On Sunday, December 11, 2011 1:53:11 PM UTC-5, tsvim wrote:
>
> db.define_table('table_settings',
> Field('name','string'),
> Field('default_value','string'))
>
> db.define_table('data',
>
> Field('parent_table',db.table_settings,writable=False,readable=False),
> Field('datetime','datetime',default=request.now),
> Field('title','string'),
> Field('value','string'))
>
> db.data.value.default = db.table_settings['parent_table'].default_value
> db.table_settings.default_value.requires = IS_IN_SET(['a','b'])
>
It looks like you want the default value of db.data.value to be dependent
on the particular parent_table selected. Obviously, this cannot be
determined until after the parent_table has been selected. What do you want
the user experience to be? Are you creating a form where the user will
select a parent_table (i.e., one of the values stored in table_settings)?
Upon selection, do you want the 'value' field to then be dynamically
populated with the default_value from table_settings? If so, you'll need to
set up an Ajax call on the client side. Another simpler alternative is
using a computed field:
Field('value', compute=lambda r:
db.table_settings[r.parent_table].default_value)
Note, by default, computed fields are not displayed in SQLFORMs. If you
want the field to be displayed, you'll have to explicitly list the fields
you want shown in the form. If the user leaves that field blank, the value
will be computed as above -- otherwise, the user's submitted value will be
inserted. Note, in this case, the user will not see any default value
pre-populated in the field -- it will simply be blank and filled in on the
server side after submission if no value has been entered.
See http://web2py.com/book/default/chapter/06#Computed-Fields.
Anthony
