sqlalchemy.orm mapperlib Example Code

mapperlib 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, 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 sqlalchemy-utils

sqlalchemy-utils (project documentation and PyPI package information) is a code library with various helper functions and new data types that make it easier to use SQLAlchemy when building projects that involve more specific storage requirements such as currency. The wide array of data types includes ranged values and aggregated attributes.

sqlalchemy-utils / sqlalchemy_utils / functions / orm.py

# orm.py
from collections import OrderedDict
from functools import partial
from inspect import isclass
from operator import attrgetter

import six
import sqlalchemy as sa
from sqlalchemy.engine.interfaces import Dialect
from sqlalchemy.ext.hybrid import hybrid_property
from sqlalchemy.orm import mapperlib
from sqlalchemy.orm.attributes import InstrumentedAttribute
from sqlalchemy.orm.exc import UnmappedInstanceError
from sqlalchemy.orm.properties import ColumnProperty, RelationshipProperty
from sqlalchemy.orm.query import _ColumnEntity
from sqlalchemy.orm.session import object_session
from sqlalchemy.orm.util import AliasedInsp

from ..utils import is_sequence


def get_class_by_table(base, table, data=None):
    found_classes = set(
        c for c in base._decl_class_registry.values()
        if hasattr(c, '__table__') and c.__table__ is table
    )
    if len(found_classes) > 1:
        if not data:
            raise ValueError(
                "Multiple declarative classes found for table '{0}'. "
                "Please provide data parameter for this function to be able "
                "to determine polymorphic scenarios.".format(
                    table.name
                )
            )


## ... source file abbreviated to get to mapperlib examples ...


        'No column %s is configured on mapper %s...' %
        (column, mapper)
    )


def get_mapper(mixed):
    if isinstance(mixed, sa.orm.query._MapperEntity):
        mixed = mixed.expr
    elif isinstance(mixed, sa.Column):
        mixed = mixed.table
    elif isinstance(mixed, sa.orm.query._ColumnEntity):
        mixed = mixed.expr

    if isinstance(mixed, sa.orm.Mapper):
        return mixed
    if isinstance(mixed, sa.orm.util.AliasedClass):
        return sa.inspect(mixed).mapper
    if isinstance(mixed, sa.sql.selectable.Alias):
        mixed = mixed.element
    if isinstance(mixed, AliasedInsp):
        return mixed.mapper
    if isinstance(mixed, sa.orm.attributes.InstrumentedAttribute):
        mixed = mixed.class_
    if isinstance(mixed, sa.Table):
        mappers = [
            mapper for mapper in mapperlib._mapper_registry
            if mixed in mapper.tables
        ]
        if len(mappers) > 1:
            raise ValueError(
                "Multiple mappers found for table '%s'." % mixed.name
            )
        elif not mappers:
            raise ValueError(
                "Could not get mapper for table '%s'." % mixed.name
            )
        else:
            return mappers[0]
    if not isclass(mixed):
        mixed = type(mixed)
    return sa.inspect(mixed)


def get_bind(obj):
    if hasattr(obj, 'bind'):
        conn = obj.bind
    else:
        try:
            conn = object_session(obj).bind
        except UnmappedInstanceError:


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

Sponsored By

Sentry logo

Software errors are inevitable. Chaos is not. Try Sentry for free.


AssemblyAI logo

The most accurate speech-to-text API. Built for Python developers.

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 ExtensionsSQLAlchemy Example CodeSQLAlchemy Modelssqlalchemy.databases mysqlsqlalchemy.dialects mssqlsqlalchemy.dialects mysqlsqlalchemy.dialects oraclesqlalchemy.schema DDLsqlalchemy.dialects postgresqlsqlalchemy.sql.expression Functionsqlalchemy.dialects sqlitesqlalchemy.dialects.mysql pymysqlsqlalchemy.dialects.postgresql ARRAYsqlalchemy.dialects.postgresql BIGINTsqlalchemy.dialects.postgresql BITsqlalchemy.dialects.postgresql DOUBLE_PRECISIONsqlalchemy.dialects.postgresql ExcludeConstraintsqlalchemy.dialects.postgresql INTEGERsqlalchemy.dialects.postgresql JSONsqlalchemy.dialects.postgresql TSVECTORsqlalchemy.dialects.postgresql pypostgresqlsqlalchemy.dialects.postgresql.base PGCompilersqlalchemy.dialects.postgresql.base PGIdentifierPreparersqlalchemy.dialects.postgresql.base PGTypeCompilersqlalchemy.dialects.postgresql.psycopg2 PGDialect_psycopg2sqlalchemy.dialects.sqlite pysqlitesqlalchemy.engine Connectionsqlalchemy.engine Enginesqlalchemy.engine create_enginesqlalchemy.engine defaultsqlalchemy.engine urlsqlalchemy.engine.default DefaultDialectsqlalchemy.engine.interfaces ExecutionContextsqlalchemy.engine.result ResultMetaDatasqlalchemy.engine.result RowProxysqlalchemy.engine.strategies EngineStrategysqlalchemy.engine.strategies MockEngineStrategysqlalchemy.engine.url make_urlsqlalchemy.events SchemaEventTargetsqlalchemy.exc ArgumentErrorsqlalchemy.exc DataErrorsqlalchemy.exc DatabaseErrorsqlalchemy.exc IntegrityErrorsqlalchemy.exc InvalidRequestErrorsqlalchemy.exc NoInspectionAvailablesqlalchemy.exc NoSuchTableErrorsqlalchemy.exc OperationalErrorsqlalchemy.exc ProgrammingErrorsqlalchemy.exc UnsupportedCompilationErrorsqlalchemy.ext compilersqlalchemy.ext.associationproxy AssociationProxysqlalchemy.ext.automap automap_basesqlalchemy.ext.compiler compilessqlalchemy.ext.declarative DeclarativeMetasqlalchemy.ext.declarative declarative_basesqlalchemy.ext.hybrid hybrid_methodsqlalchemy.ext.hybrid hybrid_propertysqlalchemy.ext.mutable Mutablesqlalchemy.inspection inspectsqlalchemy.orm ColumnPropertysqlalchemy.orm CompositePropertysqlalchemy.orm Loadsqlalchemy.orm Querysqlalchemy.orm RelationshipPropertysqlalchemy.orm SynonymPropertysqlalchemy.orm aliasedsqlalchemy.orm attributessqlalchemy.orm backrefsqlalchemy.orm class_mappersqlalchemy.orm column_propertysqlalchemy.orm compositesqlalchemy.orm interfacessqlalchemy.orm mappersqlalchemy.orm mapperlibsqlalchemy.orm object_mappersqlalchemy.orm object_sessionsqlalchemy.orm relationshipsqlalchemy.orm sessionsqlalchemy.orm sessionmakersqlalchemy.orm strategiessqlalchemy.orm.attributes InstrumentedAttributesqlalchemy.orm.attributes QueryableAttributesqlalchemy.orm.attributes flag_modifiedsqlalchemy.orm.collections InstrumentedListsqlalchemy.orm.exc NoResultFoundsqlalchemy.orm.exc UnmappedClassErrorsqlalchemy.orm.exc UnmappedInstanceErrorsqlalchemy.orm.interfaces MapperPropertysqlalchemy.orm.interfaces PropComparatorsqlalchemy.orm.mapper Mappersqlalchemy.orm.properties ColumnPropertysqlalchemy.orm.properties RelationshipPropertysqlalchemy.orm.query Querysqlalchemy.orm.query QueryContextsqlalchemy.orm.relationships RelationshipPropertysqlalchemy.orm.session Sessionsqlalchemy.orm.session object_sessionsqlalchemy.orm.util AliasedClasssqlalchemy.orm.util AliasedInspsqlalchemy.orm.util identity_keysqlalchemy.pool NullPoolsqlalchemy.pool StaticPoolsqlalchemy.schema CheckConstraintsqlalchemy.schema Columnsqlalchemy.schema CreateIndexsqlalchemy.schema CreateTablesqlalchemy.schema DDLElementsqlalchemy.schema ForeignKeysqlalchemy.schema ForeignKeyConstraintsqlalchemy.schema Indexsqlalchemy.schema PrimaryKeyConstraintsqlalchemy.schema Tablesqlalchemy.sql ClauseElementsqlalchemy.sql columnsqlalchemy.sql expressionsqlalchemy.sql extractsqlalchemy.sql functionssqlalchemy.sql operatorssqlalchemy.sql schemasqlalchemy.sql selectsqlalchemy.sql sqltypessqlalchemy.sql tablesqlalchemy.sql.compiler SQLCompilersqlalchemy.sql.elements ColumnElementsqlalchemy.sql.elements Labelsqlalchemy.sql.expression ClauseElementsqlalchemy.sql.expression ColumnClausesqlalchemy.sql.expression ColumnElementsqlalchemy.sql.expression Executablesqlalchemy.sql.expression FunctionElementsqlalchemy.sql.expression UnaryExpressionsqlalchemy.sql.functions FunctionElementsqlalchemy.sql.functions GenericFunctionsqlalchemy.sql.naming convsqlalchemy.sql.schema Columnsqlalchemy.sql.schema SchemaItemsqlalchemy.sql.sqltypes NullTypesqlalchemy.sql.util ClauseAdaptersqlalchemy.sql.visitors traversesqlalchemy.types Booleansqlalchemy.types Datesqlalchemy.types DateTimesqlalchemy.types Enumsqlalchemy.types Floatsqlalchemy.types Integersqlalchemy.types Intervalsqlalchemy.types NULLTYPEsqlalchemy.types Stringsqlalchemy.types Textsqlalchemy.types Timesqlalchemy.types TypeEnginesqlalchemy.types UserDefinedTypesqlalchemy.types to_instancesqlalchemy.util OrderedDictsqlalchemy.util OrderedSetsqlalchemy.util set_creation_ordersqlalchemy.util symbolsqlalchemy.util topologicalsqlalchemy.util.langhelpers public_factorysqlalchemy.util.langhelpers symbol ...or view the full table of contents.

Full Stack Python

Full Stack Python is an open book that explains concepts in plain language and provides helpful resources for those topics.
Updates via Twitter & Facebook.

Matt Makai 2012-2020