On Tue, Sep 29, 2009 at 9:11 PM, Eric Lemoine
<eric.lemo...@camptocamp.com> wrote:
> On Tue, Sep 29, 2009 at 9:04 PM, Michael Bayer <mike...@zzzcomputing.com>
> wrote:
>>
>> Eric Lemoine wrote:
>>>
>>> Hi
>>>
>>> Here's my case: I have
>>>
>>> - my own TypeEngine class, MyTypeEngine
>>> - a Table with a Column using MyTypeEngine:
>>> table = Table("tablename", metadata,
>>> Column("columname", MyTypeEngine()),
>>> autoload=True, autoload_with=engine
>>> )
>>> - a class:
>>> class MyClass(object):
>>> pass
>>> - and a mapping:
>>> mapper(MyClass, table)
>>>
>>> Pretty standard. Now, instead of queries like this:
>>>
>>> SELECT columnname, ... FROM tablename
>>>
>>> I'd like queries like this:
>>>
>>> SELECT somefunc(columnname),... FROM tablename
>>>
>>> I thought I could get that by overriding my column's ColumnProperty
>>> with something like that:
>>>
>>> mapper(MyClass, table, properties={
>>> "columname": column_property(
>>> sql.func.somefunc(table.c.columname).label("columnname")
>>> )
>>> })
>>>
>>> but it doesn't work as I'd like because it seems that my TypeEngine is
>>> no longer involved after querying my table - the function returned by
>>> my TypeEngine's "result_process" method doesn't seem to be called.
>>>
>>> Is this expected? Do I have solutions to that problem?
>>
>> somefunc() needs to specify the return type using type_=MyType, unless its
>> a known "generic" function that knows to pass through the type of the
>> first argument as that of the result (such as lower(), for example).
>
> it's a postgis function. How do I specify the return type using
> type_=MyType? Sorry i didn't follow you on that one.
sql.func.somefunc(col, type_=MyType) I guess
i'll try that, thanks again
>
> thanks
>
>
>>
>> >>
>>
>
>
>
> --
> Eric Lemoine
>
> Camptocamp France SAS
> Savoie Technolac, BP 352
> 73377 Le Bourget du Lac, Cedex
>
> Tel : 00 33 4 79 44 44 96
> Mail : eric.lemo...@camptocamp.com
> http://www.camptocamp.com
>
--
Eric Lemoine
Camptocamp France SAS
Savoie Technolac, BP 352
73377 Le Bourget du Lac, Cedex
Tel : 00 33 4 79 44 44 96
Mail : eric.lemo...@camptocamp.com
http://www.camptocamp.com
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To post to this group, send email to sqlalchemy@googlegroups.com
To unsubscribe from this group, send email to
sqlalchemy+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sqlalchemy?hl=en
-~----------~----~----~----~------~----~------~--~---
