sqlalchemy.ext.compiler compiles Example Code

compiles is a callable within the sqlalchemy.ext.compiler 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)


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


    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)
def _render_textual_index_column(element, compiler, **kw):
    return compiler.process(element.text, **kw)


class _literal_bindparam(_BindParamClause):
    pass


@compiles(_literal_bindparam)
def _render_literal_bindparam(element, compiler, **kw):
    return compiler.render_literal_bindparam(element, **kw)


def _get_index_expressions(idx):
    return list(idx.expressions)


def _get_index_column_names(idx):
    return [getattr(exp, "name", None) for exp in _get_index_expressions(idx)]


def _column_kwargs(col):
    if sqla_13:
        return col.kwargs
    else:
        return {}


def _get_constraint_final_name(constraint, dialect):
    if constraint.name is None:
        return None
    elif sqla_14:
        return dialect.identifier_preparer.format_constraint(


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

Example 2 from GeoAlchemy2

GeoAlchemy2 (project documentation and PyPI package information) extends SQLAlchemy with new data types for working with geospatial databases, particularly PostGIS, which is a spatial database extender for PostgreSQL. The project is provided as open source under the MIT license.

GeoAlchemy2 / geoalchemy2 / functions.py

# functions.py
import re

from sqlalchemy import inspect
from sqlalchemy.sql import functions
from sqlalchemy.sql.elements import ColumnElement
from sqlalchemy.ext.compiler import compiles

from . import types
from . import elements


class TableRowElement(ColumnElement):
    def __init__(self, selectable):
        self.selectable = selectable

    @property
    def _from_objects(self):
        return [self.selectable]


class ST_AsGeoJSON(functions.GenericFunction):

    name = "ST_AsGeoJSON"

    def __init__(self, *args, **kwargs):
        expr = kwargs.pop('expr', None)
        args = list(args)
        if expr is not None:
            args = [expr] + args
        for idx, element in enumerate(args):


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


        attributes['type'] = type_

        type_str = '{0}.{1}'.format(type_.__module__, type_.__name__)
        docs.append('Return type: :class:`{0}`.'.format(type_str))

    if len(docs) != 0:
        attributes['__doc__'] = '\n\n'.join(docs)

    globals()[name] = type(name, (GenericFunction,), attributes)




_SQLITE_FUNCTIONS = {
    "ST_GeomFromEWKT": "GeomFromEWKT",
    "ST_GeomFromEWKB": "GeomFromEWKB",
    "ST_AsBinary": "AsBinary",
    "ST_AsEWKB": "AsEWKB",
    "ST_AsGeoJSON": "AsGeoJSON",
}


def _compiles_default(cls):
    def _compile_default(element, compiler, **kw):
        return "{}({})".format(cls, compiler.process(element.clauses, **kw))
    compiles(globals()[cls])(_compile_default)


def _compiles_sqlite(cls, fn):
    def _compile_sqlite(element, compiler, **kw):
        return "{}({})".format(fn, compiler.process(element.clauses, **kw))
    compiles(globals()[cls], "sqlite")(_compile_sqlite)


for cls, fn in _SQLITE_FUNCTIONS.items():
    _compiles_default(cls)
    _compiles_sqlite(cls, fn)

                if element.extended:
                    func_name = element.geom_from_extended_version
                    func_args = [element.data]
                else:
                    func_name = element.geom_from
                    func_args = [element.data, element.srid]
                args[idx] = getattr(functions.func, func_name)(*func_args)
            else:
                try:
                    insp = inspect(element)
                    if hasattr(insp, "selectable"):
                        args[idx] = TableRowElement(insp.selectable)
                except Exception:
                    continue

        functions.GenericFunction.__init__(self, *args, **kwargs)

    __doc__ = (
        'Return the geometry as a GeoJSON "geometry" object, or the row as a '
        'GeoJSON feature" object (PostGIS 3 only). (Cf GeoJSON specifications RFC '
        '7946). 2D and 3D Geometries are both supported. GeoJSON only support SFS '
        '1.1 geometry types (no curve support for example). '
        'See https://postgis.net/docs/ST_AsGeoJSON.html')


@compiles(TableRowElement)
def _compile_table_row_thing(element, compiler, **kw):

    compiled = compiler.process(list(element.selectable.columns)[0], **kw)

    schema = getattr(element.selectable, "schema", "")
    name = element.selectable.name
    pattern = r"(.?%s.?\.)?(.?%s.?)\." % (schema, name)
    m = re.match(pattern, compiled)
    if m:
        return m.group(2)

    return compiled.split(".")[0]


class GenericFunction(functions.GenericFunction):

    _register = False

    def __init__(self, *args, **kwargs):
        expr = kwargs.pop('expr', None)
        args = list(args)
        if expr is not None:
            args = [expr] + args
        for idx, elem in enumerate(args):


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

Example 3 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 / expressions.py

# expressions.py
import sqlalchemy as sa
from sqlalchemy.dialects import postgresql
from sqlalchemy.ext.compiler import compiles
from sqlalchemy.sql.expression import ColumnElement, FunctionElement
from sqlalchemy.sql.functions import GenericFunction

from .functions.orm import quote


class array_get(FunctionElement):
    name = 'array_get'


@compiles(array_get)
def compile_array_get(element, compiler, **kw):
    args = list(element.clauses)
    if len(args) != 2:
        raise Exception(
            "Function 'array_get' expects two arguments (%d given)." %
            len(args)
        )

    if not hasattr(args[1], 'value') or not isinstance(args[1].value, int):
        raise Exception(
            "Second argument should be an integer."
        )
    return '(%s)[%s]' % (
        compiler.process(args[0]),
        sa.text(str(args[1].value + 1))
    )


class row_to_json(GenericFunction):
    name = 'row_to_json'
    type = postgresql.JSON


@compiles(row_to_json, 'postgresql')
def compile_row_to_json(element, compiler, **kw):
    return "%s(%s)" % (element.name, compiler.process(element.clauses))


class json_array_length(GenericFunction):
    name = 'json_array_length'
    type = sa.Integer


@compiles(json_array_length, 'postgresql')
def compile_json_array_length(element, compiler, **kw):
    return "%s(%s)" % (element.name, compiler.process(element.clauses))


class Asterisk(ColumnElement):
    def __init__(self, selectable):
        self.selectable = selectable


@compiles(Asterisk)
def compile_asterisk(element, compiler, **kw):
    return '%s.*' % quote(compiler.dialect, element.selectable.name)



## ... source file continues with no further compiles 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