Re: Adding filtering API

[Iago Toral Quiroga <itoral igalia com>]

El jue, 20-01-2011 a las 10:14 +0100, Juan A. Suárez Romero escribió:
> On Thu, 2011-01-20 at 08:46 +0000, Iago Toral wrote:
> >  If they are, I would go with a filtering support with the following 
> >  limits:
> >  - Limited filters, filters on random metadata would not be allowed
> > like 
> >  (bitrate = X). Still it should be easy to extend the list of allowed 
> >  filters.
> >  - No support for grouping operations like this: (artist=X AND
> > album=Y) 
> >  OR (date-min=Z AND artist=A).
> >  - No support for operator precedence (plugin developers would not 
> >  ensure certain precedence for operators), or we could just force all
> > the 
> >  operators of one filter to be of the same kind.
> >  - No support for operators other than "=", so no filters like (artist
> > > 
> >  X) or (album != Y)
> > 
> >  Of course, we could be more flexible than this if we think is worth
> > the 
> >  effort, so I would like to hear your thoughts on this matter. For 
> >  example, we can have plugins declare what keys the support for
> > filtering 
> >  and remove the limited filters restriction (Grilo could check the 
> >  filters provided by the users and simply remove the parts that are
> > not 
> >  supported or fail the operation if unsupported keys are used in the 
> >  filter before passing the filter to the plugin).
> > 
> 
> My concert is how plugins declare which kind of filtering are they
> supporting. For instance, they should tell which fields they support for
> filtering. But at the same time, they need to specify if they support
> combinations or not.

Or maybe they can just fail with error "filter type not supported" if
they don't. I think most services that support filtering would support
at least the AND case.

> If we found a way of doing it, then I agree providing a filtering
> search, keeping the restrictions you mentioned (supporting only '='
> operation, and the AND combination).
> 
> By the way, if finally we go with it, I have a proposal to do it,
> something I thought some time ago, and that would make easier for
> clients and plugins to handle the filtered search.

Let's not talk about how we can implement this yet and focus the
discussion on what we want to support :)

Iago