make migrate.changeset.databases PEP-8 clean and add it to the API docs

docs/api.rst

@@ -9,13 +9,54 @@ Module :mod:`migrate.changeset`
    :members:
    :synopsis: Database changeset management
 
-Module :mod:`migrate.changeset.ansisql`
+Module :mod:`ansisql <migrate.changeset.ansisql>`
----------------------------------------
+-------------------------------------------------
 
 .. automodule:: migrate.changeset.ansisql
    :members:
    :synopsis: Standard SQL implementation for altering database schemas
 
+Module :mod:`databases <migrate.changeset.databases>`
+-----------------------------------------------------
+
+.. automodule:: migrate.changeset.databases
+   :members:
+   :synopsis: Database specific changeset implementations
+
+Module :mod:`mysql <migrate.changeset.databases.mysql>`
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. automodule:: migrate.changeset.databases.mysql
+   :members:
+   :synopsis: MySQL database specific changeset implementations
+
+Module :mod:`oracle <migrate.changeset.databases.oracle>`
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. automodule:: migrate.changeset.databases.oracle
+   :members:
+   :synopsis: Oracle database specific changeset implementations
+
+Module :mod:`postgres <migrate.changeset.databases.postgres>`
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. automodule:: migrate.changeset.databases.postgres
+   :members:
+   :synopsis: PostgreSQL database specific changeset implementations
+
+Module :mod:`sqlite <migrate.changeset.databases.slite>`
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. automodule:: migrate.changeset.databases.sqlite
+   :members:
+   :synopsis: SQLite database specific changeset implementations
+
+Module :mod:`visitor <migrate.changeset.databases.visitor>`
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. automodule:: migrate.changeset.databases.visitor
+   :members:
+
 Module :mod:`migrate.versioning`
 ================================
 

migrate/changeset/databases/__init__.py

@@ -1,3 +1,7 @@
+"""
+   This module contains database dialect specific changeset
+   implementations.
+"""
 __all__=[
 'postgres',
 'sqlite',

migrate/changeset/databases/mysql.py

@@ -1,52 +1,74 @@
-from migrate.changeset import ansisql,exceptions
+"""
+   MySQL database specific implementations of changeset classes.
+"""
+
+from migrate.changeset import ansisql, exceptions
 from sqlalchemy.databases import mysql as sa_base
 #import sqlalchemy as sa
 
 MySQLSchemaGenerator = sa_base.MySQLSchemaGenerator
 
-class MySQLColumnGenerator(MySQLSchemaGenerator,ansisql.ANSIColumnGenerator):
+
+class MySQLColumnGenerator(MySQLSchemaGenerator, ansisql.ANSIColumnGenerator):
+
     def _do_quote_table_identifier(self, identifier):
         return '%s'%identifier
     pass
+
+
 class MySQLColumnDropper(ansisql.ANSIColumnDropper):
+
     def _do_quote_table_identifier(self, identifier):
         return '%s'%identifier
+
     def _do_quote_column_identifier(self, identifier):
         return '%s'%identifier
 
-class MySQLSchemaChanger(MySQLSchemaGenerator,ansisql.ANSISchemaChanger):
+
-    def visit_column(self,delta):
+class MySQLSchemaChanger(MySQLSchemaGenerator, ansisql.ANSISchemaChanger):
+
+    def visit_column(self, delta):
         keys = delta.keys()
         if 'type' in keys or 'nullable' in keys or 'name' in keys:
-            self._run_subvisit(delta,self._visit_column_change)
+            self._run_subvisit(delta, self._visit_column_change)
         if 'server_default' in keys:
             # Column name might have changed above
-            col_name = delta.get('name',delta.current_name)
+            col_name = delta.get('name', delta.current_name)
-            self._run_subvisit(delta,self._visit_column_default,col_name=col_name)
+            self._run_subvisit(delta, self._visit_column_default,
-    def _visit_column_change(self,table_name,col_name,delta):
+                               col_name=col_name)
-        if not hasattr(delta,'result_column'):
+
-            # Mysql needs the whole column definition, not just a lone name/type
+    def _visit_column_change(self, table_name, col_name, delta):
+        if not hasattr(delta, 'result_column'):
+            # Mysql needs the whole column definition, not just a lone
+            # name/type
             raise exceptions.NotSupportedError(
                 "A column object is required to do this")
 
         column = delta.result_column
-        if not column.table: column.table = delta.table # needed by get_column_specification
+        # needed by get_column_specification
+        if not column.table:
+            column.table = delta.table
         colspec = self.get_column_specification(column)
         self.start_alter_table(table_name)
         self.append("CHANGE COLUMN ")
         self.append(col_name)
         self.append(' ')
         self.append(colspec)
-    def visit_index(self,param):
+
+    def visit_index(self, param):
         # If MySQL can do this, I can't find how
         raise exceptions.NotSupportedError("MySQL cannot rename indexes")
+
     def _do_quote_table_identifier(self, identifier):
         return '%s'%identifier
 
+
 class MySQLConstraintGenerator(ansisql.ANSIConstraintGenerator):
+
     def _do_quote_table_identifier(self, identifier):
         return '%s'%identifier
 
+
 class MySQLConstraintDropper(ansisql.ANSIConstraintDropper):
     #def visit_constraint(self,constraint):
     #    if isinstance(constraint,sqlalchemy.schema.PrimaryKeyConstraint):
@@ -54,12 +76,13 @@ class MySQLConstraintDropper(ansisql.ANSIConstraintDropper):
     #    elif isinstance(constraint,sqlalchemy.schema.ForeignKeyConstraint):
     #        return self._visit_constraint_fk(constraint)
     #    return super(MySQLConstraintDropper,self).visit_constraint(constraint)
-    def visit_migrate_primary_key_constraint(self,constraint):
+
+    def visit_migrate_primary_key_constraint(self, constraint):
         self.start_alter_table(constraint)
         self.append("DROP PRIMARY KEY")
         self.execute()
 
-    def visit_migrate_foreign_key_constraint(self,constraint):
+    def visit_migrate_foreign_key_constraint(self, constraint):
         self.start_alter_table(constraint)
         self.append("DROP FOREIGN KEY ")
         self.append(constraint.name)
@@ -68,6 +91,7 @@ class MySQLConstraintDropper(ansisql.ANSIConstraintDropper):
     def _do_quote_table_identifier(self, identifier):
         return '%s'%identifier
 
+
 class MySQLDialect(ansisql.ANSIDialect):
     columngenerator = MySQLColumnGenerator
     columndropper = MySQLColumnDropper

migrate/changeset/databases/oracle.py

@@ -1,54 +1,74 @@
-from migrate.changeset import ansisql,exceptions
+"""
+   Oracle database specific implementations of changeset classes.
+"""
+
+from migrate.changeset import ansisql, exceptions
 from sqlalchemy.databases import oracle as sa_base
 import sqlalchemy as sa
 
 OracleSchemaGenerator = sa_base.OracleSchemaGenerator
 
-class OracleColumnGenerator(OracleSchemaGenerator,ansisql.ANSIColumnGenerator):
+
+class OracleColumnGenerator(OracleSchemaGenerator,
+                            ansisql.ANSIColumnGenerator):
     pass
+
+
 class OracleColumnDropper(ansisql.ANSIColumnDropper):
     pass
-class OracleSchemaChanger(OracleSchemaGenerator,ansisql.ANSISchemaChanger):
+
-    def get_column_specification(self,column,**kwargs):
+
+class OracleSchemaChanger(OracleSchemaGenerator, ansisql.ANSISchemaChanger):
+
+    def get_column_specification(self, column, **kwargs):
         # Ignore the NOT NULL generated
-        override_nullable = kwargs.pop('override_nullable',None)
+        override_nullable = kwargs.pop('override_nullable', None)
         if override_nullable:
             orig = column.nullable
             column.nullable = True
-        ret=super(OracleSchemaChanger,self).get_column_specification(column,**kwargs)
+        ret = super(OracleSchemaChanger, self).get_column_specification(
+            column, **kwargs)
         if override_nullable:
             column.nullable = orig
         return ret
 
-    def visit_column(self,delta):
+    def visit_column(self, delta):
         keys = delta.keys()
-        if 'type' in keys or 'nullable' in keys or 'default' in keys or 'server_default' in keys:
+        if 'type' in keys or 'nullable' in keys or 'default' in keys \
-            self._run_subvisit(delta,self._visit_column_change)
+                or 'server_default' in keys:
+            self._run_subvisit(delta, self._visit_column_change)
         if 'name' in keys:
-            self._run_subvisit(delta,self._visit_column_name)
+            self._run_subvisit(delta, self._visit_column_name)
-    def _visit_column_change(self,table_name,col_name,delta):
+
-        if not hasattr(delta,'result_column'):
+    def _visit_column_change(self, table_name, col_name, delta):
-            # Oracle needs the whole column definition, not just a lone name/type
+        if not hasattr(delta, 'result_column'):
+            # Oracle needs the whole column definition, not just a
+            # lone name/type
             raise exceptions.NotSupportedError(
                 "A column object is required to do this")
 
         column = delta.result_column
-        # Oracle cannot drop a default once created, but it can set it to null. 
+        # Oracle cannot drop a default once created, but it can set it
-        # We'll do that if default=None
+        # to null.  We'll do that if default=None
-        # http://forums.oracle.com/forums/message.jspa?messageID=1273234#1273234
+        # http://forums.oracle.com/forums/message.jspa?\
-        dropdefault_hack = (column.server_default is None and 'server_default' in delta.keys())
+        # messageID=1273234#1273234
-        # Oracle apparently doesn't like it when we say "not null" if the
+        dropdefault_hack = (column.server_default is None \
-        # column's already not null. Fudge it, so we don't need a new function
+                                and 'server_default' in delta.keys())
-        notnull_hack = ((not column.nullable) and ('nullable' not in delta.keys()))
+        # Oracle apparently doesn't like it when we say "not null" if
-        # We need to specify NULL if we're removing a NOT NULL constraint
+        # the column's already not null. Fudge it, so we don't need a
+        # new function
+        notnull_hack = ((not column.nullable) \
+                            and ('nullable' not in delta.keys()))
+        # We need to specify NULL if we're removing a NOT NULL
+        # constraint
         null_hack = (column.nullable and ('nullable' in delta.keys()))
 
-                
         if dropdefault_hack:
             column.server_default = sa.PassiveDefault(sa.sql.null())
         if notnull_hack:
             column.nullable = True
-        colspec=self.get_column_specification(column,override_nullable=null_hack)
+        colspec=self.get_column_specification(column,
+                                              override_nullable=null_hack)
         if null_hack:
             colspec += ' NULL'
         if notnull_hack:
@@ -59,18 +79,28 @@ class OracleSchemaChanger(OracleSchemaGenerator,ansisql.ANSISchemaChanger):
         self.start_alter_table(table_name)
         self.append("MODIFY ")
         self.append(colspec)
+
+
 class OracleConstraintCommon(object):
-    def get_constraint_name(self,cons):
+
+    def get_constraint_name(self, cons):
         # Oracle constraints can't guess their name like other DBs
         if not cons.name:
             raise exceptions.NotSupportedError(
                 "Oracle constraint names must be explicitly stated")
         return cons.name
-class OracleConstraintGenerator(OracleConstraintCommon,ansisql.ANSIConstraintGenerator):
+
+
+class OracleConstraintGenerator(OracleConstraintCommon,
+                                ansisql.ANSIConstraintGenerator):
     pass
-class OracleConstraintDropper(OracleConstraintCommon,ansisql.ANSIConstraintDropper):
+
+
+class OracleConstraintDropper(OracleConstraintCommon,
+                              ansisql.ANSIConstraintDropper):
     pass
 
+
 class OracleDialect(ansisql.ANSIDialect):
     columngenerator = OracleColumnGenerator
     columndropper = OracleColumnDropper

migrate/changeset/databases/postgres.py

@@ -1,44 +1,53 @@
+"""
+   `PostgreSQL`_ database specific implementations of changeset classes.
+
+   .. _`PostgreSQL`: http://www.postgresql.org/
+"""
 from migrate.changeset import ansisql
 from sqlalchemy.databases import postgres as sa_base
 #import sqlalchemy as sa
 
+
 PGSchemaGenerator = sa_base.PGSchemaGenerator
 
+
 class PGSchemaGeneratorMixin(object):
+    """Common code used by the PostgreSQL specific classes."""
+
     def _do_quote_table_identifier(self, identifier):
         return identifier
+
     def _do_quote_column_identifier(self, identifier):
         return '"%s"'%identifier
 
-class PGColumnGenerator(PGSchemaGenerator,ansisql.ANSIColumnGenerator, PGSchemaGeneratorMixin):
+
-    def _do_quote_table_identifier(self, identifier):
+class PGColumnGenerator(PGSchemaGenerator, ansisql.ANSIColumnGenerator,
-        return identifier
+                        PGSchemaGeneratorMixin):
-    def _do_quote_column_identifier(self, identifier):
+    """PostgreSQL column generator implementation."""
-        return '"%s"'%identifier
+    pass
+
 
 class PGColumnDropper(ansisql.ANSIColumnDropper, PGSchemaGeneratorMixin):
-    def _do_quote_table_identifier(self, identifier):
+    """PostgreSQL column dropper implementation."""
-        return identifier
+    pass
-    def _do_quote_column_identifier(self, identifier):
+
-        return '"%s"'%identifier
 
 class PGSchemaChanger(ansisql.ANSISchemaChanger, PGSchemaGeneratorMixin):
-    def _do_quote_table_identifier(self, identifier):
+    """PostgreSQL schema changer implementation."""
-        return identifier
+    pass
-    def _do_quote_column_identifier(self, identifier):
-        return '"%s"'%identifier
 
-class PGConstraintGenerator(ansisql.ANSIConstraintGenerator, PGSchemaGeneratorMixin):
-    def _do_quote_table_identifier(self, identifier):
-        return identifier
-    def _do_quote_column_identifier(self, identifier):
-        return '"%s"'%identifier
 
-class PGConstraintDropper(ansisql.ANSIConstraintDropper, PGSchemaGeneratorMixin):
+class PGConstraintGenerator(ansisql.ANSIConstraintGenerator,
-    def _do_quote_table_identifier(self, identifier):
+                            PGSchemaGeneratorMixin):
-        return identifier
+    """PostgreSQL constraint generator implementation."""
-    def _do_quote_column_identifier(self, identifier):
+    pass
-        return '"%s"'%identifier
+
+
+class PGConstraintDropper(ansisql.ANSIConstraintDropper,
+                          PGSchemaGeneratorMixin):
+    """PostgreSQL constaint dropper implementation."""
+    pass
+
 
 class PGDialect(ansisql.ANSIDialect):
     columngenerator = PGColumnGenerator

migrate/changeset/databases/sqlite.py

@@ -1,11 +1,18 @@
-from migrate.changeset import ansisql,constraint,exceptions
+"""
+   `SQLite`_ database specific implementations of changeset classes.
+
+   .. _`SQLite`: http://www.sqlite.org/
+"""
+from migrate.changeset import ansisql, constraint, exceptions
 from sqlalchemy.databases import sqlite as sa_base
 from sqlalchemy import Table, MetaData
 #import sqlalchemy as sa
 
 SQLiteSchemaGenerator = sa_base.SQLiteSchemaGenerator
 
+
 class SQLiteHelper(object):
+
     def visit_column(self, param):
         try:
             table = self._to_table(param.table)
@@ -24,50 +31,61 @@ class SQLiteHelper(object):
         self.append('DROP TABLE migration_tmp')
         self.execute()
 
-class SQLiteColumnGenerator(SQLiteSchemaGenerator,ansisql.ANSIColumnGenerator):
+
+class SQLiteColumnGenerator(SQLiteSchemaGenerator,
+                            ansisql.ANSIColumnGenerator):
     pass
 
+
 class SQLiteColumnDropper(SQLiteHelper, ansisql.ANSIColumnDropper):
-    def _modify_table(self,table, column):
+
+    def _modify_table(self, table, column):
         del table.columns[column.name]
-        columns = ','.join([c.name for c in table.columns])
+        return 'INSERT INTO %(table_name)s SELECT %s from migration_tmp' % \
-        return 'INSERT INTO %(table_name)s SELECT ' + columns + ' from migration_tmp'
+            ','.join([c.name for c in table.columns])
+
 
 class SQLiteSchemaChanger(SQLiteHelper, ansisql.ANSISchemaChanger):
-    def _not_supported(self,op):
+
+    def _not_supported(self, op):
         raise exceptions.NotSupportedError("SQLite does not support "
             "%s; see http://www.sqlite.org/lang_altertable.html"%op)
 
     def _modify_table(self, table, delta):
         column = table.columns[delta.current_name]
-        for k,v in delta.items():
+        for k, v in delta.items():
             setattr(column, k, v)
         return 'INSERT INTO %(table_name)s SELECT * from migration_tmp'
 
-    def visit_index(self,param):
+    def visit_index(self, param):
         self._not_supported('ALTER INDEX')
 
     def _do_quote_column_identifier(self, identifier):
         return '"%s"'%identifier
 
+
 class SQLiteConstraintGenerator(ansisql.ANSIConstraintGenerator):
-    def visit_migrate_primary_key_constraint(self,constraint):
+
+    def visit_migrate_primary_key_constraint(self, constraint):
         tmpl = "CREATE UNIQUE INDEX %s ON %s ( %s )"
         cols = ','.join([c.name for c in constraint.columns])
         tname = constraint.table.name
         name = constraint.name
-        msg = tmpl%(name,tname,cols)
+        msg = tmpl % (name, tname, cols)
         self.append(msg)
         self.execute()
 
+
 class SQLiteConstraintDropper(ansisql.ANSIColumnDropper):
-    def visit_migrate_primary_key_constraint(self,constraint):
+
+    def visit_migrate_primary_key_constraint(self, constraint):
         tmpl = "DROP INDEX %s "
         name = constraint.name
-        msg = tmpl%(name)
+        msg = tmpl % (name)
         self.append(msg)
         self.execute()
 
+
 class SQLiteDialect(ansisql.ANSIDialect):
     columngenerator = SQLiteColumnGenerator
     columndropper = SQLiteColumnDropper

migrate/changeset/databases/visitor.py

@@ -1,20 +1,34 @@
+"""
+   Module for visitor class mapping.
+"""
 import sqlalchemy as sa
-from migrate.changeset.databases import sqlite,postgres,mysql,oracle
+from migrate.changeset.databases import sqlite, postgres, mysql, oracle
 from migrate.changeset import ansisql
 
 # Map SA dialects to the corresponding Migrate extensions
 dialects = {
-    sa.engine.default.DefaultDialect : ansisql.ANSIDialect,
+    sa.engine.default.DefaultDialect: ansisql.ANSIDialect,
-    sa.databases.sqlite.SQLiteDialect : sqlite.SQLiteDialect,
+    sa.databases.sqlite.SQLiteDialect: sqlite.SQLiteDialect,
-    sa.databases.postgres.PGDialect : postgres.PGDialect,
+    sa.databases.postgres.PGDialect: postgres.PGDialect,
-    sa.databases.mysql.MySQLDialect : mysql.MySQLDialect,
+    sa.databases.mysql.MySQLDialect: mysql.MySQLDialect,
-    sa.databases.oracle.OracleDialect : oracle.OracleDialect,
+    sa.databases.oracle.OracleDialect: oracle.OracleDialect,
 }
 
-def get_engine_visitor(engine,name):
-    return get_dialect_visitor(engine.dialect,name)
 
-def get_dialect_visitor(sa_dialect,name):
+def get_engine_visitor(engine, name):
+    """
+    Get the visitor implementation for the given database engine.
+    """
+    return get_dialect_visitor(engine.dialect, name)
+
+
+def 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.
+    """
     sa_dialect_cls = sa_dialect.__class__
     migrate_dialect_cls = dialects[sa_dialect_cls]
     return migrate_dialect_cls.visitor(name)