This might be OK if you have a single web app, and it’s deployed at the same time as your backend, but definitely unacceptable if you’re using this API from a native app that the user has to update manually, or if it’s a public API. In the following schema, we have a Restaurant type with a location field that refers to a Location type: type Restaurant When and why you should use it in your schema.How non-null in GraphQL works, and what it does.In this article, we’ll go over two things: By default, every field in GraphQL is nullable, and you can opt in to mark it non-null. A field can either be nullable or non-null, and this tells you whether or not you could receive a null value when you ask for it. But what if a field is simply not available, for example if the record you’re retrieving never got that value assigned, or there was an error fetching a piece of data?Įven GraphQL can’t get you a piece of data that doesn’t exist, but it has the next best thing: a built in concept of nullability.

GraphQL improves on that by having a complete schema of your available data, and giving you back exactly the fields you asked for. In Kotlin by default, the data types are of non-nullable types i.e trying to assign a value as null would cause an error. When you’re working with a REST API, you don’t always know exactly what fields you’re going to get back when you call an endpoint. Like the hole in a donut, what isn’t there can be just as important as what is.

Kotlin null default value