How to Check if an Object is in a ManyToManyField in Django

In this article, we show how to check if an object is in a ManyToManyField in Django.

A ManyToManyField in Django is a field that allows multiple objects to be stored. This is useful and applicable for things such as shopping carts, where a user can buy multiple products.

At times, you may want to check if an object is already in the ManyToManyField.

This can be done rather easily in Django.

We will now show how to do this below in our code.

Just to give you reference, this is the following model in the models.py file.

# models.py file class ShoppingCart(models.Model): user= models.OneToOneField(User) products= models.ManyToManyField(Product, blank=True)

So in the models.py file, above, we have a model, ShoppingCart, that contains 2 fields, with the products row being a ManyToManyField.

Now how do we check if a certain product is already in the ManyToManyField?

We show this in the following code in the views.py file.

# views.py file from .models import ShoppingCart from products.models import Product def checkproduct(request, id): currentproduct= Product.objects.get(id=id) shoppingcartuser= ShoppingCart.objects.get(user= request.user) items= shoppingcartuser.products.all() if currentproduct in items: #do this if item is in cart else: #do this if item is not in cart

So in this code, we have to import the model, ShoppingCart, because this is the model that contains the ManyToManyField we are trying to check against.

So each ShoppingCart contains a user. We select the user (the row) of data we want to deal with and get this row. We can then retrieve all of the items from the ManyToManyField, products, from this row.

We retrieve all of the objects from the ManyToManyField, products, using the line, items= shoppingcartuser.products.all()

We then can check if the current product selected is in the shopping cart using an if statement with the Python in keyword.

If the current product is in the ManyToManyField, we can execute a certain block of code. If the current product is not in the ManyToManyField, we can execute a certain block of code.

And this is how we can check if an object is in a ManyToManyField in Django.

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