First, I am not debugging the code, just browsing it, and found that:
def sqlhtml_validators(field):
"""
Field type validation, using web2py's validators mechanism.
makes sure the content of a field is in line with the declared
fieldtype
"""
field_type, field_length = field.type, field.length
if isinstance(field_type, SQLCustomType):
if hasattr(field_type,'validator'):
return field_type.validator
else:
field_type = field_type.type
requires=[]
if field_type == 'string':
# ....
elif field._db and field_type[:9] == 'reference' and \
field_type.find('.')<0 and \
field_type[10:] in field._db.tables:
referenced = field._db[field_type[10:]]
if hasattr(referenced,'_format') and referenced._format:
def f(r,id):
row=r[id]
if not row:
return id
else:
return r._format % row
field.represent = lambda id, r=referenced, f=f: f(r,id)
requires = validators.IS_IN_DB(field._db,referenced.id,
referenced._format)
return requires
I am also not aware of web2py internals, so I have no idea how the
code above could figure out which columns to load for using the
format, so absolutely no idea. Also could not find anything that shwos
me any optimization which fields are loaded when using format in
define_table...
I hope there is an object cache, so I will not have to fetch objects
one-by-one. Querying them once again should not harm...
On Fri, Jan 8, 2010 at 14:01, mdipierro <mdipie...@cs.depaul.edu> wrote:
> What do you want to do with it? Are you planning to fecth one record
> at the time for every record in all possible references? I would not
> recommend it.
>
> I am not saying no to your proposal of a represent function. I am just
> saying we need to think it over more.
>
> In the end what you want (and makes sense) is a simpler syntax for
> merging format with virtualfields. I think if we do this we must do it
> well and it is not a minor change.
>
> Massimo
>
> On Jan 8, 6:42 am, "KONTRA, Gergely" <pihent...@gmail.com> wrote:
>> Well, then let the function accepts not a row, but an id, which is the
>> pk of the row.
>>
>> On Fri, Jan 8, 2010 at 13:01, mdipierro <mdipie...@cs.depaul.edu> wrote:
>> > 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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>>
>>
>
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