morro

sqlalchemy/engine/ddl.py

@@ -0,0 +1,128 @@
+# engine/ddl.py
+# Copyright (C) 2009, 2010 Michael Bayer mike_mp@zzzcomputing.com
+#
+# This module is part of SQLAlchemy and is released under
+# the MIT License: http://www.opensource.org/licenses/mit-license.php
+
+"""Routines to handle CREATE/DROP workflow."""
+
+from sqlalchemy import engine, schema
+from sqlalchemy.sql import util as sql_util
+
+
+class DDLBase(schema.SchemaVisitor):
+    def __init__(self, connection):
+        self.connection = connection
+
+class SchemaGenerator(DDLBase):
+    def __init__(self, dialect, connection, checkfirst=False, tables=None, **kwargs):
+        super(SchemaGenerator, self).__init__(connection, **kwargs)
+        self.checkfirst = checkfirst
+        self.tables = tables and set(tables) or None
+        self.preparer = dialect.identifier_preparer
+        self.dialect = dialect
+
+    def _can_create(self, table):
+        self.dialect.validate_identifier(table.name)
+        if table.schema:
+            self.dialect.validate_identifier(table.schema)
+        return not self.checkfirst or not self.dialect.has_table(self.connection, table.name, schema=table.schema)
+
+    def visit_metadata(self, metadata):
+        if self.tables:
+            tables = self.tables
+        else:
+            tables = metadata.tables.values()
+        collection = [t for t in sql_util.sort_tables(tables) if self._can_create(t)]
+        
+        for listener in metadata.ddl_listeners['before-create']:
+            listener('before-create', metadata, self.connection, tables=collection)
+            
+        for table in collection:
+            self.traverse_single(table)
+
+        for listener in metadata.ddl_listeners['after-create']:
+            listener('after-create', metadata, self.connection, tables=collection)
+
+    def visit_table(self, table):
+        for listener in table.ddl_listeners['before-create']:
+            listener('before-create', table, self.connection)
+
+        for column in table.columns:
+            if column.default is not None:
+                self.traverse_single(column.default)
+
+        self.connection.execute(schema.CreateTable(table))
+
+        if hasattr(table, 'indexes'):
+            for index in table.indexes:
+                self.traverse_single(index)
+
+        for listener in table.ddl_listeners['after-create']:
+            listener('after-create', table, self.connection)
+
+    def visit_sequence(self, sequence):
+        if self.dialect.supports_sequences:
+            if ((not self.dialect.sequences_optional or
+                 not sequence.optional) and
+                (not self.checkfirst or
+                 not self.dialect.has_sequence(self.connection, sequence.name, schema=sequence.schema))):
+                self.connection.execute(schema.CreateSequence(sequence))
+
+    def visit_index(self, index):
+        self.connection.execute(schema.CreateIndex(index))
+
+
+class SchemaDropper(DDLBase):
+    def __init__(self, dialect, connection, checkfirst=False, tables=None, **kwargs):
+        super(SchemaDropper, self).__init__(connection, **kwargs)
+        self.checkfirst = checkfirst
+        self.tables = tables
+        self.preparer = dialect.identifier_preparer
+        self.dialect = dialect
+
+    def visit_metadata(self, metadata):
+        if self.tables:
+            tables = self.tables
+        else:
+            tables = metadata.tables.values()
+        collection = [t for t in reversed(sql_util.sort_tables(tables)) if self._can_drop(t)]
+        
+        for listener in metadata.ddl_listeners['before-drop']:
+            listener('before-drop', metadata, self.connection, tables=collection)
+        
+        for table in collection:
+            self.traverse_single(table)
+
+        for listener in metadata.ddl_listeners['after-drop']:
+            listener('after-drop', metadata, self.connection, tables=collection)
+
+    def _can_drop(self, table):
+        self.dialect.validate_identifier(table.name)
+        if table.schema:
+            self.dialect.validate_identifier(table.schema)
+        return not self.checkfirst or self.dialect.has_table(self.connection, table.name, schema=table.schema)
+
+    def visit_index(self, index):
+        self.connection.execute(schema.DropIndex(index))
+
+    def visit_table(self, table):
+        for listener in table.ddl_listeners['before-drop']:
+            listener('before-drop', table, self.connection)
+
+        for column in table.columns:
+            if column.default is not None:
+                self.traverse_single(column.default)
+
+        self.connection.execute(schema.DropTable(table))
+
+        for listener in table.ddl_listeners['after-drop']:
+            listener('after-drop', table, self.connection)
+
+    def visit_sequence(self, sequence):
+        if self.dialect.supports_sequences:
+            if ((not self.dialect.sequences_optional or
+                 not sequence.optional) and
+                (not self.checkfirst or
+                 self.dialect.has_sequence(self.connection, sequence.name, schema=sequence.schema))):
+                self.connection.execute(schema.DropSequence(sequence))