On Wed, Jan 8, 2014 at 3:37 PM, Mark S <dbs...@gmail.com> wrote:
> Hi
>
> I can successfully use pagination with the following -
>
> mydata=Article.query.filter(Article.author_id==User.id).filter(User.id==g.user.id).paginate(page,
> POSTS_PER_PAGE, False)
>
> However, I need to fetch columns from multiple tables. In that case how can
> I modify the code above in order to use pagination?
>
> Here is what I need to do -
>
> mydata = db.session.query("id","title","Author").from_statement("\
> SELECT
> a.id,a.title,u.author \
> FROM article a, user u\
> where a.user_id=u.id \
> and u.id=:userid")\
>
> .params(userid=g.user.id).all()
>
> However, with this , pagination does not work and I get an error -
> AttributeError: 'Query' object has no attribute 'paginate'
>
>
> Can you please help?
>
There are a couple of options. One would be to configure your
"db.session" object to use the Flask-sqlalchemy query class, rather
than the default SQLAlchemy one. The Session class constructor has a
query_cls parameter for this purpose - you'd want to pass
flask_sqlalchemy.BaseQuery. I don't use Flask, so I don't know how
your session is currently being configured.
Another option would be to use the with_entities method of Query to
change the set of columns that are being queried for:
http://docs.sqlalchemy.org/en/rel_0_9/orm/query.html#sqlalchemy.orm.query.Query.with_entities
so you could write something like "Article.query.with_entities('id',
'title', 'Author').from_statement(...)"
But I guess what you are really trying to do is to query Articles, but
only to load certain columns. You might be interested in using
"load_only" instead:
http://docs.sqlalchemy.org/en/rel_0_9/orm/mapper_config.html#load-only-cols
which is part of a bigger topic about deferred column loading:
http://docs.sqlalchemy.org/en/rel_0_9/orm/mapper_config.html#deferred-column-loading
Hope that helps,
Simon
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sqlalchemy+unsubscr...@googlegroups.com.
To post to this group, send email to sqlalchemy@googlegroups.com.
Visit this group at http://groups.google.com/group/sqlalchemy.
For more options, visit https://groups.google.com/groups/opt_out.
