web2py form with list:reference not working with {{=form}}

Question

Using web2py, I am having trouble submitting (?) a form based on a table using list:reference. I have a table db.game that references to db.game_events in one of its columns called game_event.

The form for db.game is accepted, but when I try to reach the data in the column game_events, that uses list:reference reffering to db.game_events, the column is empty according to the built in web2py grid.

I can see that the information is correctly posted to the database, showing the items in brackets in the supposedly empty column. Since I am using the built in web2py grid, I am assuming the collection of the rows is correct and that the problem lies elsewhere.

If I use the "Add record to database"-titled button in the web2py console (the black button with the plus-sign), and use the form there, the game_events column shows the items.

So; if I try to use {{=form}} in the application, the game_event-column is treated as empty, but if I use the built in "Add record to database", the information is there. The question is simply; why can I not use {{=form}} for db.game anywhere in the application, when the built in form works fine? I have tried to simply use {{=form}} and not custom.

To make it even more confusing, if I edit any game in db.game in the web2py grid, and press "submit" without altering any information, the game_event column in the rows for db.game correctly show the game_events.

I have been stuck on this forever, I really would appreciate help! Thanks.

Code in db.py

db.define_table(
    'game',
    Field('name', label='Tävlingsnamn'),
    Field('status', requires=IS_IN_SET(define_game_status),default='started'),
    Field('registration_start_date', 'date', requires = IS_DATE(format=('%Y-%m-%d')),label=T('Registrering öppnar')),
    Field('registration_end_date', 'date', requires = IS_DATE(format=('%Y-%m-%d')),label=T('Registrering stänger')),
    Field('start_date','date',requires = IS_DATE(format=('%Y-%m-%d')),label=T('Start date')),
    Field('end_date','date',requires = IS_DATE(format=('%Y-%m-%d')),label=T('End date')),
    Field('tracs_available','integer', requires=IS_IN_SET(define_track_amount), widget=div_radio_widget, label=T('Tracks')),
    Field('tracs_available_sprint','integer', requires=IS_IN_SET(define_track_amount), widget=div_radio_widget, label=T('Sprint tracks')),
    Field('game_type', requires=IS_IN_SET(define_game_type),default='Inactive', label=T('Type of event')),
    Field('description','text',label=T('Description')),
    Field('game_event',type='list:reference db.game_events', label='Tävlingsgren'),
    format = '%(name)s')

db.game.game_event.requires=IS_IN_DB(db,'game_events.id','%(name)s',multiple=True)

db.define_table(
    'event_class',
    Field('name'),
    format = '%(name)s')

db.define_table(
    'game_events',
    Field('name'),
    Field('class_name', requires=IS_IN_DB(db,db.event_class.name,'%(name)s')),
    Field('event_type', requires=IS_IN_SET(define_game_event_types)),
    format ='%(id)s')

Code in the controller registration.py

#FORM GAMES
def create_game():
    #Form handling  
    #FORM
    form = SQLFORM(db.game)
    request.vars._formname = 'game'

    form.custom.widget.name.update(_placeholder="ex Skelleftespelen") 

    #Registration of results in view            
    if form.accepts(request.vars, session, formname='game'):    
            print("accepted")
            response.flash = 'Tävlingen har skapats!'
            #game_rows = db(db.game).select(orderby=db.game.name)
            return dict(form=form)    

    elif form.errors:
        response.flash = 'form has errors' 

    return dict(form=form)

Code in the view create_game.html

  <div class="game_name">
            <h4>
                Tävling
            </h4> 
                {{=form.custom.begin}}
                Namn <div>{{=form.custom.widget.name}}</div>      
                Första anmälningsdag <div>{{=form.custom.widget.registration_start_date}}</div>
                Sista anmälningsdag <div>{{=form.custom.widget.registration_end_date}}</div>
                Första tävlingsdag <div>{{=form.custom.widget.start_date}}</div>
                Sista tävlingsdag <div>{{=form.custom.widget.end_date}}</div>
                Sort <div>{{=form.custom.widget.game_type}}</div>
                Sort <div>{{=form.custom.widget.status}}</div>         
                Löparbanor <div>{{=form.custom.widget.tracs_available}}</div>
                Sprintbanor <div>{{=form.custom.widget.tracs_available_sprint}}</div> 
                Beskrivning och/eller information <div>{{=form.custom.widget.description}}</div>          
      Grenar</br></br>
      <p style="background:#FFE066; font-weight:bold;">
          Notera: för att välja grenar måste samtliga önskade grenar att markeras med ctrl + musklick.
        </p>
                <div>{{=form.custom.widget.game_event}}</div>               
                <span id="submit_result">{{=form.custom.submit}}</span>
                {{=form.custom.end}}
    </div> 

Answer 1

When you define a reference or list:reference field, if you don't specify the requires attribute within the call to Field(), you will get a default requires attribute (i.e., validator) as well as a default represent attribute that controls how the field is displayed in forms and the grid. However, in order to get the default requires and represent attributes, you must define the referenced table before defining the referencing field (otherwise, the referencing field does not have enough information to create the validator and represent attributes, both of which incorporate the format attribute of the referenced table).

So, just move the definition of db.game_events so it comes before the definition of db.game. Also, in that case, there is no need to explicitly set the value of db.game.game_event.requires, as it will be assigned a default value exactly the same as the one you are assigning.

More generally, if you don't like the default representation of a field's values in forms/grids, you can always set the field's represent attribute to control the display.

As an aside, prefer type='list:reference game_events' over type='list:reference db.game_events' (the latter works but is not officially supported).