Module migrate.changeset – Schema changes

Module migrate.changeset – Schema migration API

This module extends SQLAlchemy and provides additional DDL [1] support.

[1]	SQL Data Definition Language

Module ansisql – Standard SQL implementation

Extensions to SQLAlchemy for altering existing tables.

At the moment, this isn’t so much based off of ANSI as much as things that just happen to work with multiple databases.

class migrate.changeset.ansisql.ANSIColumnDropper(dialect, connection, **kw)

Extends ANSI SQL dropper for column dropping (ALTER TABLE DROP COLUMN).

visit_column(column)

Drop a column from its table.

Parameters:column (sqlalchemy.Column) – the column object

class migrate.changeset.ansisql.ANSIColumnGenerator(dialect, connection, **kw)

Extends ansisql generator for column creation (alter table add col)

visit_column(column)

Create a column (table already exists).

Parameters:column (sqlalchemy.Column instance) – column object

class migrate.changeset.ansisql.ANSIConstraintCommon(dialect, connection, **kw)

Migrate’s constraints require a separate creation function from SA’s: Migrate’s constraints are created independently of a table; SA’s are created at the same time as the table.

get_constraint_name(cons)

Gets a name for the given constraint.

If the name is already set it will be used otherwise the constraint’s autoname method is used.

Parameters:cons – constraint object

class migrate.changeset.ansisql.ANSISchemaChanger(dialect, connection, **kw)

Manages changes to existing schema elements.

Note that columns are schema elements; ALTER TABLE ADD COLUMN is in SchemaGenerator.

All items may be renamed. Columns can also have many of their properties - type, for example - changed.

Each function is passed a tuple, containing (object, name); where object is a type of object you’d expect for that function (ie. table for visit_table) and name is the object’s new name. NONE means the name is unchanged.

start_alter_column(table, col_name)

Starts ALTER COLUMN

visit_column(delta)

Rename/change a column.

visit_index(index)

Rename an index

visit_table(table)

Rename a table. Other ops aren’t supported.

class migrate.changeset.ansisql.AlterTableVisitor(dialect, connection, **kw)

Common operations for ALTER TABLE statements.

append(s)

Append content to the SchemaIterator’s query buffer.

execute()

Execute the contents of the SchemaIterator’s buffer.

start_alter_table(param)

Returns the start of an ALTER TABLE SQL-Statement.

Use the param object to determine the table name and use it for building the SQL statement.

Parameters:param (sqlalchemy.Column, sqlalchemy.Index, sqlalchemy.schema.Constraint, sqlalchemy.Table, or string (table name)) – object to determine the table from

Module constraint – Constraint schema migration API

This module defines standalone schema constraint classes.

class migrate.changeset.constraint.CheckConstraint(sqltext, *args, **kwargs)

Bases: migrate.changeset.constraint.ConstraintChangeset, sqlalchemy.sql.schema.CheckConstraint

Construct CheckConstraint

Migrate’s additional parameters:

Parameters:

• sqltext (string) – Plain SQL text to check condition
• columns (list of Columns instances) – If not name is applied, you must supply this kw to autoname constraint
• table (Table instance) – If columns are passed as strings, this kw is required

classmethod argument_for(dialect_name, argument_name, default)

Add a new kind of dialect-specific keyword argument for this class.

E.g.:

Index.argument_for("mydialect", "length", None)

some_index = Index('a', 'b', mydialect_length=5)

The DialectKWArgs.argument_for() method is a per-argument way adding extra arguments to the DefaultDialect.construct_arguments dictionary. This dictionary provides a list of argument names accepted by various schema-level constructs on behalf of a dialect.

New dialects should typically specify this dictionary all at once as a data member of the dialect class. The use case for ad-hoc addition of argument names is typically for end-user code that is also using a custom compilation scheme which consumes the additional arguments.

Parameters:

• dialect_name – name of a dialect. The dialect must be locatable, else a NoSuchModuleError is raised. The dialect must also include an existing DefaultDialect.construct_arguments collection, indicating that it participates in the keyword-argument validation and default system, else ArgumentError is raised. If the dialect does not include this collection, then any keyword argument can be specified on behalf of this dialect already. All dialects packaged within SQLAlchemy include this collection, however for third party dialects, support may vary.
• argument_name – name of the parameter.
• default – default value of the parameter.

New in version 0.9.4.

contains_column(col)

Return True if this constraint contains the given column.

Note that this object also contains an attribute .columns which is a ColumnCollection of Column objects.

create(*a, **kw)

Create the constraint in the database.

Parameters:

• engine (sqlalchemy.engine.base.Engine) – the database engine to use. If this is None the instance’s engine will be used
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

drop(*a, **kw)

Drop the constraint from the database.

Parameters:

• engine (sqlalchemy.engine.base.Engine) – the database engine to use. If this is None the instance’s engine will be used
• cascade (bool) – Issue CASCADE drop if database supports it
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

Returns:

Instance with cleared columns

get_children(**kwargs)

used to allow SchemaVisitor access

dialect_kwargs

A collection of keyword arguments specified as dialect-specific options to this construct.

The arguments are present here in their original <dialect>_<kwarg> format. Only arguments that were actually passed are included; unlike the DialectKWArgs.dialect_options collection, which contains all options known by this dialect including defaults.

The collection is also writable; keys are accepted of the form <dialect>_<kwarg> where the value will be assembled into the list of options.

New in version 0.9.2.

Changed in version 0.9.4: The DialectKWArgs.dialect_kwargs collection is now writable.

See also

DialectKWArgs.dialect_options - nested dictionary form

dialect_options

A collection of keyword arguments specified as dialect-specific options to this construct.

This is a two-level nested registry, keyed to <dialect_name> and <argument_name>. For example, the postgresql_where argument would be locatable as:

arg = my_object.dialect_options['postgresql']['where']

New in version 0.9.2.

See also

DialectKWArgs.dialect_kwargs - flat dictionary form

info

Info dictionary associated with the object, allowing user-defined data to be associated with this SchemaItem.

The dictionary is automatically generated when first accessed. It can also be specified in the constructor of some objects, such as Table and Column.

kwargs

A synonym for DialectKWArgs.dialect_kwargs.

quote

Return the value of the quote flag passed to this schema object, for those schema items which have a name field.

Deprecated since version 0.9: Use <obj>.name.quote

class migrate.changeset.constraint.ConstraintChangeset

Bases: object

Base class for Constraint classes.

create(*a, **kw)

Create the constraint in the database.

Parameters:

• engine (sqlalchemy.engine.base.Engine) – the database engine to use. If this is None the instance’s engine will be used
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

drop(*a, **kw)

Drop the constraint from the database.

Parameters:

• engine (sqlalchemy.engine.base.Engine) – the database engine to use. If this is None the instance’s engine will be used
• cascade (bool) – Issue CASCADE drop if database supports it
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

Returns:

Instance with cleared columns

class migrate.changeset.constraint.ForeignKeyConstraint(columns, refcolumns, *args, **kwargs)

Bases: migrate.changeset.constraint.ConstraintChangeset, sqlalchemy.sql.schema.ForeignKeyConstraint

Construct ForeignKeyConstraint

Migrate’s additional parameters:

Parameters:

• columns (list of strings or Column instances) – Columns in constraint
• refcolumns (list of strings or Column instances) – Columns that this FK reffers to in another table.
• table (Table instance) – If columns are passed as strings, this kw is required

classmethod argument_for(dialect_name, argument_name, default)

Add a new kind of dialect-specific keyword argument for this class.

E.g.:

Index.argument_for("mydialect", "length", None)

some_index = Index('a', 'b', mydialect_length=5)

The DialectKWArgs.argument_for() method is a per-argument way adding extra arguments to the DefaultDialect.construct_arguments dictionary. This dictionary provides a list of argument names accepted by various schema-level constructs on behalf of a dialect.

New dialects should typically specify this dictionary all at once as a data member of the dialect class. The use case for ad-hoc addition of argument names is typically for end-user code that is also using a custom compilation scheme which consumes the additional arguments.

Parameters:

• dialect_name – name of a dialect. The dialect must be locatable, else a NoSuchModuleError is raised. The dialect must also include an existing DefaultDialect.construct_arguments collection, indicating that it participates in the keyword-argument validation and default system, else ArgumentError is raised. If the dialect does not include this collection, then any keyword argument can be specified on behalf of this dialect already. All dialects packaged within SQLAlchemy include this collection, however for third party dialects, support may vary.
• argument_name – name of the parameter.
• default – default value of the parameter.

New in version 0.9.4.

autoname()

Mimic the database’s automatic constraint names

contains_column(col)

Return True if this constraint contains the given column.

Note that this object also contains an attribute .columns which is a ColumnCollection of Column objects.

create(*a, **kw)

Create the constraint in the database.

Parameters:

• engine (sqlalchemy.engine.base.Engine) – the database engine to use. If this is None the instance’s engine will be used
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

drop(*a, **kw)

Drop the constraint from the database.

Parameters:

• engine (sqlalchemy.engine.base.Engine) – the database engine to use. If this is None the instance’s engine will be used
• cascade (bool) – Issue CASCADE drop if database supports it
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

Returns:

Instance with cleared columns

get_children(**kwargs)

used to allow SchemaVisitor access

column_keys

Return a list of string keys representing the local columns in this ForeignKeyConstraint.

This list is either the original string arguments sent to the constructor of the ForeignKeyConstraint, or if the constraint has been initialized with Column objects, is the string .key of each element.

New in version 1.0.0.

dialect_kwargs

A collection of keyword arguments specified as dialect-specific options to this construct.

The arguments are present here in their original <dialect>_<kwarg> format. Only arguments that were actually passed are included; unlike the DialectKWArgs.dialect_options collection, which contains all options known by this dialect including defaults.

The collection is also writable; keys are accepted of the form <dialect>_<kwarg> where the value will be assembled into the list of options.

New in version 0.9.2.

Changed in version 0.9.4: The DialectKWArgs.dialect_kwargs collection is now writable.

See also

DialectKWArgs.dialect_options - nested dictionary form

dialect_options

A collection of keyword arguments specified as dialect-specific options to this construct.

This is a two-level nested registry, keyed to <dialect_name> and <argument_name>. For example, the postgresql_where argument would be locatable as:

arg = my_object.dialect_options['postgresql']['where']

New in version 0.9.2.

See also

DialectKWArgs.dialect_kwargs - flat dictionary form

info

Info dictionary associated with the object, allowing user-defined data to be associated with this SchemaItem.

The dictionary is automatically generated when first accessed. It can also be specified in the constructor of some objects, such as Table and Column.

kwargs

A synonym for DialectKWArgs.dialect_kwargs.

quote

Return the value of the quote flag passed to this schema object, for those schema items which have a name field.

Deprecated since version 0.9: Use <obj>.name.quote

referred_table

The Table object to which this ForeignKeyConstraint references.

This is a dynamically calculated attribute which may not be available if the constraint and/or parent table is not yet associated with a metadata collection that contains the referred table.

New in version 1.0.0.

class migrate.changeset.constraint.PrimaryKeyConstraint(*cols, **kwargs)

Bases: migrate.changeset.constraint.ConstraintChangeset, sqlalchemy.sql.schema.PrimaryKeyConstraint

Construct PrimaryKeyConstraint

Migrate’s additional parameters:

Parameters:

• cols (strings or Column instances) – Columns in constraint.
• table (Table instance) – If columns are passed as strings, this kw is required

classmethod argument_for(dialect_name, argument_name, default)

Add a new kind of dialect-specific keyword argument for this class.

E.g.:

Index.argument_for("mydialect", "length", None)

some_index = Index('a', 'b', mydialect_length=5)

The DialectKWArgs.argument_for() method is a per-argument way adding extra arguments to the DefaultDialect.construct_arguments dictionary. This dictionary provides a list of argument names accepted by various schema-level constructs on behalf of a dialect.

New dialects should typically specify this dictionary all at once as a data member of the dialect class. The use case for ad-hoc addition of argument names is typically for end-user code that is also using a custom compilation scheme which consumes the additional arguments.

Parameters:

• dialect_name – name of a dialect. The dialect must be locatable, else a NoSuchModuleError is raised. The dialect must also include an existing DefaultDialect.construct_arguments collection, indicating that it participates in the keyword-argument validation and default system, else ArgumentError is raised. If the dialect does not include this collection, then any keyword argument can be specified on behalf of this dialect already. All dialects packaged within SQLAlchemy include this collection, however for third party dialects, support may vary.
• argument_name – name of the parameter.
• default – default value of the parameter.

New in version 0.9.4.

autoname()

Mimic the database’s automatic constraint names

contains_column(col)

Return True if this constraint contains the given column.

Note that this object also contains an attribute .columns which is a ColumnCollection of Column objects.

create(*a, **kw)

Create the constraint in the database.

Parameters:

• engine (sqlalchemy.engine.base.Engine) – the database engine to use. If this is None the instance’s engine will be used
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

drop(*a, **kw)

Drop the constraint from the database.

Parameters:

• engine (sqlalchemy.engine.base.Engine) – the database engine to use. If this is None the instance’s engine will be used
• cascade (bool) – Issue CASCADE drop if database supports it
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

Returns:

Instance with cleared columns

get_children(**kwargs)

used to allow SchemaVisitor access

dialect_kwargs

A collection of keyword arguments specified as dialect-specific options to this construct.

The arguments are present here in their original <dialect>_<kwarg> format. Only arguments that were actually passed are included; unlike the DialectKWArgs.dialect_options collection, which contains all options known by this dialect including defaults.

The collection is also writable; keys are accepted of the form <dialect>_<kwarg> where the value will be assembled into the list of options.

New in version 0.9.2.

Changed in version 0.9.4: The DialectKWArgs.dialect_kwargs collection is now writable.

See also

DialectKWArgs.dialect_options - nested dictionary form

dialect_options

A collection of keyword arguments specified as dialect-specific options to this construct.

This is a two-level nested registry, keyed to <dialect_name> and <argument_name>. For example, the postgresql_where argument would be locatable as:

arg = my_object.dialect_options['postgresql']['where']

New in version 0.9.2.

See also

DialectKWArgs.dialect_kwargs - flat dictionary form

info

Info dictionary associated with the object, allowing user-defined data to be associated with this SchemaItem.

The dictionary is automatically generated when first accessed. It can also be specified in the constructor of some objects, such as Table and Column.

kwargs

A synonym for DialectKWArgs.dialect_kwargs.

quote

Return the value of the quote flag passed to this schema object, for those schema items which have a name field.

Deprecated since version 0.9: Use <obj>.name.quote

class migrate.changeset.constraint.UniqueConstraint(*cols, **kwargs)

Bases: migrate.changeset.constraint.ConstraintChangeset, sqlalchemy.sql.schema.UniqueConstraint

Construct UniqueConstraint

Migrate’s additional parameters:

Parameters:

• cols (strings or Column instances) – Columns in constraint.
• table (Table instance) – If columns are passed as strings, this kw is required

New in version 0.6.0.

classmethod argument_for(dialect_name, argument_name, default)

Add a new kind of dialect-specific keyword argument for this class.

E.g.:

Index.argument_for("mydialect", "length", None)

some_index = Index('a', 'b', mydialect_length=5)

The DialectKWArgs.argument_for() method is a per-argument way adding extra arguments to the DefaultDialect.construct_arguments dictionary. This dictionary provides a list of argument names accepted by various schema-level constructs on behalf of a dialect.

New dialects should typically specify this dictionary all at once as a data member of the dialect class. The use case for ad-hoc addition of argument names is typically for end-user code that is also using a custom compilation scheme which consumes the additional arguments.

Parameters:

• dialect_name – name of a dialect. The dialect must be locatable, else a NoSuchModuleError is raised. The dialect must also include an existing DefaultDialect.construct_arguments collection, indicating that it participates in the keyword-argument validation and default system, else ArgumentError is raised. If the dialect does not include this collection, then any keyword argument can be specified on behalf of this dialect already. All dialects packaged within SQLAlchemy include this collection, however for third party dialects, support may vary.
• argument_name – name of the parameter.
• default – default value of the parameter.

New in version 0.9.4.

autoname()

Mimic the database’s automatic constraint names

contains_column(col)

Return True if this constraint contains the given column.

Note that this object also contains an attribute .columns which is a ColumnCollection of Column objects.

create(*a, **kw)

Create the constraint in the database.

Parameters:

• engine (sqlalchemy.engine.base.Engine) – the database engine to use. If this is None the instance’s engine will be used
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

drop(*a, **kw)

Drop the constraint from the database.

Parameters:

• engine (sqlalchemy.engine.base.Engine) – the database engine to use. If this is None the instance’s engine will be used
• cascade (bool) – Issue CASCADE drop if database supports it
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

Returns:

Instance with cleared columns

get_children(**kwargs)

used to allow SchemaVisitor access

dialect_kwargs

A collection of keyword arguments specified as dialect-specific options to this construct.

The arguments are present here in their original <dialect>_<kwarg> format. Only arguments that were actually passed are included; unlike the DialectKWArgs.dialect_options collection, which contains all options known by this dialect including defaults.

The collection is also writable; keys are accepted of the form <dialect>_<kwarg> where the value will be assembled into the list of options.

New in version 0.9.2.

Changed in version 0.9.4: The DialectKWArgs.dialect_kwargs collection is now writable.

See also

DialectKWArgs.dialect_options - nested dictionary form

dialect_options

A collection of keyword arguments specified as dialect-specific options to this construct.

This is a two-level nested registry, keyed to <dialect_name> and <argument_name>. For example, the postgresql_where argument would be locatable as:

arg = my_object.dialect_options['postgresql']['where']

New in version 0.9.2.

See also

DialectKWArgs.dialect_kwargs - flat dictionary form

info

Info dictionary associated with the object, allowing user-defined data to be associated with this SchemaItem.

The dictionary is automatically generated when first accessed. It can also be specified in the constructor of some objects, such as Table and Column.

kwargs

A synonym for DialectKWArgs.dialect_kwargs.

quote

Return the value of the quote flag passed to this schema object, for those schema items which have a name field.

Deprecated since version 0.9: Use <obj>.name.quote

Module databases – Database specific schema migration

This module contains database dialect specific changeset implementations.

Module mysql

MySQL database specific implementations of changeset classes.

Module firebird

Firebird database specific implementations of changeset classes.

class migrate.changeset.databases.firebird.FBColumnDropper(dialect, connection, **kw)

Firebird column dropper implementation.

visit_column(column)

Firebird supports ‘DROP col’ instead of ‘DROP COLUMN col’ syntax

Drop primary key and unique constraints if dropped column is referencing it.

class migrate.changeset.databases.firebird.FBColumnGenerator(dialect, connection, **kw)

Firebird column generator implementation.

class migrate.changeset.databases.firebird.FBConstraintDropper(dialect, connection, **kw)

Firebird constaint dropper implementation.

cascade_constraint(constraint)

Cascading constraints is not supported

class migrate.changeset.databases.firebird.FBConstraintGenerator(dialect, connection, **kw)

Firebird constraint generator implementation.

class migrate.changeset.databases.firebird.FBSchemaChanger(dialect, connection, **kw)

Firebird schema changer implementation.

visit_table(table)

Rename table not supported

Module oracle

Oracle database specific implementations of changeset classes.

Module postgres

PostgreSQL database specific implementations of changeset classes.

class migrate.changeset.databases.postgres.PGColumnDropper(dialect, connection, **kw)

PostgreSQL column dropper implementation.

class migrate.changeset.databases.postgres.PGColumnGenerator(dialect, connection, **kw)

PostgreSQL column generator implementation.

class migrate.changeset.databases.postgres.PGConstraintDropper(dialect, connection, **kw)

PostgreSQL constaint dropper implementation.

class migrate.changeset.databases.postgres.PGConstraintGenerator(dialect, connection, **kw)

PostgreSQL constraint generator implementation.

class migrate.changeset.databases.postgres.PGSchemaChanger(dialect, connection, **kw)

PostgreSQL schema changer implementation.

Module sqlite

SQLite database specific implementations of changeset classes.

class migrate.changeset.databases.sqlite.SQLiteColumnDropper(dialect, connection, **kw)

SQLite ColumnDropper

class migrate.changeset.databases.sqlite.SQLiteColumnGenerator(dialect, connection, **kw)

SQLite ColumnGenerator

class migrate.changeset.databases.sqlite.SQLiteSchemaChanger(dialect, connection, **kw)

SQLite SchemaChanger

visit_index(index)

Does not support ALTER INDEX

Module visitor

Module for visitor class mapping.

migrate.changeset.databases.visitor.get_dialect_visitor(sa_dialect, name)

Get the visitor implementation for the given dialect.

Finds the visitor implementation based on the dialect class and returns and instance initialized with the given name.

Binds dialect specific preparer to visitor.

migrate.changeset.databases.visitor.get_engine_visitor(engine, name)

Get the visitor implementation for the given database engine.

Parameters:

• engine (Engine) – SQLAlchemy Engine
• name (string) – Name of the visitor

Returns:

visitor

migrate.changeset.databases.visitor.run_single_visitor(engine, visitorcallable, element, connection=None, **kwargs)

Taken from sqlalchemy.engine.base.Engine._run_single_visitor() with support for migrate visitors.

Module schema – Additional API to SQLAlchemy for migrations

Schema module providing common schema operations.

migrate.changeset.schema.create_column(column, table=None, *p, **kw)

Create a column, given the table.

API to ChangesetColumn.create().

migrate.changeset.schema.drop_column(column, table=None, *p, **kw)

Drop a column, given the table.

API to ChangesetColumn.drop().

migrate.changeset.schema.alter_column(*p, **k)

Alter a column.

This is a helper function that creates a ColumnDelta and runs it.

Parameters:

• column – The name of the column to be altered or a ChangesetColumn column representing it.
• table – A Table or table name to for the table where the column will be changed.
• engine – The Engine to use for table reflection and schema alterations.

Returns:

A ColumnDelta instance representing the change.

migrate.changeset.schema.rename_table(table, name, engine=None, **kw)

Rename a table.

If Table instance is given, engine is not used.

API to ChangesetTable.rename().

Parameters:

• table (string or Table instance) – Table to be renamed.
• name (string) – New name for Table.
• engine (obj) – Engine instance.

migrate.changeset.schema.rename_index(index, name, table=None, engine=None, **kw)

Rename an index.

If Index instance is given, table and engine are not used.

API to ChangesetIndex.rename().

Parameters:

• index (string or Index instance) – Index to be renamed.
• name (string) – New name for index.
• table (string or Table instance) – Table to which Index is reffered.
• engine (obj) – Engine instance.

class migrate.changeset.schema.ChangesetTable

Changeset extensions to SQLAlchemy tables.

create_column(column, *p, **kw)

Creates a column.

The column parameter may be a column definition or the name of a column in this table.

API to ChangesetColumn.create()

Parameters:column (Column instance or string) – Column to be created

deregister()

Remove this table from its metadata

drop_column(column, *p, **kw)

Drop a column, given its name or definition.

API to ChangesetColumn.drop()

Parameters:column (Column instance or string) – Column to be droped

rename(name, connection=None, **kwargs)

Rename this table.

Parameters:

• name (string) – New name of the table.
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

class migrate.changeset.schema.ChangesetColumn

Changeset extensions to SQLAlchemy columns.

alter(*p, **k)

Makes a call to alter_column() for the column this method is called on.

copy_fixed(**kw)

Create a copy of this Column, with all attributes.

create(table=None, index_name=None, unique_name=None, primary_key_name=None, populate_default=True, connection=None, **kwargs)

Create this column in the database.

Assumes the given table exists. ALTER TABLE ADD COLUMN, for most databases.

Parameters:

• table (Table instance) – Table instance to create on.
• index_name (string) – Creates ChangesetIndex on this column.
• unique_name (string) – Creates UniqueConstraint on this column.
• primary_key_name (string) – Creates PrimaryKeyConstraint on this column.
• populate_default (bool) – If True, created column will be populated with defaults
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

Returns:

self

drop(table=None, connection=None, **kwargs)

Drop this column from the database, leaving its table intact.

ALTER TABLE DROP COLUMN, for most databases.

Parameters:connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

class migrate.changeset.schema.ChangesetIndex

Changeset extensions to SQLAlchemy Indexes.

rename(name, connection=None, **kwargs)

Change the name of an index.

Parameters:

• name (string) – New name of the Index.
• connection (sqlalchemy.engine.base.Connection instance) – reuse connection istead of creating new one.

class migrate.changeset.schema.ChangesetDefaultClause

Implements comparison between DefaultClause instances

class migrate.changeset.schema.ColumnDelta(*p, **kw)

Extracts the differences between two columns/column-parameters

May receive parameters arranged in several different ways:

• current_column, new_column, *p, **kw

  Additional parameters can be specified to override column differences.

• current_column, *p, **kw

  Additional parameters alter current_column. Table name is extracted from current_column object. Name is changed to current_column.name from current_name, if current_name is specified.

• current_col_name, *p, **kw

  Table kw must specified.

Parameters:

• table (string or Table instance) – Table at which current Column should be bound to. If table name is given, reflection will be used.
• metadata – A MetaData instance to store reflected table names
• engine (Engine instance) – When reflecting tables, either engine or metadata must be specified to acquire engine object.

Returns:

ColumnDelta instance provides interface for altered attributes to result_column through dict() alike object.

• ColumnDelta.result_column is altered column with new attributes
• ColumnDelta.current_name is current name of column in db

apply_diffs(diffs)

Populate dict and column object with new values

are_column_types_eq(old_type, new_type)

Compares two types to be equal

compare_1_column(col, *p, **k)

Compares one Column object

compare_2_columns(old_col, new_col, *p, **k)

Compares two Column objects

compare_parameters(current_name, *p, **k)

Compares Column objects with reflection

process_column(column)

Processes default values for column

Module migrate.versioning – Database versioning and repository management

This package provides functionality to create and manage repositories of database schema changesets and to apply these changesets to databases.

Module api – Python API commands

Module genmodel – ORM Model generator

Code to generate a Python model from a database or differences between a model and database.

Some of this is borrowed heavily from the AutoCode project at: http://code.google.com/p/sqlautocode/

class migrate.versioning.genmodel.ModelGenerator(diff, engine, declarative=False)

Various transformations from an A, B diff.

In the implementation, A tends to be called the model and B the database (although this is not true of all diffs). The diff is directionless, but transformations apply the diff in a particular direction, described in the method name.

genB2AMigration(indent=' ')

Generate a migration from B to A.

Was: toUpgradeDowngradePython Assume model (A) is most current and database (B) is out-of-date.

genBDefinition()

Generates the source code for a definition of B.

Assumes a diff where A is empty.

Was: toPython. Assume database (B) is current and model (A) is empty.

runB2A()

Goes from B to A.

Was: applyModel. Apply model (A) to current database (B).

Module pathed – Path utilities

A path/directory class.

class migrate.versioning.pathed.Pathed(path)

A class associated with a path/directory tree.

Only one instance of this class may exist for a particular file; __new__ will return an existing instance if possible

classmethod require_found(path)

Ensures a given path already exists

classmethod require_notfound(path)

Ensures a given path does not already exist

Module repository – Repository management

Module schema – Migration upgrade/downgrade

Module schemadiff – ORM Model differencing

Schema differencing support.

class migrate.versioning.schemadiff.ColDiff(col_A, col_B)

Container for differences in one Column between two Table instances, A and B.

col_A

The Column object for A.

col_B

The Column object for B.

type_A

The most generic type of the Column object in A.

type_B

The most generic type of the Column object in A.

class migrate.versioning.schemadiff.SchemaDiff(metadataA, metadataB, labelA='metadataA', labelB='metadataB', excludeTables=None)

Compute the difference between two MetaData objects.

The string representation of a SchemaDiff will summarise the changes found between the two MetaData objects.

The length of a SchemaDiff will give the number of changes found, enabling it to be used much like a boolean in expressions.

Parameters:

• metadataA – First MetaData to compare.
• metadataB – Second MetaData to compare.
• labelA – The label to use in messages about the first MetaData.
• labelB – The label to use in messages about the second MetaData.
• excludeTables – A sequence of table names to exclude.

tables_missing_from_A

A sequence of table names that were found in B but weren’t in A.

tables_missing_from_B

A sequence of table names that were found in A but weren’t in B.

tables_different

A dictionary containing information about tables that were found to be different. It maps table names to a TableDiff objects describing the differences found.

class migrate.versioning.schemadiff.TableDiff

Container for differences in one Table between two MetaData instances, A and B.

columns_missing_from_A

A sequence of column names that were found in B but weren’t in A.

columns_missing_from_B

A sequence of column names that were found in A but weren’t in B.

columns_different

A dictionary containing information about columns that were found to be different. It maps column names to a ColDiff objects describing the differences found.

migrate.versioning.schemadiff.getDiffOfModelAgainstDatabase(metadata, engine, excludeTables=None)

Return differences of model against database.

Returns:object which will evaluate to True if there are differences else False.

migrate.versioning.schemadiff.getDiffOfModelAgainstModel(metadataA, metadataB, excludeTables=None)

Return differences of model against another model.

Returns:object which will evaluate to True if there are differences else False.

Module script – Script actions

Module shell – CLI interface

Module util – Various utility functions

class migrate.versioning.util.Memoize(fn)

Memoize(fn) - an instance which acts like fn but memoizes its arguments Will only work on functions with non-mutable arguments

ActiveState Code 52201

migrate.versioning.util.asbool(obj)

Do everything to use object as bool

migrate.versioning.util.catch_known_errors(func)

Decorator that catches known api errors

migrate.versioning.util.construct_engine(engine, **opts)

New in version 0.5.4.

Constructs and returns SQLAlchemy engine.

Currently, there are 2 ways to pass create_engine options to migrate.versioning.api functions:

Parameters:

• engine (string or Engine instance) – connection string or a existing engine
• engine_dict (dict) – python dictionary of options to pass to create_engine
• engine_arg_* (string) – keyword parameters to pass to create_engine (evaluated with migrate.versioning.util.guess_obj_type())

Returns:

SQLAlchemy Engine

Note

keyword parameters override engine_dict values.

migrate.versioning.util.guess_obj_type(obj)

Do everything to guess object type from string

Tries to convert to int, bool and finally returns if not succeded.

migrate.versioning.util.load_model(dotted_name)

Import module and use module-level variable”.

Parameters:dotted_name – path to model in form of string: some.python.module:Class

Changed in version 0.5.4.

migrate.versioning.util.with_engine(func)

Decorator for migrate.versioning.api functions to safely close resources after function usage.

Passes engine parameters to construct_engine() and resulting parameter is available as kw[‘engine’].

Engine is disposed after wrapped function is executed.

Module version – Versioning management

Module exceptions – Exception definitions

Provide exception classes for migrate

exception migrate.exceptions.ApiError

Base class for API errors.

exception migrate.exceptions.ControlledSchemaError

Base class for controlled schema errors.

exception migrate.exceptions.DatabaseAlreadyControlledError

Database shouldn’t be under version control, but it is

exception migrate.exceptions.DatabaseNotControlledError

Database should be under version control, but it’s not.

exception migrate.exceptions.Error

Error base class.

exception migrate.exceptions.InvalidConstraintError

Invalid constraint error

exception migrate.exceptions.InvalidRepositoryError

Invalid repository error.

exception migrate.exceptions.InvalidScriptError

Invalid script error.

exception migrate.exceptions.InvalidVersionError

Invalid version error.

exception migrate.exceptions.KnownError

A known error condition.

exception migrate.exceptions.MigrateDeprecationWarning

Warning for deprecated features in Migrate

exception migrate.exceptions.NoSuchTableError

The table does not exist.

exception migrate.exceptions.NotSupportedError

Not supported error

exception migrate.exceptions.PathError

Base class for path errors.

exception migrate.exceptions.PathFoundError

A path with a file was required; found no file.

exception migrate.exceptions.PathNotFoundError

A path with no file was required; found a file.

exception migrate.exceptions.RepositoryError

Base class for repository errors.

exception migrate.exceptions.ScriptError

Base class for script errors.

exception migrate.exceptions.UsageError

A known error condition where help should be displayed.

exception migrate.exceptions.WrongRepositoryError

This database is under version control by another repository.