diff options
| -rw-r--r-- | doc/build/changelog/changelog_08.rst | 7 | ||||
| -rw-r--r-- | doc/build/changelog/changelog_09.rst | 7 | ||||
| -rw-r--r-- | lib/sqlalchemy/sql/compiler.py | 8 | ||||
| -rw-r--r-- | lib/sqlalchemy/sql/ddl.py | 29 | ||||
| -rw-r--r-- | test/ext/test_compiler.py | 18 |
5 files changed, 65 insertions, 4 deletions
diff --git a/doc/build/changelog/changelog_08.rst b/doc/build/changelog/changelog_08.rst index 39a8627ba..edfa4b63f 100644 --- a/doc/build/changelog/changelog_08.rst +++ b/doc/build/changelog/changelog_08.rst @@ -7,6 +7,13 @@ :version: 0.8.3 .. change:: + :tags: feature + + The :class:`.CreateColumn` construct can be appled to a custom + compilation rule which allows skipping of columns, by producing + a rule that returns ``None``. + + .. change:: :tags: bug, orm :tickets: 2807 diff --git a/doc/build/changelog/changelog_09.rst b/doc/build/changelog/changelog_09.rst index d928120f9..7e6f4e167 100644 --- a/doc/build/changelog/changelog_09.rst +++ b/doc/build/changelog/changelog_09.rst @@ -7,6 +7,13 @@ :version: 0.9.0 .. change:: + :tags: feature + + The :class:`.CreateColumn` construct can be appled to a custom + compilation rule which allows skipping of columns, by producing + a rule that returns ``None``. Also in 0.8.3. + + .. change:: :tags: bug, orm :tickets: 2807 diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py index dc3d55039..c56ca1ae4 100644 --- a/lib/sqlalchemy/sql/compiler.py +++ b/lib/sqlalchemy/sql/compiler.py @@ -2178,11 +2178,13 @@ class DDLCompiler(Compiled): for create_column in create.columns: column = create_column.element try: - text += separator - separator = ", \n" - text += "\t" + self.process(create_column, + processed = self.process(create_column, first_pk=column.primary_key and not first_pk) + if processed is not None: + text += separator + separator = ", \n" + text += "\t" + processed if column.primary_key: first_pk = True except exc.CompileError as ce: diff --git a/lib/sqlalchemy/sql/ddl.py b/lib/sqlalchemy/sql/ddl.py index 8159ca472..a0163ad7a 100644 --- a/lib/sqlalchemy/sql/ddl.py +++ b/lib/sqlalchemy/sql/ddl.py @@ -548,6 +548,35 @@ class CreateColumn(_DDLCompiles): PRIMARY KEY (x) ) + The :class:`.CreateColumn` construct can also be used to skip certain + columns when producing a ``CREATE TABLE``. This is accomplished by + creating a compilation rule that conditionally returns ``None``. + For example, to produce a + :class:`.Table` which includes the Postgresql system column ``xmin``, + but omits this column from the ``CREATE TABLE``:: + + from sqlalchemy.schema import CreateColumn + + @compiles(CreateColumn) + def skip_xmin(element, compiler, **kw): + if element.element.name == 'xmin': + return None + else: + return compiler.visit_create_column(element, **kw) + + + my_table = Table('mytable', metadata, + Column('id', Integer, primary_key=True), + Column('xmin', Integer) + ) + + Above, a :class:`.CreateTable` construct will generate a ``CREATE TABLE`` + which only includes the ``id`` column in the string; the ``xmin`` column + will be omitted. + + .. versionadded:: 0.8.3 The :class:`.CreateColumn` construct supports + skipping of columns by returning ``None`` from a custom compilation rule. + .. versionadded:: 0.8 The :class:`.CreateColumn` construct was added to support custom column creation styles. diff --git a/test/ext/test_compiler.py b/test/ext/test_compiler.py index c1f8b6258..5ed50442f 100644 --- a/test/ext/test_compiler.py +++ b/test/ext/test_compiler.py @@ -4,7 +4,7 @@ from sqlalchemy.sql.expression import ClauseElement, ColumnClause,\ FunctionElement, Select, \ BindParameter -from sqlalchemy.schema import DDLElement +from sqlalchemy.schema import DDLElement, CreateColumn, CreateTable from sqlalchemy.ext.compiler import compiles, deregister from sqlalchemy import exc from sqlalchemy.sql import table, column, visitors @@ -34,6 +34,22 @@ class UserDefinedTest(fixtures.TestBase, AssertsCompiledSQL): "SELECT >>x<<, >>y<< WHERE >>MYTHINGY!<< = :MYTHINGY!_1" ) + def test_create_column_skip(self): + @compiles(CreateColumn) + def skip_xmin(element, compiler, **kw): + if element.element.name == 'xmin': + return None + else: + return compiler.visit_create_column(element, **kw) + + t = Table('t', MetaData(), Column('a', Integer), + Column('xmin', Integer), + Column('c', Integer)) + + self.assert_compile( + CreateTable(t), + "CREATE TABLE t (a INTEGER, c INTEGER)" + ) def test_types(self): class MyType(TypeEngine): pass |