How to filter objects by values of foreign objects in Django admin

[9dev...@gmail.com]

There are tables Product and Transaction. In Product admin there is a field that shows how many transactions have been created with this product.

Now, I want to filter the period of time in which these transactions were created. For example, there was 30 transactions in the last week, but 100 in the last month.

class Transaction(models.Model):
    created = models.DateTimeField()
    product = models.ForeignKey('Product')

class Product(models.Model):
    name = models.CharField()

    def num_of_trans(self):
        return Transaction.objects.filter(created="""DATE_VALUE_HERE""").filter(product=self.id).count()

I tried to adjust the queryset in a class that extends SimpleListFilter, however I did not manage to make it work.

Another thing I thought of was to add an additional parameter to num_of_trans function, but it seems there is not way to pass this parameter while using the filter.

I would appreciate any tips.

[Shubham Pansari]

Instead of self.id you should use self itself as using self.id will not work.

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[9dev...@gmail.com]

Thanks for pointing it out.

However, my question is about a different issue.

[Lachlan Musicman]

For Range of dates:

https://docs.djangoproject.com/en/dev/ref/models/querysets/#range

for "greater than" or "less than" dates (and what that means), look at
the filter docs:

On 7 July 2014 22:12, <9dev...@gmail.com> wrote:
> Thanks for pointing it out.
>
> However, my question is about a different issue.
>

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> https://groups.google.com/d/msgid/django-users/fa5bbf2c-c699-4ef2-8b4e-85b14206d7f6%40googlegroups.com.

>
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[Lachlan Musicman]

Gah, sorry. Fat thumbed the send button

https://docs.djangoproject.com/en/dev/ref/models/querysets/#django.db.models.query.QuerySet.filter

[9dev...@gmail.com]

Thank you, but I think you misunderstood.

I do not want to filter Product objects. I want to filter Transaction objects.

Please, take a look at provided example.

[Tom Evans]

On Mon, Jul 7, 2014 at 11:47 AM, <9dev...@gmail.com> wrote:
> There are tables Product and Transaction. In Product admin there is a field
> that shows how many transactions have been created with this product.
>
> Now, I want to filter the period of time in which these transactions were
> created. For example, there was 30 transactions in the last week, but 100 in
> the last month.
>
> class Transaction(models.Model):
> created = models.DateTimeField()
> product = models.ForeignKey('Product')
>
> class Product(models.Model):
> name = models.CharField()
>

def num_of_trans(self, start_date=None, end_date=None):
qs = self.transaction_set.all()
if start_date:
qs = qs.filter(created__gt=start_date)
if end_date:
qs = qs.filter(created__lt=end_date)
return qs


Does that suffice?

Cheers

Tom

[9dev...@gmail.com]

No, it does not. I cannot pass any parameters to this function, because it is being invoked automatically by the admin.

class MyAdmin(admin.ModelAdmin):
    list_display = ['num_of_trans']

How can I pass any arguments to it?

Please, read my question carefully.

[Derek]

There is not really enough information about your use case (which is maybe why people seem to be misunderstanding your question).  

Its not really clear to me what you mean by "pass a parameter", as you have not given any indication where or how this parameter needs to be set.  

One way I have used to "subset" model lists in the admin is to use proxy models with model managers.  You could define a filter in a new model manager that automatically filters transactions, for example, from the last 7 days.  The proxy model (for example, LastWeekTransaction) can use this model manager to always show a list of the most recent Transactions.

If you actually want to run interactive queries, with users entering in their own date ranges, then you'll need to move beyond the admin app (e.g. by creating a new custome 'query' app), as its purpose is essentially for CRUD, and not for reporting.