Thank you Anthony. Your answers are always very clear. Archibald
On 2 nov, 22:15, Anthony <abasta...@gmail.com> wrote: > On Wednesday, November 2, 2011 4:46:45 PM UTC-4, Archibald Linx wrote: > > > Dear Web2py users, > > > I have a few questions about validators, especially : when are they > > necessary ? > > > For example, if I have like in chapter 3 ( > >http://www.web2py.com/book/default/chapter/03?search=image_id) : > > > db.define_table('comment', > > Field('image_id', db.image)) > > > Is "db.comment.image_id.requires = IS_IN_DB(db, db.image.id)" or even > > "db.comment.image_id.requires = IS_IN_DB(db, db.image.id, '% > > (title)s')" redundant ? I am asking because one could think this is > > already declared in the table definition. > > Yes, those validators are necessary. Specifying Field('image_id', db.image) > doesn't prevent inserting a value that isn't actually a db.image reference > (it just tells the model that the field is intended to be a reference > field, which among other things, causes the representation of the field to > be the format attribute of the referenced table), so you need to enforce it > with validators. Also, the IS_IN_DB validator results in the form widget > displaying a dropdown. > > Note, strictly speaking, it isn't necessary to explicitly specify the > IS_IN_DB validator for a reference field because it is assigned by default, > though you may want to specify it if you need to set options other than the > defaults, which are IS_IN_DB(db,'<table>.id',db.<table>._format). > > Anthony
