[Grok-dev] Multiple models inside container

[Martijn Faassen]

On 03/17/2011 01:32 PM, Lumir Jasiok wrote:
[snip]
> But now I want to add Employee class, that will be similar to Store
> class. Inside Employee AddForm I want to save inside Awis context. After
> that I will not be able to recognize which ID belongs to Store object
> and Which to Employee object. How can I correctly save Store objects and
> Employees objects inside Awis container and be able to recognize them.
> Using dictionaries - self.context.stores and self.context.employees? -
> but how can I access those dictionaries from TAL?
>
> Or am I completely wrong and there is better way to do it?

There are different solutions.

You could create two containers and make them @grok.traversible and 
store them in the Awis object, one for Employee and one for Store.  You 
might need to set up the sub-containers in an event handler for the add 
event to make it set up right; not sure it works in the __init__(). This 
would, I think, be the simplest approach and makes sure your objects are 
in different containers altogether. Container making explicit subclasses 
for the subcontainers, such as EmployeeContainer and StoreContainer, so 
that you can create specific views for them and such later.

Alternatively you could indeed store everything withint Awis. One way to 
distinguish the two is to simply use Python's isinstance() and loop 
through the things in the container in some helper method:

def get_employees(self):
   employees = []
   for value in self.values():
       if isinstance(value, Employee):
            employees.append(value)
   return employees

This won't be very fast if you have *many* employees or stores, though, 
as it'll have to loop through them each time. Instead, you could 
consider using the catalog. You can then index these things in the 
catalog, and look them up quickly in the index. You'd probably have to 
set up a "model_type"  (or whatever name you pick) attribute on the 
Store and Employee classes that you can index first:

class Employee(...):
    model_type = 'employee'

setting up the catalog is something you need to google for.

Note that you can still use the catalog even if you spread things into 
different containers as sketched out above.

Regards,

Martijn