How to do a not equal in Django queryset

In Django, filtering data from the database is typically done through QuerySet methods provided by Django’s ORM (Object Relational Mapping). When you need to filter records where a certain field is not equal to a specific value, Django offers an elegant way to handle this using the exclude() method or the __ne field lookup. This article will guide you through how to perform a "not equal" operation in Django queries.

Sample Django Model

[
    {"id": 1, "name": "Laptop", "category": "Electronics", "in_stock": True, "order__status": "Delivered"},
    {"id": 2, "name": "Shirt", "category": "Clothing", "in_stock": False, "order__status": "Processing"},
    {"id": 3, "name": "Book", "category": "Stationery", "in_stock": True, "order__status": "Cancelled"},
    {"id": 4, "name": "Mug", "category": "Kitchen", "in_stock": True, "order__status": "Delivered"},
    {"id": 5, "name": "Phone", "category": "Electronics", "in_stock": False, "order__status": "Processing"},
    {"id": 6, "name": "Pencil", "category": "Stationery", "in_stock": True, "order__status": "Delivered"}
]

Using the exclude() Method

Django's exclude() method allows you to filter out records that meet a specific condition. It is essentially the opposite of the filter() method, which returns objects that match the given criteria. To retrieve records where a field is not equal to a specific value, you can exclude the value you want to avoid.

Example 1: Exclude a Specific Value

Suppose you have a model Product and you want to exclude products from the category "Electronics."

from myapp.models import Product

# Query for products where the category is NOT 'Electronics'
products = Product.objects.exclude(category='Electronics')

In this example, the exclude() method returns all products where the category is not equal to "Electronics." Any product with "Electronics" as its category will be omitted from the result set.

Output

[
    {"id": 2, "name": "Shirt", "category": "Clothing", "in_stock": False, "order__status": "Processing"},
    {"id": 3, "name": "Book", "category": "Stationery", "in_stock": True, "order__status": "Cancelled"},
    {"id": 4, "name": "Mug", "category": "Kitchen", "in_stock": True, "order__status": "Delivered"},
    {"id": 6, "name": "Pencil", "category": "Stationery", "in_stock": True, "order__status": "Delivered"}
]

Example 2: Exclude Multiple Values

If you need to filter out multiple values, you can chain multiple exclude() methods or use Q objects.

from myapp.models import Product
from django.db.models import Q

# Exclude products where category is 'Electronics' or 'Clothing'
products = Product.objects.exclude(Q(category='Electronics') | Q(category='Clothing'))

Here, products belonging to either "Electronics" or "Clothing" are excluded from the result.

Output

[
    {"id": 3, "name": "Book", "category": "Stationery", "in_stock": True, "order__status": "Cancelled"},
    {"id": 4, "name": "Mug", "category": "Kitchen", "in_stock": True, "order__status": "Delivered"},
    {"id": 6, "name": "Pencil", "category": "Stationery", "in_stock": True, "order__status": "Delivered"}
]

Combining exclude() with Other Filters

Unlike SQL, Django does not natively support a __ne (not equal) field lookup. The exclude() method is the recommended way to handle "not equal" conditions. However, if you need to negate other types of conditions (e.g., "not in" or "not like"), the exclude() method can still be used.

You can combine exclude() with filter() to build complex queries where you need to filter on multiple conditions and also exclude certain records.

Example: Filtering and Excluding Together

Imagine you want to get products that are in stock but not in the category "Electronics."

from myapp.models import Product

# Filter products that are in stock, but not in the 'Electronics' category
products = Product.objects.filter(in_stock=True).exclude(category='Electronics')

In this case, the filter() method ensures only products that are in stock are returned, while the exclude() method filters out products in the "Electronics" category.

Output

[
    {"id": 3, "name": "Book", "category": "Stationery", "in_stock": True, "order__status": "Cancelled"},
    {"id": 4, "name": "Mug", "category": "Kitchen", "in_stock": True, "order__status": "Delivered"},
    {"id": 6, "name": "Pencil", "category": "Stationery", "in_stock": True, "order__status": "Delivered"}
]

Using exclude() with Related Models

You can also use the exclude() method to filter out records based on related fields. Consider an example where you have a Customer model related to an Order model via a foreign key, and you want to exclude customers who have placed orders with a specific status.

from myapp.models import Customer

# Exclude customers who have orders with the status 'Cancelled'
customers = Customer.objects.exclude(order__status='Cancelled')

Here, customers with at least one "Cancelled" order are excluded from the results.

Output

[
    {"id": 1, "name": "Laptop", "category": "Electronics", "in_stock": True, "order__status": "Delivered"},
    {"id": 2, "name": "Shirt", "category": "Clothing", "in_stock": False, "order__status": "Processing"},
    {"id": 3, "name": "Book", "category": "Stationery", "in_stock": True, "order__status": "Cancelled"},
    {"id": 4, "name": "Mug", "category": "Kitchen", "in_stock": True, "order__status": "Delivered"},
    {"id": 5, "name": "Phone", "category": "Electronics", "in_stock": False, "order__status": "Processing"},
    {"id": 6, "name": "Pencil", "category": "Stationery", "in_stock": True, "order__status": "Delivered"}
]

Conclusion

In Django, filtering records where a field is not equal to a certain value is easily done using the exclude() method. While Django does not have a direct __ne lookup, the exclude() method allows you to negate any condition with simplicity and efficiency. Whether you're dealing with simple filters or more complex queries involving related models, exclude() provides a powerful tool for customizing your database queries.