sqlalchemy.schema ForeignKey Example Code

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

CheckConstraint, Column, CreateIndex, CreateTable, DDLElement, ForeignKeyConstraint, Index, PrimaryKeyConstraint, and Table are several other callables with code examples from the same sqlalchemy.schema package.

Example 1 from sqlacodegen

sqlacodegen (PyPI package information) is a tool for reading from an existing relational database to generate code to create SQLAlchemy models based on that database. The project is primarily written and maintained by Alex Grönholm (agronholm) and it is open sourced under the MIT license.

sqlacodegen / sqlacodegen / codegen.py

# codegen.py
from __future__ import unicode_literals, division, print_function, absolute_import

import inspect
import re
import sys
from collections import defaultdict
from importlib import import_module
from inspect import ArgSpec
from keyword import iskeyword

import sqlalchemy
import sqlalchemy.exc
from sqlalchemy import (
    Enum, ForeignKeyConstraint, PrimaryKeyConstraint, CheckConstraint, UniqueConstraint, Table,
    Column, Float)
from sqlalchemy.schema import ForeignKey
from sqlalchemy.sql.sqltypes import NullType
from sqlalchemy.types import Boolean, String
from sqlalchemy.util import OrderedDict

try:
    from sqlalchemy import ARRAY
except ImportError:
    from sqlalchemy.dialects.postgresql import ARRAY

try:
    from sqlalchemy import Computed
except ImportError:
    Computed = None

try:
    import geoalchemy2  # noqa: F401
except ImportError:
    pass

_re_boolean_check_constraint = re.compile(r"(?:(?:.*?)\.)?(.*?) IN \(0, 1\)")
_re_column_name = re.compile(r'(?:(["`]?)(?:.*)\1\.)?(["`]?)(.*)\2')
_re_enum_check_constraint = re.compile(r"(?:(?:.*?)\.)?(.*?) IN \((.+)\)")
_re_enum_item = re.compile(r"'(.*?)(?<!\\)'")
_re_invalid_identifier = re.compile(r'[^a-zA-Z0-9_]' if sys.version_info[0] < 3 else r'(?u)\W')


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


                value = getattr(coltype, attr, missing)
                default = defaults.get(attr, missing)
                if value is missing or value == default:
                    use_kwargs = True
                elif use_kwargs:
                    args.append('{0}={1}'.format(attr, repr(value)))
                else:
                    args.append(repr(value))

        rendered = coltype.__class__.__name__
        if args:
            rendered += '({0})'.format(', '.join(args))

        return rendered

    def render_constraint(self, constraint):
        def render_fk_options(*opts):
            opts = [repr(opt) for opt in opts]
            for attr in 'ondelete', 'onupdate', 'deferrable', 'initially', 'match':
                value = getattr(constraint, attr, None)
                if value:
                    opts.append('{0}={1!r}'.format(attr, value))

            return ', '.join(opts)

        if isinstance(constraint, ForeignKey):
            remote_column = '{0}.{1}'.format(constraint.column.table.fullname,
                                             constraint.column.name)
            return 'ForeignKey({0})'.format(render_fk_options(remote_column))
        elif isinstance(constraint, ForeignKeyConstraint):
            local_columns = _get_column_names(constraint)
            remote_columns = ['{0}.{1}'.format(fk.column.table.fullname, fk.column.name)
                              for fk in constraint.elements]
            return 'ForeignKeyConstraint({0})'.format(
                render_fk_options(local_columns, remote_columns))
        elif isinstance(constraint, CheckConstraint):
            return 'CheckConstraint({0!r})'.format(
                self._get_compiled_expression(constraint.sqltext))
        elif isinstance(constraint, UniqueConstraint):
            columns = [repr(col.name) for col in constraint.columns]
            return 'UniqueConstraint({0})'.format(', '.join(columns))

    @staticmethod
    def render_index(index):
        extra_args = [repr(col.name) for col in index.columns]
        if index.unique:
            extra_args.append('unique=True')
        return 'Index({0!r}, {1})'.format(index.name, ', '.join(extra_args))

    def render_column(self, column, show_name):


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

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