Graphene-SQLAlchemy-Filter

Filters for Graphene SQLAlchemy integration

Quick start

Create a filter and add it to the graphene field.

from graphene_sqlalchemy_filter import FilterableConnectionField, FilterSet


class UserFilter(FilterSet):
    is_admin = graphene.Boolean()

    class Meta:
        model = User
        fields = {
            'username': ['eq', 'ne', 'in', 'ilike'],
            'is_active': [...],  # shortcut!
        }

    @staticmethod
    def is_admin_filter(info, query, value):
        if value:
            return User.username == 'admin'
        else:
            return User.username != 'admin'


class Query(ObjectType):
    all_users = FilterableConnectionField(UserConnection, filters=UserFilter())

Now, we're going to create query.

{
  allUsers (
    filters: {
      isActive: true,
      or: [
        {isAdmin: true},
        {usernameIn: ["moderator", "cool guy"]}
      ]
    }
  ){
    edges {
      node {
        id
        username
      }
    }
  }
}

---

Filters

FilterSet class must inherit graphene_sqlalchemy_filter.FilterSet or your subclass of this class.

There are three types of filters:

1. automatically generated filters
2. simple filters
3. filters that require join

Automatically generated filters

class UserFilter(FilterSet):
   class Meta:
       model = User
       fields = {
           'username': ['eq', 'ne', 'in', 'ilike'],
           'is_active': [...],  # shortcut!
       }

Metaclass must contain the sqlalchemy model and fields.

Automatically generated filters must be specified by fields variable. Key - field name of sqlalchemy model, value - list of expressions (or shortcut).

Shortcut (default: [...]) will add all the allowed filters for this type of sqlalchemy field (does not work with hybrid property).

Key	Description	GraphQL postfix
eq	equal
ne	not equal	Ne
like	like	Like
ilike	insensitive like	Ilike
is_null	is null	IsNull
in	in	In
not_in	not in	NotIn
lt	less than	Lt
lte	less than or equal	Lte
gt	greater than	Gt
gte	greater than or equal	Gte
range	in range	Range
contains	contains (PostgreSQL array)	Contains
contained_by	contained_by (PostgreSQL array)	ContainedBy
overlap	overlap (PostgreSQL array)	Overlap

Simple filters

class UserFilter(FilterSet):
    is_admin = graphene.Boolean()

    @staticmethod
    def is_admin_filter(info, query, value):
        if value:
            return User.username == 'admin'
        else:
            return User.username != 'admin'

Each simple filter has a class variable that passes to GraphQL schema as an input type and function <field_name>_filter that makes filtration.

The filtration function takes the following arguments:

• info - ResolveInfo graphene object
• query - sqlalchemy query (not used in that filters type)
• value - the value of a filter

The return value can be any type of sqlalchemy clause. This means that you can return not_(and_(or_(...), ...)).

Metaclass is not required if you do not need automatically generated filters.

Filters that require join

This type of filter is the same as simple filters but has a different return type.

The filtration function should return a new sqlalchemy query and clause (like simple filters).

class UserFilter(FilterSet):
    is_moderator = graphene.Boolean()

    @classmethod
    def is_moderator_filter(cls, info, query, value):
        membership = cls.aliased(query, Membership, name='is_moderator')
  
        query = query.outerjoin(
            membership,
            and_(
                User.id == membership.user_id,
                membership.is_moderator.is_(True),
            ),
        )

        if value:
            filter_ = membership.id.isnot(None)
        else:
            filter_ = membership.id.is_(None)

        return query, filter_

Model aliases

The function cls.aliased(query, model, name='...') returns sqlalchemy alias from the query. It has one differing parameter - query (SQLAlchemy Query object). Other arguments are the same as sqlalchemy.orm.aliased.

Identical joins will be skipped by sqlalchemy.

Changed in version 1.7: The first parameter is now a query.

Features

Filter registration and nested fields filters

Filters can be registered for each SQLAlchemy model in a subclass of FilterableConnectionField.

Register your filters by inheriting FilterableConnectionField and setting filters (key - SQLAlchemy model, value - FilterSet object).

class CustomField(FilterableConnectionField):
    filters = {
        User: UserFilter(),
    }

Overriding SQLAlchemyObjectType.connection_field_factory allows you to generate nested connections with filters.

class UserNode(SQLAlchemyObjectType):
    class Meta:
        model = User
        interfaces = (Node,)
        connection_field_factory = CustomField.factory

Important:

1. pagination (first/after, last/before) are performed by python (keep this in mind when working with large amounts of data)
2. nested filters work by dataloaders
3. this module optimizes one-to-many relationships, to optimize many-to-one relationships use sqlalchemy_bulk_lazy_loader
4. nested filters require graphene_sqlalchemy>=2.1.2

Example

# Filters

class UserFilter(FilterSet):
   class Meta:
       model = User
       fields = {'is_active': [...]}
       


class CustomField(FilterableConnectionField):
    filters = {
        User: UserFilter(),
    }


# Nodes

class UserNode(SQLAlchemyObjectType):
    class Meta:
        model = User
        interfaces = (Node,)
        connection_field_factory = CustomField.factory


class GroupNode(SQLAlchemyObjectType):
    class Meta:
        model = Group
        interfaces = (Node,)
        connection_field_factory = CustomField.factory


# Connections

class UserConnection(Connection):
    class Meta:
        node = UserNode


class GroupConnection(Connection):
    class Meta:
        node = GroupNode


# Query

class Query(ObjectType):
    all_users = CustomField(UserConnection)
    all_groups = CustomField(GroupConnection)

{
  allUsers (filters: {isActive: true}){
    edges { node { id } }
  }
  allGroups {
    edges {
      node {
        users (filters: {isActive: true}) {
          edges { node { id } }
        }
      }
    }
  }
}

Rename GraphQL filter field

class CustomField(FilterableConnectionField):
    filter_arg = 'where'


class Query(ObjectType):
    all_users = CustomField(UserConnection, where=UserFilter())
    all_groups = FilterableConnectionField(GroupConnection, filters=GroupFilter())

{
  allUsers (where: {isActive: true}){
    edges { node { id } }
  }
  allGroups (filters: {nameIn: ["python", "development"]}){
    edges { node { id } }
  }
}

Rename expression

class BaseFilter(FilterSet):
    GRAPHQL_EXPRESSION_NAMES = dict(
        FilterSet.GRAPHQL_EXPRESSION_NAMES,
        **{'eq': 'equal', 'not': 'i_never_asked_for_this'}
    )

    class Meta:
        abstract = True


class UserFilter(BaseFilter):
    class Meta:
        model = User
        fields = {'first_name': ['eq'], 'last_name': ['eq']}

{
  allUsers (filters: {iNeverAskedForThis: {firstNameEqual: "Adam", lastNameEqual: "Jensen"}}){
    edges { node { id } }
  }
}

Custom shortcut value

class BaseFilter(FilterSet):
    ALL = '__all__'

    class Meta:
        abstract = True


class UserFilter(BaseFilter):
    class Meta:
        model = User
        fields = {'username': '__all__'}

Localization of documentation

class BaseFilter(FilterSet):
    DESCRIPTIONS = {
        'eq': 'Полностью совпадает.',
        'ne': 'Не совпадает.',
        'like': 'Регистрозависимая проверка строки по шлабону.',
        'ilike': 'Регистронезависимая проверка строки по шлабону.',
        'regexp': 'Регистрозависимая проверка строки по регулярному выражению.',
        'is_null': 'Равно ли значение `null`. Принемает `true` или `false`.',
        'in': 'Проверка вхождения в список.',
        'not_in': 'Проверка не вхождения в список.',
        'lt': 'Меньше, чем указанное значение.',
        'lte': 'Меньше или равно указанному значению.',
        'gt': 'Больше, чем указанное значение.',
        'gte': 'Больше или равно указанному значению.',
        'range': 'Значение входит в диапазон значений.',
        'and': 'Объединение фильтров с помощью ``AND``.',
        'or': 'Объединение фильтров с помощью ``OR``.',
        'not': 'Отрицание указанных фильтров.',
    }

    class Meta:
        abstract = True

Custom expression

def today_filter(field, value: bool):
    today = func.date(field) == date.today()
    return today if value else not_(today)


class BaseFilter(FilterSet):
    # Add expression.
    TODAY = 'today'

    EXTRA_EXPRESSIONS = {
        'today': {
            # Add the name of the expression in GraphQL.
            'graphql_name': 'today',
            # Update allowed filters (used by shortcut).
            'for_types': [types.Date, types.DateTime],
            # Add a filtering function (takes the sqlalchemy field and value).
            'filter': today_filter,
            # Add the GraphQL input type. Column type by default.
            'input_type': (
                lambda type_, nullable, doc: graphene.Boolean(nullable=False)
            ),
            # Description for the GraphQL schema.
            'description': 'It is today.',
        }
    }

    class Meta:
        abstract = True


class PostFilter(BaseFilter):
    class Meta:
        model = Post
        fields = {'created': ['today'], 'updated': [...]}

{
  allPosts (filters: {createdToday: false, updatedToday: true}){
    edges { node { id } }
  }
}

Custom column types

ALLOWED_FILTERS and EXTRA_ALLOWED_FILTERS only affect shortcut.

If you do not use the shortcut, you can skip the next steps described in the section.

class MyString(types.String):
    pass


class BaseFilter(FilterSet):
    # You can override all allowed filters
    # ALLOWED_FILTERS = {types.Integer: ['eq']}
    
    # Or add new column type
    EXTRA_ALLOWED_FILTERS = {MyString: ['eq']}

    class Meta:
        abstract = True