GraphQL Guru

Schema

GraphQL Non-Null Types

Non-Null Types

GraphQL non-null types enforce required fields with !.

What Are GraphQL Non-Null Types?

In GraphQL, non-null types are used to ensure that a field, argument, or variable cannot be null. This is indicated by appending an exclamation mark ! to the type name. By using non-null types, you can enforce that a particular field must always be provided with a value, thus preventing potential issues related to null values in your data.

Why Use Non-Null Types?

Non-null types are crucial in scenarios where certain fields are mandatory for the operation of your application. They help to:

  • Reduce the need for null checks in your application code.
  • Ensure data integrity by enforcing required fields in your schema.
  • Improve the reliability of your GraphQL API by avoiding unexpected null values.

Defining Non-Null Types in Schema

To define a non-null type in your GraphQL schema, simply append an exclamation mark ! to the type you want to make non-null. Here's an example:

In this example, the id and name fields are marked as non-null, meaning they must always contain a value. The email field, however, is nullable and can be null.

Non-Null Types in Operation Arguments

Non-null types are not limited to fields alone. They can also be used in operation arguments to enforce that certain inputs are mandatory. Consider the following example:

Here, the createUser mutation requires both name and email arguments to be non-null, ensuring that these values must be provided when the mutation is executed.

Handling Non-Null Types in Client Requests

When making requests to a GraphQL API, clients must adhere to the non-null constraints defined in the schema. Failing to provide a value for a non-null field or argument will result in a validation error. Therefore, it's important to ensure that your client-side code handles these requirements correctly.

This mutation request will succeed because it provides values for both non-null arguments name and email. If either of these were omitted, the request would fail with an error.

GraphQL Schema

Previous
Lists
Next
Schema Definition