On Thursday, January 3, 2013 8:05:29 PM UTC+1, Michael Bayer wrote:
>
>
> On Jan 3, 2013, at 12:51 PM, [email protected] <javascript:> wrote:
>
> Hi,
>
> I have one set of tables and I want to automate the insertion of the
> company_id in queries at certain tables. So I need to define in the models
> which tables are effected, no worries there, but where do I need to
> implement the query manipulation? The SQLAlchemy object is shared between
> different requests (as the configuration remains te same). But the session
> is different, as the company_id differs between sessions.
>
> Where and how do I implement the query manipulation?!
>
>
> its not clear what usage pattern you're looking for here. Lets start
> with the obvious, putting "company_id" in a query:
>
>
> session.query(SomeObject).filter(SomeObject.company_id == 5)
>
> easy enough.
>
> Now what exactly do you want it to look like?
>
> Like,
>
> session_one.query(SomeClassOne) -> automatically put company_id = 8
> session_two.query(SomeClassTwo) -> automatically put company_id
> = 15
>
> ?
>
> if I'm given "session_one" and "SomeClassOne", what is the "company_id"
> for that ?
>
> There's a pattern for auto-querying of a certain column at
> http://www.sqlalchemy.org/trac/wiki/UsageRecipes/PreFilteredQuery . But
> this doesn't get into how to determine where the custom criterion would
> come from.
>
>
Thanks for your guided questions and the example pattern. Indeed the basic
query would be
session.query(SomeObject).filter(SomeObject.loginname.like("example")).filter(SomeObject.company_id
== SomeHTTPSessionGlobal.company_id)
As this query is extension is used many times in my codebase (due to the
multi-tentancy nature of the concept) I want to automate this. I have
implemented and new Query-class;
session = sessionmaker(bind=engine, query_cls=MyQuery)
In this MyQuery two things need to happen; A) check whether the queried table
has the certain company_id field and B) automatically implement the additional
filter to add the SomeHTTPSessionGlobal.company_id (which is based on the
sub-domain)
=> Is by altering the get(), __ite__ and from_self() functions enough to effect
all queries?
=> How to get the adjusted table and detect whether an company_id field exists?
In such that when the SomeObject has an field company_id, it automatically
applies an additional filter. So that my query in the code may be;
session.query(SomeObject).filter(SomeObject.loginname.like("example"))
Thanks
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