Django: Get() Returned More Than One Items -- It Returned 3

I got an error MultipleObjectsReturned: get() returned more than one items -- it returned 3!. I want edit and update an existing record in the database. Below are my model, views

Solution 1:

just go through the django documentation https://docs.djangoproject.com/en/2.0/topics/http/shortcuts/#get-object-or-404

it internally calls get() https://docs.djangoproject.com/en/2.0/ref/models/querysets/#django.db.models.query.QuerySet.get

it will raise MultipleObjectsReturned if more than one object was found.

you need to either pass primary_key or any other fild to get_object_or_404 like:get_object_or_404(MyModel, pk=1)

or you can use filter() if you want multiple records.

Solution 2:

As other answers have pointed out, you need to filter the queryset in get_object_or_404 so that it only returns a single object. However the next question is how do you know which object to fetch?

The usual approach for edit pages is to include the primary key or a unique slug in the url pattern:

path('edit_purchase/<int:pk>/', views.edit_purchase, name='edit_purchase'),

You then need to update the view to accept the new argument, and use it in get_object_or_404.

def edit_purchase(request, pk):
    entry =get_object_or_404(Purchases, pk=pk)

Finally, you need to include the argument when you reverse the URL, e.g.

{% url 'geo_gas:edit_purchase' entry.pk %}

Solution 3:

You need to provide arguments to get_object_or_404 not just model.

Take a look at source code of get_object_or_404:

defget_object_or_404(klass, *args, **kwargs):
    """
    Uses get() to return an object, or raises a Http404 exception if the object
    does not exist.

    klass may be a Model, Manager, or QuerySet object. All other passed
    arguments and keyword arguments are used in the get() query.

    Note: Like with get(), an MultipleObjectsReturned will be raised if more than one
    object is found.
    """

Also consider naming your Purchases model as Purchase to follow single naming convention.

Solution 4:

fixed purchase function for editing - correction

def edit_purchase(request):

        ""Edit an existing purchase record."""
        entry = get_object_or_404(Purchases, pk=1)
        #entry = Purchases.objects.filter(pk='date_added')#purchase = entry.purchaseif request.method != 'POST':
            # Initial request; pre-fill form with the current entry
            form = PurchasesForm(instance=entry)
        else:
            # POST data submitted; process data.
            form = PurchasesForm(instance=entry, data=request.POST)
            if form.is_valid():
                form.save()
                return HttpResponseRedirect(reverse('geo_gas:purchases'))

        context = {'entry': entry, 'form': form}
        return render(request, 'geo_gas/edit_purchase.html', context)