sqlalchemy.schema Column Example Code

Column is a class within the sqlalchemy.schema module of the SQLAlchemy project.

Example 1 from alembic

Alembic (project documentation and PyPI page) is a data migrations tool used with SQLAlchemy to make database schema changes. The Alembic project is open sourced under the MIT license.

alembic / alembic / util / sqla_compat.py

# sqla_compat.py
import re

from sqlalchemy import __version__
from sqlalchemy import inspect
from sqlalchemy import schema
from sqlalchemy import sql
from sqlalchemy import types as sqltypes
from sqlalchemy.ext.compiler import compiles
from sqlalchemy.schema import CheckConstraint
from sqlalchemy.schema import Column
from sqlalchemy.schema import ForeignKeyConstraint
from sqlalchemy.sql.elements import quoted_name
from sqlalchemy.sql.expression import _BindParamClause
from sqlalchemy.sql.expression import _TextClause as TextClause
from sqlalchemy.sql.visitors import traverse

from . import compat


def _safe_int(value):
    try:
        return int(value)
    except:
        return value


_vers = tuple(
    [_safe_int(x) for x in re.findall(r"(\d+|[abc]\d)", __version__)]
)
sqla_110 = _vers >= (1, 1, 0)
sqla_1115 = _vers >= (1, 1, 15)
sqla_120 = _vers >= (1, 2, 0)
sqla_1216 = _vers >= (1, 2, 16)
sqla_13 = _vers >= (1, 3)


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


    tokens = spec.split(".")
    tokens.pop(-1)  # colname
    tablekey = ".".join(tokens)
    return tablekey == constraint.parent.key


def _is_type_bound(constraint):
    return constraint._type_bound


def _find_columns(clause):

    cols = set()
    traverse(clause, {}, {"column": cols.add})
    return cols


def _remove_column_from_collection(collection, column):

    to_remove = collection[column.key]
    collection.remove(to_remove)


def _textual_index_column(table, text_):
    if isinstance(text_, compat.string_types):
        c = Column(text_, sqltypes.NULLTYPE)
        table.append_column(c)
        return c
    elif isinstance(text_, TextClause):
        return _textual_index_element(table, text_)
    else:
        raise ValueError("String or text() construct expected")


class _textual_index_element(sql.ColumnElement):

    __visit_name__ = "_textual_idx_element"

    def __init__(self, table, text):
        self.table = table
        self.text = text
        self.key = text.text
        self.fake_column = schema.Column(self.text.text, sqltypes.NULLTYPE)
        table.append_column(self.fake_column)

    def get_children(self):
        return [self.fake_column]


@compiles(_textual_index_element)


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

Example 2 from GINO

GINO (project documentation and PyPI package information) is an object-relational mapper (ORM) built on SQLAlchemy that is non-blocking and therefore designed to work properly with asynchronously-run code, for example, an application written with asyncio.

GINO is open sourced under the BSD License.

GINO / src/gino / loader.py

# loader.py
import types
import warnings

from sqlalchemy import select
from sqlalchemy.schema import Column
from sqlalchemy.sql.elements import Label

from .declarative import Model


class Loader:

    @classmethod
    def get(cls, value):
        from .crud import Alias

        if isinstance(value, Loader):
            rv = value
        elif isinstance(value, type) and issubclass(value, Model):
            rv = ModelLoader(value)
        elif isinstance(value, Alias):
            rv = AliasLoader(value)
        elif isinstance(value, Column):
            rv = ColumnLoader(value)
        elif isinstance(value, Label):
            rv = ColumnLoader(value.name)
        elif isinstance(value, tuple):
            rv = TupleLoader(value)
        elif callable(value):
            rv = CallableLoader(value)
        else:
            rv = ValueLoader(value)
        return rv

    @property
    def query(self):
        rv = select(self.get_columns())
        from_clause = self.get_from()
        if from_clause is not None:
            rv = rv.select_from(from_clause)
        return rv.execution_options(loader=self)

    def do_load(self, row, context):
        raise NotImplementedError

    def get_columns(self):
        return []

    def get_from(self):
        return None

    def __getattr__(self, item):
        return getattr(self.query, item)


_none = object()


def _get_column(model, column_or_name) -> Column:
    if isinstance(column_or_name, str):
        return getattr(model, column_or_name)

    if isinstance(column_or_name, Column):
        if column_or_name in model:
            return column_or_name
        raise AttributeError(
            "Column {} does not belong to model {}".format(column_or_name, model)
        )

    raise TypeError(
        "Unknown column {} with type {}".format(column_or_name, type(column_or_name))
    )


class ModelLoader(Loader):

    def __init__(self, model, *columns, **extras):
        self.model = model
        self._distinct = None
        if columns:
            self.columns = [_get_column(model, name) for name in columns]
        else:
            self.columns = model
        self.extras = dict((key, self.get(value)) for key, value in extras.items())
        self.on_clause = None

    def _do_load(self, row):


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

Sponsored By

Sentry logo

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

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.dialects mssqlsqlalchemy.dialects mysqlsqlalchemy.dialects oraclesqlalchemy.dialects postgresqlsqlalchemy.schema DDLsqlalchemy.dialects sqlitesqlalchemy.sql.expression Functionsqlalchemy.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 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 IntegrityErrorsqlalchemy.exc InvalidRequestErrorsqlalchemy.exc NoInspectionAvailablesqlalchemy.exc OperationalErrorsqlalchemy.exc ProgrammingErrorsqlalchemy.ext compilersqlalchemy.ext.automap automap_basesqlalchemy.ext.compiler compilessqlalchemy.ext.declarative DeclarativeMetasqlalchemy.ext.declarative declarative_basesqlalchemy.ext.hybrid hybrid_propertysqlalchemy.ext.mutable Mutablesqlalchemy.inspection inspectsqlalchemy.orm ColumnPropertysqlalchemy.orm CompositePropertysqlalchemy.orm SynonymPropertysqlalchemy.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.collections InstrumentedListsqlalchemy.orm.exc NoResultFoundsqlalchemy.orm.exc UnmappedClassErrorsqlalchemy.orm.exc UnmappedInstanceErrorsqlalchemy.orm.interfaces MapperPropertysqlalchemy.orm.interfaces PropComparatorsqlalchemy.orm.properties ColumnPropertysqlalchemy.orm.properties RelationshipPropertysqlalchemy.orm.query Querysqlalchemy.orm.query QueryContextsqlalchemy.orm.session Sessionsqlalchemy.orm.session object_sessionsqlalchemy.orm.util AliasedInspsqlalchemy.pool NullPoolsqlalchemy.pool StaticPoolsqlalchemy.schema CheckConstraintsqlalchemy.schema Columnsqlalchemy.schema CreateIndexsqlalchemy.schema DDLElementsqlalchemy.schema ForeignKeysqlalchemy.schema ForeignKeyConstraintsqlalchemy.schema PrimaryKeyConstraintsqlalchemy.schema Tablesqlalchemy.sql ClauseElementsqlalchemy.sql columnsqlalchemy.sql expressionsqlalchemy.sql functionssqlalchemy.sql operatorssqlalchemy.sql schemasqlalchemy.sql selectsqlalchemy.sql sqltypessqlalchemy.sql tablesqlalchemy.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 Enumsqlalchemy.types Integersqlalchemy.types NULLTYPEsqlalchemy.types Stringsqlalchemy.types TypeEnginesqlalchemy.types UserDefinedTypesqlalchemy.types to_instancesqlalchemy.util OrderedDictsqlalchemy.util OrderedSetsqlalchemy.util set_creation_ordersqlalchemy.util topologicalsqlalchemy.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