On 7 Apr 2010, at 21:14, Michael Bayer wrote:
Ed Singleton wrote:
I wanted to be able to use Varchar('max') for some columns in
SQLAlchemy (for legacy reasons we have both Varchar(max) and Text
columns). I also needed it to create a new database correctly (from
the same schema) in MS SQL and Sqlite, whilst retaining the same
errors as before for all strings passed in as length arguments to a
column type.
The patch included below does this, and seems to working fine for me.
Is it possible for this to be added to SA? If not, is there a way I
can achieve this without using a patched version of SA?
I'm not crazy about 'max' outside of the MS-SQL dialect if its an MS-
SQL
specific keyword.
That's entirely understandable. I'm getting quite annoyed with their
desire to do things differently to everyone else.
An approach that will get you everything you want right now is:
from sqlalchemy import *
from sqlalchemy.ext.compiler import compiles
from sqlalchemy.schema import CreateTable
from sqlalchemy.dialects import mssql
@compiles(String)
def compile_varchar(element, compiler, **kw):
if element.length == 'max':
return "VARCHAR"
else:
return compiler.visit_VARCHAR(element, **kw)
@compiles(String, 'mssql')
def compile_varchar(element, compiler, **kw):
if element.length == 'max':
return "VARCHAR('max')"
else:
return compiler.visit_VARCHAR(element, **kw)
This seems a perfectly satisfactory solution.
I really need to get sqlalchemy.ext.compiler into my headspace. You
seem to answer all my questions lately with "Use the compiler, Luke".
Thanks (again)
Ed
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