Here is the problem. Perhaps you have a solution.
format is used to represent a record in a reference as a select/
option. Probably you have many of these records and you only want to
fetch columns that are necessary to build the representation.
By using format='%(first_name)s %(last_name)s' web can parse it and
easily figure out that you only need first_name and last_name.
My example above is convoluted but it allows you to create an
arbitrary representation and specify exactly which fields you need.
By using represent you are passing a (lambda) function. How would
web2py determine which columns to fetch? Should it fetch them all? It
could be slow.
Massimo
On Jan 8, 5:13 am, "KONTRA, Gergely" <pihent...@gmail.com> wrote:
> Since the patch is about 2 lines of code, does it make sense to have a
> represent for tables, similar for fields, so that I could write
> something like:
>
> db.post.represent = lambda row: row['title'], which means the same as
> using format='%(title)s' on define_table?
> thx
> Gergo
>
> On Thu, Jan 7, 2010 at 20:32, mdipierro <mdipie...@cs.depaul.edu> wrote:
> > Now I understand.
>
> > Short answer. It cannot be done in the sense there is no API for it
>
> > Long answer. It can be done this way:
>
> > ### define table post and set the format
> > ### based on a field that does not exist
> > db.define_table('post',
> > Field('title',length=256),
> > Field('body','text',requires=IS_NOT_EMPTY()),
> > Field('author',db.auth_user),
> > format='%(title_short)s',
> > )
>
> > ### define the field as a virtual field computed
> > class ComputedFieldsForPost:
> > def title_short(self):
> > return self.post.title[:40]+'...'
> > db.post.virtualfields.append(ComputedFieldsForPost())
>
> > ### define the referencing table
> > db.define_table('comment',
> > Field('post',db.post,writable=False,readable=False),
> > Field('author',db.auth_user,writable=False,readable=False),
> > Field('body','text',requires=IS_NOT_EMPTY()))
>
> > ### modify an internal of the validator to
> > ### fetch data required to compute the virtual field
> > db.comment.post.requires.fields=['post.id','post.title']
>
> > This kind of ugly but powerful.
>
> > On Jan 7, 12:25 pm, "KONTRA, Gergely" <pihent...@gmail.com> wrote:
> >> Sure.
>
> >> db.py:
>
> >> db.define_table('post',
> >> Field('title',length=256),
> >> Field('body','text',requires=IS_NOT_EMPTY()),
> >> Field('author',db.auth_user),
> >> )
>
> >> db.define_table('comment',
> >> Field('post',db.post,writable=False,readable=False),
> >> Field('author',db.auth_user,writable=False,readable=False),
> >> Field('body','text',requires=IS_NOT_EMPTY()))
>
> >> In the example I provided, in the appadmin of comment, auth_user is
> >> displayed as a dropdown. I would like to do that for comment.post
> >> also.
>
> >> The format option make it possible to hack up some fields of the
> >> database, but it is not so flexible to display for eg. computed values
> >> of the post table.
>
> >> thanks in advance
> >> Gergo
> >> On Thu, Jan 7, 2010 at 16:35, mdipierro <mdipie...@cs.depaul.edu> wrote:
> >> > Hi Gergo,
>
> >> > appadmin has nothing to do with t2 and t2 was deprecated long ago.
>
> >> > I guess you can still define db.post.represent but I am not sure what
> >> > do you want to do with it. What behavior do you expect? Can you
> >> > provide a concrete example?
>
> >> > On Jan 7, 9:31 am, "KONTRA, Gergely" <pihent...@gmail.com> wrote:
> >> >> Yes, AFAIK appadmin is a T2 thing.
>
> >> >> So, I wonder how can one rewrite the line below using
> >> >> db.post.represent (still that is more flexible)
>
> >> >> db.define_table('post',
> >> >> Field('title',length=256),
> >> >> Field('body','text',requires=IS_NOT_EMPTY()),
> >> >> Field('author',db.auth_user),
> >> >> format='%(title)s')
>
> >> >> db.post.represent = ?
>
> >> >> thanks
> >> >> Gergo
>
>
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