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sqlalchemy.orm strategies Example Code

strategies 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, interfaces, mapper, mapperlib, object_mapper, object_session, query, relationship, session, and sessionmaker 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 / batching.py

# batching.py
import sqlalchemy
from promise import dataloader, promise
from sqlalchemy.orm import Session, strategies
from sqlalchemy.orm.query import QueryContext


def get_batch_resolver(relationship_prop):

    selectin_loader = strategies.SelectInLoader(relationship_prop, (('lazy', 'selectin'),))

    class RelationshipLoader(dataloader.DataLoader):
        cache = False

        def batch_load_fn(self, parents):  # pylint: disable=method-hidden
            child_mapper = relationship_prop.mapper
            parent_mapper = relationship_prop.parent
            session = Session.object_session(parents[0])

            for parent in parents:
                assert session is Session.object_session(parent)
                assert parent not in session.dirty

            states = [(sqlalchemy.inspect(parent), True) for parent in parents]

            query_context = QueryContext(session.query(parent_mapper.entity))

            selectin_loader._load_for_path(
                query_context,
                parent_mapper._path_registry,
                states,
                None,
                child_mapper,
            )


## ... source file continues with no further strategies examples...

Table of Contents

1. Introduction 2. Development Environments 3. Data 4. Web Development 5. Deployment 6. DevOps Changelog What Full Stack Means About the Author Future Directions Page Statuses SQLAlchemy Extensions SQLAlchemy Example Code SQLAlchemy Models sqlalchemy.databases mysql sqlalchemy.dialects mssql sqlalchemy.dialects mysql sqlalchemy.dialects oracle sqlalchemy.schema DDL sqlalchemy.dialects postgresql sqlalchemy.sql.expression Function sqlalchemy.dialects sqlite sqlalchemy.dialects.mysql pymysql sqlalchemy.dialects.postgresql ARRAY sqlalchemy.dialects.postgresql BIGINT sqlalchemy.dialects.postgresql BIT sqlalchemy.dialects.postgresql DOUBLE_PRECISION sqlalchemy.dialects.postgresql ExcludeConstraint sqlalchemy.dialects.postgresql INTEGER sqlalchemy.dialects.postgresql JSON sqlalchemy.dialects.postgresql TSVECTOR sqlalchemy.dialects.postgresql pypostgresql sqlalchemy.dialects.postgresql.base PGCompiler sqlalchemy.dialects.postgresql.base PGIdentifierPreparer sqlalchemy.dialects.postgresql.base PGTypeCompiler sqlalchemy.dialects.postgresql.psycopg2 PGDialect_psycopg2 sqlalchemy.dialects.sqlite pysqlite sqlalchemy.engine Connection sqlalchemy.engine Engine sqlalchemy.engine create_engine sqlalchemy.engine default sqlalchemy.engine url sqlalchemy.engine.default DefaultDialect sqlalchemy.engine.interfaces ExecutionContext sqlalchemy.engine.result ResultMetaData sqlalchemy.engine.result RowProxy sqlalchemy.engine.strategies EngineStrategy sqlalchemy.engine.strategies MockEngineStrategy sqlalchemy.engine.url make_url sqlalchemy.events SchemaEventTarget sqlalchemy.exc ArgumentError sqlalchemy.exc DataError sqlalchemy.exc DatabaseError sqlalchemy.exc IntegrityError sqlalchemy.exc InvalidRequestError sqlalchemy.exc NoInspectionAvailable sqlalchemy.exc NoSuchTableError sqlalchemy.exc OperationalError sqlalchemy.exc ProgrammingError sqlalchemy.exc UnsupportedCompilationError sqlalchemy.ext compiler sqlalchemy.ext.associationproxy AssociationProxy sqlalchemy.ext.automap automap_base sqlalchemy.ext.compiler compiles sqlalchemy.ext.declarative DeclarativeMeta sqlalchemy.ext.declarative declarative_base sqlalchemy.ext.hybrid hybrid_method sqlalchemy.ext.hybrid hybrid_property sqlalchemy.ext.mutable Mutable sqlalchemy.inspection inspect sqlalchemy.orm ColumnProperty sqlalchemy.orm CompositeProperty sqlalchemy.orm Load sqlalchemy.orm Query sqlalchemy.orm RelationshipProperty sqlalchemy.orm SynonymProperty sqlalchemy.orm aliased sqlalchemy.orm attributes sqlalchemy.orm backref sqlalchemy.orm class_mapper sqlalchemy.orm column_property sqlalchemy.orm composite sqlalchemy.orm interfaces sqlalchemy.orm mapper sqlalchemy.orm mapperlib sqlalchemy.orm object_mapper sqlalchemy.orm object_session sqlalchemy.orm relationship sqlalchemy.orm session sqlalchemy.orm sessionmaker sqlalchemy.orm strategies sqlalchemy.orm.attributes InstrumentedAttribute sqlalchemy.orm.attributes QueryableAttribute sqlalchemy.orm.attributes flag_modified sqlalchemy.orm.collections InstrumentedList sqlalchemy.orm.exc NoResultFound sqlalchemy.orm.exc UnmappedClassError sqlalchemy.orm.exc UnmappedInstanceError sqlalchemy.orm.interfaces MapperProperty sqlalchemy.orm.interfaces PropComparator sqlalchemy.orm.mapper Mapper sqlalchemy.orm.properties ColumnProperty sqlalchemy.orm.properties RelationshipProperty sqlalchemy.orm.query Query sqlalchemy.orm.query QueryContext sqlalchemy.orm.relationships RelationshipProperty sqlalchemy.orm.session Session sqlalchemy.orm.session object_session sqlalchemy.orm.util AliasedClass sqlalchemy.orm.util AliasedInsp sqlalchemy.orm.util identity_key sqlalchemy.pool NullPool sqlalchemy.pool StaticPool sqlalchemy.schema CheckConstraint sqlalchemy.schema Column sqlalchemy.schema CreateIndex sqlalchemy.schema CreateTable sqlalchemy.schema DDLElement sqlalchemy.schema ForeignKey sqlalchemy.schema ForeignKeyConstraint sqlalchemy.schema Index sqlalchemy.schema PrimaryKeyConstraint sqlalchemy.schema Table sqlalchemy.sql ClauseElement sqlalchemy.sql column sqlalchemy.sql expression sqlalchemy.sql extract sqlalchemy.sql functions sqlalchemy.sql operators sqlalchemy.sql schema sqlalchemy.sql select sqlalchemy.sql sqltypes sqlalchemy.sql table sqlalchemy.sql.compiler SQLCompiler sqlalchemy.sql.elements ColumnElement sqlalchemy.sql.elements Label sqlalchemy.sql.expression ClauseElement sqlalchemy.sql.expression ColumnClause sqlalchemy.sql.expression ColumnElement sqlalchemy.sql.expression Executable sqlalchemy.sql.expression FunctionElement sqlalchemy.sql.expression UnaryExpression sqlalchemy.sql.functions FunctionElement sqlalchemy.sql.functions GenericFunction sqlalchemy.sql.naming conv sqlalchemy.sql.schema Column sqlalchemy.sql.schema SchemaItem sqlalchemy.sql.sqltypes NullType sqlalchemy.sql.util ClauseAdapter sqlalchemy.sql.visitors traverse sqlalchemy.types Boolean sqlalchemy.types Date sqlalchemy.types DateTime sqlalchemy.types Enum sqlalchemy.types Float sqlalchemy.types Integer sqlalchemy.types Interval sqlalchemy.types NULLTYPE sqlalchemy.types String sqlalchemy.types Text sqlalchemy.types Time sqlalchemy.types TypeEngine sqlalchemy.types UserDefinedType sqlalchemy.types to_instance sqlalchemy.util OrderedDict sqlalchemy.util OrderedSet sqlalchemy.util set_creation_order sqlalchemy.util symbol sqlalchemy.util topological sqlalchemy.util.langhelpers public_factory sqlalchemy.util.langhelpers symbol ...or view the full table of contents.

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