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.
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)
print CreateTable(
Table('foo', MetaData(),
Column('data', String('max')),
Column('data2', String(50))
)
)
print CreateTable(
Table('foo', MetaData(),
Column('data', String('max')),
Column('data2', String(50))
)
).compile(dialect=mssql.dialect())
>
> Thanks
>
> Ed
>
> Index: lib/sqlalchemy/dialects/mssql/base.py
> ===================================================================
> --- lib/sqlalchemy/dialects/mssql/base.py (revision 6897)
> +++ lib/sqlalchemy/dialects/mssql/base.py (working copy)
> @@ -668,7 +668,9 @@
> else:
> collation = None
>
> - if type_.length:
> + if type_.length=='max':
> + spec = spec + "(%s)" % type_.length
> + elif type_.length:
> spec = spec + "(%d)" % type_.length
>
> return ' '.join([c for c in (spec, collation)
> Index: lib/sqlalchemy/sql/compiler.py
> ===================================================================
> --- lib/sqlalchemy/sql/compiler.py (revision 6897)
> +++ lib/sqlalchemy/sql/compiler.py (working copy)
> @@ -1237,9 +1237,13 @@
> return "NCLOB"
>
> def visit_VARCHAR(self, type_):
> + if type_.length == 'max':
> + type_.length = None
> return "VARCHAR" + (type_.length and "(%d)" % type_.length or
> "")
>
> def visit_NVARCHAR(self, type_):
> + if type_.length == 'max':
> + type_.length = None
> return "NVARCHAR" + (type_.length and "(%d)" % type_.length or
> "")
>
> def visit_BLOB(self, type_):
>
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