Hi Samuel,
Thanks a ton for this detailed suggestion. I was almost certain, the
solution i was trying is not the optimal. Now its very clear. Thanks very
very much. You made my weekend. I will be all busy backing up my database
and implementing what you suggested.
Initially after reading your reply, i wondered, how can database handle it
if there is no linking table. Especially, bulk of my data goes in using
perl uploader. I started this project from designing the database & loading
data first then adopting models from it. But, after reading one of your
links, (Behind the scenes, Django creates an intermediary join table to
represent the many-to-many relationship.) i am clear how it works.
I might even try to use .through to adopt exisiting linking tables. But,
will try NOT doing that as its a simple manytomany relationship as you
observed.
Once again, THANKs very much for educating me,
Gowthaman
On Sat, Mar 24, 2012 at 3:36 AM, Sam Lai <samuel....@gmail.com> wrote:
> On 24 March 2012 09:29, gowtham <ragowtha...@gmail.com> wrote:
> > Template tag filters like this (made one for each field in the library
> > object) helps me to get what i wanted.... But, that seems too silly to
> do...
> >
> > in template
> > <td>{{ reslibdic|hash2libcode:res.result_id }}</td>
> >
>
> I had the same thought as Reinout did, but after your clarification I
> realised you want to get something out of reslibdic by using another
> variable as the key. AFAIK, there is no in-built way of doing this.
>
> However, it is worth taking a step back and having a look at what
> you're trying to do.
>
> "I have two models (Library and Result) linked by a third linking
> model (libraryresult (has id, library_id and result_id fields FKeyed
> to respective tables). A many to many relationship."
>
> By the sounds of things, you have actually defined a third model,
> libraryresult, that links the Library and Result models together. That
> third model is unnecessary (unless you have other attributes to store
> with the link, which you don't seem to have - if you do, see
>
> https://docs.djangoproject.com/en/1.4/topics/db/models/#intermediary-manytomany
> ).
>
> If you simply define a ManyToManyField on the Result model pointing to
> the Library model, e.g.
>
> class Result(models.Model):
> # ...
> libraries = models.ManyToManyField(Library)
>
> ... then you can get all the related libraries for a particular result
> by simply doing -
>
> r = Result.objects.get(pk=1)
> print r.libraries.all()
>
> You can do the same in the template. There is no need to build the
> reslibdic object.
>
> See
> https://docs.djangoproject.com/en/1.4/topics/db/models/#many-to-many-relationships
> for help defining the model, and
>
> https://docs.djangoproject.com/en/1.4/topics/db/queries/#many-to-many-relationships
> for help querying the related objects.
>
> > in template tag file:
> >
> > def hash2libcode(h,key):
> > if key in h:
> > return h[key].librarycode
> > else:
> > return None
> >
> > register.filter(hash2libcode)
> >
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>
--
Gowthaman
Bioinformatics Systems Programmer.
SBRI, 307 West lake Ave N Suite 500
Seattle, WA. 98109-5219
Phone : LAB 206-256-7188 (direct).
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