Hi,
I was trying to define a subclass of CheckConstraint to match a column
(whose name is given) to a regexp.
class CodenameConstraint(CheckConstraint):
"""Check that the column uses a limited alphabet."""
def __init__(self, column_name):
column = ColumnClause(column_name)
super(CodenameConstraint, self).__init__(
column.op("~")("^[A-Za-z0-9_-]+$"))
This ends up failing because the regexp is stored using a bind parameter
but then lost somewhere along the way. Here is a traceback:
File "/home/luca/Development/cms/cms/db/init.py", line 34, in init_db
metadata.create_all()
File "/usr/lib/python2.7/site-packages/sqlalchemy/sql/schema.py", line
3860, in create_all
tables=tables)
File "/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line
1920, in _run_visitor
conn._run_visitor(visitorcallable, element, **kwargs)
File "/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line
1529, in _run_visitor
**kwargs).traverse_single(element)
File "/usr/lib/python2.7/site-packages/sqlalchemy/sql/visitors.py", line
121, in traverse_single
return meth(obj, **kw)
File "/usr/lib/python2.7/site-packages/sqlalchemy/sql/ddl.py", line 733,
in visit_metadata
_is_metadata_operation=True)
File "/usr/lib/python2.7/site-packages/sqlalchemy/sql/visitors.py", line
121, in traverse_single
return meth(obj, **kw)
File "/usr/lib/python2.7/site-packages/sqlalchemy/sql/ddl.py", line 767,
in visit_table
include_foreign_key_constraints=include_foreign_key_constraints
File "/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line
945, in execute
return meth(self, multiparams, params)
File "/usr/lib/python2.7/site-packages/sqlalchemy/sql/ddl.py", line 68,
in _execute_on_connection
return connection._execute_ddl(self, multiparams, params)
File "/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line
1002, in _execute_ddl
compiled
File "/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line
1189, in _execute_context
context)
File "/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line
1393, in _handle_dbapi_exception
exc_info
File "/usr/lib/python2.7/site-packages/sqlalchemy/util/compat.py", line
203, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb, cause=cause)
File "/usr/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line
1182, in _execute_context
context)
File "/usr/lib/python2.7/site-packages/sqlalchemy/engine/default.py",
line 470, in do_execute
cursor.execute(statement, parameters)
sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) syntax error
at or near ":"
LINE 4: name VARCHAR NOT NULL CHECK (name ~ :name_1),
I am using SQLAlchemy 1.1.6 with PostgreSQL. Am I doing anything wrong or
is this a bug?
Thanks!
PS: I know I can use a string, like "%s ~ '...'" % column_name, but in
other cases the regexps are more complicated and I don't want to worry
about escaping.
PS: I also know that I can add the constraint using __table_args__ at the
end of the class definition, passing the actual Column object, but I prefer
the constraint to be given to the Column constructor to keep it local.
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