sqlalchemy-orm-interfaces.markdown

title: sqlalchemy.orm interfaces Example Code category: page slug: sqlalchemy-orm-interfaces-examples sortorder: 500031067 toc: False sidebartitle: sqlalchemy.orm interfaces meta: Python example code that shows how to use the interfaces callable from the sqlalchemy.orm module of the SQLAlchemy project.

interfaces is a callable within the sqlalchemy.orm module of the SQLAlchemy project.

ColumnProperty, CompositeProperty, Load, Mapper, Query, RelationshipProperty, Session, SynonymProperty, aliased, attributes, backref, class_mapper, column_property, composite, mapper, mapperlib, object_mapper, object_session, query, relationship, session, sessionmaker, and strategies are several other callables with code examples from the same sqlalchemy.orm package.

Example 1 from graphene-sqlalchemy

graphene-sqlalchemy (project documentation and PyPI package information) is a SQLAlchemy integration for Graphene, which makes it easier to build GraphQL-based APIs into Python web applications. The package allows you to subclass SQLAlchemy classes and build queries around them with custom code to match the backend queries with the GraphQL-based request queries. The project is provided as open source under the MIT license.

graphene-sqlalchemy / graphene_sqlalchemy / converter.py

# converter.py
from enum import EnumMeta

from singledispatch import singledispatch
from sqlalchemy import types
from sqlalchemy.dialects import postgresql
~~from sqlalchemy.orm import interfaces, strategies

from graphene import (ID, Boolean, Dynamic, Enum, Field, Float, Int, List,
                      String)
from graphene.types.json import JSONString

from .batching import get_batch_resolver
from .enums import enum_for_sa_enum
from .fields import (BatchSQLAlchemyConnectionField,
                     default_connection_field_factory)
from .registry import get_global_registry
from .resolvers import get_attr_resolver, get_custom_resolver

try:
    from sqlalchemy_utils import ChoiceType, JSONType, ScalarListType, TSVectorType
except ImportError:
    ChoiceType = JSONType = ScalarListType = TSVectorType = object


is_selectin_available = getattr(strategies, 'SelectInLoader', None)


def get_column_doc(column):
    return getattr(column, "doc", None)


def is_column_nullable(column):
    return bool(getattr(column, "nullable", True))


def convert_sqlalchemy_relationship(relationship_prop, obj_type, connection_field_factory, batching,
                                    orm_field_name, **field_kwargs):
    def dynamic_type():
        direction = relationship_prop.direction
        child_type = obj_type._meta.registry.get_type_for_model(relationship_prop.mapper.entity)
        batching_ = batching if is_selectin_available else False

        if not child_type:
            return None

~~        if direction == interfaces.MANYTOONE or not relationship_prop.uselist:
            return _convert_o2o_or_m2o_relationship(relationship_prop, obj_type, batching_, orm_field_name,
                                                    **field_kwargs)

~~        if direction in (interfaces.ONETOMANY, interfaces.MANYTOMANY):
            return _convert_o2m_or_m2m_relationship(relationship_prop, obj_type, batching_,
                                                    connection_field_factory, **field_kwargs)

    return Dynamic(dynamic_type)


def _convert_o2o_or_m2o_relationship(relationship_prop, obj_type, batching, orm_field_name, **field_kwargs):
    child_type = obj_type._meta.registry.get_type_for_model(relationship_prop.mapper.entity)

    resolver = get_custom_resolver(obj_type, orm_field_name)
    if resolver is None:
        resolver = get_batch_resolver(relationship_prop) if batching else \
            get_attr_resolver(obj_type, relationship_prop.key)

    return Field(child_type, resolver=resolver, **field_kwargs)


def _convert_o2m_or_m2m_relationship(relationship_prop, obj_type, batching, connection_field_factory, **field_kwargs):
    child_type = obj_type._meta.registry.get_type_for_model(relationship_prop.mapper.entity)

    if not child_type._meta.connection:
        return Field(List(child_type), **field_kwargs)

    if connection_field_factory is None:


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