value = self.__getattribute__(field.name)
            elif isinstance(field, ManyToManyField):
                value = list(self.__getattribute__(field.name).all())
            elif isinstance(field, TaggableManager):
                value = list(self.__getattribute__(field.name).all())
            else:
                value = self.__getattribute__(field.name)

            # If the instance of a model as a to_dict() function, call it
            if isinstance(value, TemplateModel):
                data[field.name] = value.to_dict()
            elif isinstance(value, list):
                data[field.name] = []
                for element in value:
                    if isinstance(element, TemplateModel):
                        data[field.name].append(element.to_dict())
                    else:
                        data[field.name].append(str(element))
            else:
                data[field.name] = value

        return data 

def choices(self, cl):
        from django.contrib.admin.views.main import EMPTY_CHANGELIST_VALUE
        yield {
            'selected': self.lookup_val is None and not self.lookup_val_isnull,
            'query_string': cl.get_query_string({},
                [self.lookup_kwarg, self.lookup_kwarg_isnull]),
            'display': _('All'),
        }
        for pk_val, val in self.lookup_choices:
            yield {
                'selected': self.lookup_val == smart_text(pk_val),
                'query_string': cl.get_query_string({
                    self.lookup_kwarg: pk_val,
                }, [self.lookup_kwarg_isnull]),
                'display': val,
            }
        if (isinstance(self.field, ForeignObjectRel) and
                (self.field.field.null or isinstance(self.field.field, ManyToManyField)) or
                hasattr(self.field, 'rel') and (self.field.null or isinstance(self.field, ManyToManyField))):
            yield {
                'selected': bool(self.lookup_val_isnull),
                'query_string': cl.get_query_string({
                    self.lookup_kwarg_isnull: 'True',
                }, [self.lookup_kwarg]),
                'display': EMPTY_CHANGELIST_VALUE,
            } 

def get_all_related_m2m_objects_with_model(self):
        fields = self._get_fields(forward=False, reverse=True, include_hidden=True)
        return [self._map_model(obj) for obj in fields if isinstance(obj.field, ManyToManyField)] 

def get_all_related_many_to_many_objects(self, local_only=False):
        include_parents = True if local_only is not True else PROXY_PARENTS
        fields = self._get_fields(
            forward=False, reverse=True,
            include_parents=include_parents, include_hidden=True
        )
        return [obj for obj in fields if isinstance(obj.field, ManyToManyField)] 

def model_to_dict(instance, fields=None, exclude=None):
    """
    Returns a dict containing the data in ``instance`` suitable for passing as
    a Form's ``initial`` keyword argument.

    ``fields`` is an optional list of field names. If provided, only the named
    fields will be included in the returned dict.

    ``exclude`` is an optional list of field names. If provided, the named
    fields will be excluded from the returned dict, even if they are listed in
    the ``fields`` argument.
    """
    # avoid a circular import
    from django.db.models.fields.related import ManyToManyField
    opts = instance._meta
    data = {}
    for f in chain(opts.concrete_fields, opts.virtual_fields, opts.many_to_many):
        if not getattr(f, 'editable', False):
            continue
        if fields and f.name not in fields:
            continue
        if exclude and f.name in exclude:
            continue
        if isinstance(f, ManyToManyField):
            # If the object doesn't have a primary key yet, just use an empty
            # list for its m2m fields. Calling f.value_from_object will raise
            # an exception.
            if instance.pk is None:
                data[f.name] = []
            else:
                # MultipleChoiceWidget needs a list of pks, not object instances.
                qs = f.value_from_object(instance)
                if qs._result_cache is not None:
                    data[f.name] = [item.pk for item in qs]
                else:
                    data[f.name] = list(qs.values_list('pk', flat=True))
        else:
            data[f.name] = f.value_from_object(instance)
    return data 

def handle_model(self, instance, fields=None, exclude=None):
        """
        Returns a dict containing the data in ``instance`` suitable for passing as
        a Form's ``initial`` keyword argument.

        ``fields`` is an optional list of field names. If provided, only the named
        fields will be included in the returned dict.

        ``exclude`` is an optional list of field names. If provided, the named
        fields will be excluded from the returned dict, even if they are listed in
        the ``fields`` argument.
        """
        # avoid a circular import
        from django.db.models.fields.related import ManyToManyField, ForeignKey

        opts = instance._meta
        data = {}
        # print '='*40
        properties = [k for k, v in instance.__class__.__dict__.items() if type(v) is property]
        for property_name in properties:
            if fields and property_name not in fields:
                continue
            if exclude and property_name in exclude:
                continue
            data[property_name] = self.handle_object(getattr(instance, property_name))
        for f in chain(opts.concrete_fields, opts.private_fields, opts.many_to_many):
            if not getattr(f, "editable", False):
                continue
            if fields and f.name not in fields:
                continue
            if exclude and f.name in exclude:
                continue
            if isinstance(f, ForeignKey):
                # Emulate the naming convention used by django when accessing the
                # related model's id field
                # see https://github.com/django/django/blob/master/django/db/models/fields/__init__.py
                val = getattr(instance, f.attname, None)
                data[f.attname] = val
            elif isinstance(f, ManyToManyField):
                # If the object doesn't have a primary key yet, just use an empty
                # list for its m2m fields. Calling f.value_from_object will raise
                # an exception.
                if instance.pk is None:
                    data[f.name] = []
                else:
                    # MultipleChoiceWidget needs a list of pks, not object instances.
                    qs = f.value_from_object(instance)
                    data[f.name] = [item.pk for item in qs]
            else:
                data[f.name] = self.handle_object(f.value_from_object(instance))
        return data 

def get_model_variables(model):
    variables = []

    for field in model._meta.concrete_fields + model._meta.many_to_many:
        variable = None

        if isinstance(field, ForeignKey):
            variable = "`{}`: {} object".format(
                field.name, get_model_file_link(field.related_model)
            )
        elif isinstance(field, ManyToManyField):
            variable = "`{}`: list of {} objects".format(
                field.name, get_model_file_link(field.related_model)
            )
        elif isinstance(field, TaggableManager):
            variable = "`{}`: list of tags".format(field.name)
        else:
            field_type = None
            if isinstance(field, BooleanField):
                field_type = "boolean"
            elif isinstance(field, CharField):
                field_type = "string"
            elif isinstance(field, TextField):
                field_type = "text"
            elif isinstance(field, DateTimeField):
                field_type = "date"
            elif isinstance(field, InetAddressField):
                field_type = "IP address"
            elif (
                isinstance(field, AutoField)
                or isinstance(field, BigIntegerField)
                or isinstance(field, PositiveIntegerField)
                or isinstance(field, PositiveSmallIntegerField)
            ):
                field_type = "integer".format(field.name)
            else:
                print(
                    "Unknown type for `{}`: {}".format(
                        field.name, field.get_internal_type()
                    )
                )

            if field_type:
                variable = "`{}`: {} value".format(field.name, field_type)

        if variable:
            variables.append(variable)

    return variables