Only first referenced Field in "Row"

[niphlod]

see web2py/web2py#1177

[gi0baro]

@niphlod This is gonna be hard.

Is not a fortuity I've rewritten the one-to-many and many-to-many relations in weppy:

class User(Model):
    has_many({'owned_todos': 'Todo.owner'}, {'assigned_todos': 'Todo.assignee'})

class Todo(Model):
    belongs_to({'owner': 'User'})
    refers_to({'assignee': 'User'})

in pyDAL how should we know which of the multiple reference we should inject? Possibilities are:

• obeying user to define a reverse relation (as I do in weppy)
• use the solution proposed in Only first referenced Field in "Row" web2py#1177 of using a list of reverse relations. I personally don't like this approach since you have the "reverse relation attribute" that change type depending on the definitions of the table (sometimes is a Set, sometimes a list of sets). But is a possible way.
• something else? (can't think about a different approach right now)

Would hear @mdipierro on this for his thoughts. Also, what do you thing @niphlod ?

[niphlod]

in retrospect, every "reference" field should definitely generate a referenced Set. it makes no sense creating just the first one.

[ilvalle]

The example is odd however supporting it should not be difficult by introducing an array of referenced sets as proposed in the example by @misl6 while maintaining the current approach when there is only one referenced set (without the containing array).
By doing this pydal is still backward compatible, otherwise it's possible to always place an array even if there is only one referenced set.