ManyToMany relationship with intermediate model and admin list display with each realtion with value as diferent column

[Ignacio Soto]

Hey guys

i have an issue, i don know if it really can be done.

im using django 1.3

i have a model producto(product) and Tienda(store)

and a product could be in one or more stores, so i created a many to many relationship but y have a stock in each store, so i use the intermediary model ProductStore.

i want to create this, in the admin , product's  list display, i want to show each manutomany relationship as a diferent column qith the stock as the value.

as shown in the picture, this i could do by add a method in the model getTienda1 and return the stock and do it for each store, but i want it to be created dinamically because the user could create a new store and it will not be there.

so this is my cuestion: can i do that?

(Sorry for my bad english)

[Tomas Neme]

> as shown in the picture, this i could do by add a method in the model
> getTienda1 and return the stock and do it for each store, but i want it to
> be created dinamically because the user could create a new store and it will
> not be there.
>
> so this is my cuestion: can i do that?

Interesting question. You COULD try the following:

in the ProductAdmin ModelAdmin's class' __init__ you can define list_display like

from store.models import Tienda
for store in Tienda.objects.all():
    self.list_display.append('stock_tienda_{id}'.format(id=store.id))

this would give you the list of existing stores at server init time.
and then you could define your Product model's __getattr__ method something like this:

def __getattr__(self, attr):
     base = 'stock_tienda_'
     if attr[:len(base)] == base:
         return Product.objects.filter(tienda=Tienda.objects.get(id=attr[len(base):]))
     return super(Product, self).__getattr__(self, attr)

this should make the ModelAdmin's hack work

finally, you need a way to add new columns for newly created stores, so maybe a post_save signal on Tienda objects

@receiver(post_save, sender=Tienda)
def add_to_product_list_display(sender, instance, new, **kwargs):
      if new:
          # I don't know how to get the ModelAdmin's instance for a given class,
          #  but it must be something in django.contrib.admin.site
          product_admin.list_display.append('stock_tienda_{id}'.format(id=instance.id))

you probably need another listener before .delete of stores, and I'm not certain the __getattr__ hack will work, but this sounds interesting.

Please try on those lines, and let me know if this worked, I'm most interested

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[Ignacio Soto]

ok, it looks very nice i will try and let you know.. thanks

2012/7/24 Tomas Neme <lacry...@gmail.com>

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Ignacio Soto Reveco
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