diff options
Diffstat (limited to 'lib/sqlalchemy/schema.py')
| -rw-r--r-- | lib/sqlalchemy/schema.py | 51 |
1 files changed, 31 insertions, 20 deletions
diff --git a/lib/sqlalchemy/schema.py b/lib/sqlalchemy/schema.py index 2e5a1a637..70087ee73 100644 --- a/lib/sqlalchemy/schema.py +++ b/lib/sqlalchemy/schema.py @@ -1261,7 +1261,8 @@ class Constraint(SchemaItem): __visit_name__ = 'constraint' - def __init__(self, name=None, deferrable=None, initially=None, inline_ddl=True): + def __init__(self, name=None, deferrable=None, initially=None, + _create_rule=None): """Create a SQL constraint. name @@ -1275,20 +1276,29 @@ class Constraint(SchemaItem): Optional string. If set, emit INITIALLY <value> when issuing DDL for this constraint. - inline_ddl - if True, DDL for this Constraint will be generated within the span of a - CREATE TABLE or DROP TABLE statement, when the associated table's - DDL is generated. if False, no DDL is issued within that process. - Instead, it is expected that an AddConstraint or DropConstraint - construct will be used to issue DDL for this Contraint. - The AddConstraint/DropConstraint constructs set this flag automatically - as well. + _create_rule + a callable which is passed the DDLCompiler object during + compilation. Returns True or False to signal inline generation of + this Constraint. + + The AddConstraint and DropConstraint DDL constructs provide + DDLElement's more comprehensive "conditional DDL" approach that is + passed a database connection when DDL is being issued. _create_rule + is instead called during any CREATE TABLE compilation, where there + may not be any transaction/connection in progress. However, it + allows conditional compilation of the constraint even for backends + which do not support addition of constraints through ALTER TABLE, + which currently includes SQLite. + + _create_rule is used by some types to create constraints. + Currently, its call signature is subject to change at any time. + """ self.name = name self.deferrable = deferrable self.initially = initially - self.inline_ddl = inline_ddl + self._create_rule = _create_rule @property def table(self): @@ -1364,13 +1374,13 @@ class CheckConstraint(Constraint): Can be included in the definition of a Table or Column. """ - def __init__(self, sqltext, name=None, deferrable=None, initially=None, table=None): + def __init__(self, sqltext, name=None, deferrable=None, initially=None, table=None, _create_rule=None): """Construct a CHECK constraint. sqltext - A string containing the constraint definition. Will be used - verbatim. - + A string containing the constraint definition, which will be used + verbatim, or a SQL expression construct. + name Optional, the in-database name of the constraint. @@ -1384,11 +1394,8 @@ class CheckConstraint(Constraint): """ - super(CheckConstraint, self).__init__(name, deferrable, initially) - if not isinstance(sqltext, basestring): - raise exc.ArgumentError( - "sqltext must be a string and will be used verbatim.") - self.sqltext = sqltext + super(CheckConstraint, self).__init__(name, deferrable, initially, _create_rule) + self.sqltext = expression._literal_as_text(sqltext) if table is not None: self._set_parent(table) @@ -2224,7 +2231,6 @@ class _CreateDropBase(DDLElement): self._check_ddl_on(on) self.on = on self.bind = bind - element.inline_ddl = False class CreateTable(_CreateDropBase): """Represent a CREATE TABLE statement.""" @@ -2265,6 +2271,10 @@ class AddConstraint(_CreateDropBase): __visit_name__ = "add_constraint" + def __init__(self, element, *args, **kw): + super(AddConstraint, self).__init__(element, *args, **kw) + element._create_rule = lambda compiler: False + class DropConstraint(_CreateDropBase): """Represent an ALTER TABLE DROP CONSTRAINT statement.""" @@ -2273,6 +2283,7 @@ class DropConstraint(_CreateDropBase): def __init__(self, element, cascade=False, **kw): self.cascade = cascade super(DropConstraint, self).__init__(element, **kw) + element._create_rule = lambda compiler: False def _bind_or_error(schemaitem): bind = schemaitem.bind |