Hi,
I'd like to come up with a string column type that prevents empty
values, or a function that returns a string column which prevents empty
values.
I've tried two approaches, both of which failed:
class NotEmptyString(String, SchemaType):
def _set_table(self, column, table):
table.append_constraint(CheckConstraint(column != ''))
The above works, but results in two check constraints for each
NotEmptyString on each table, why is that?
def not_empty_string(size, **kw):
col = Column(String(size), nullable=False, **kw)
cons = CheckConstraint(col!='')
cons._set_parent_with_dispatch(col)
return col
So, I tried this to get around the two-check-constraints problem, but
here the issue is that I don't have the column name when I need to make
the constraint, the above barfs when creating the table:
ProgrammingError: (ProgrammingError) syntax error at or near ":"
LINE 3: id VARCHAR(10) NOT NULL CHECK (table.col != :param_1),
What should I have been doing here and what am I doing wrong?
In the meantime, I'll just use table-level check constraints, but I'd
like to make this DRY and I don't want to risk forgetting the constraint
for a column...
cheers,
Chris
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