Introduction to GraphQL

Learn about GraphQL, how it works, and how to use it. Looking for documentation on how to build a GraphQL service? There are libraries to help you implement GraphQL in many different languages. For an in-depth learning experience with practical tutorials, see the available training courses.

GraphQL is a query language for your API, and a server-side runtime for executing queries using a type system you define for your data. GraphQL isn't tied to any specific database or storage engine and is instead backed by your existing code and data.

A GraphQL service is created by defining types and fields on those types, then providing functions for each field on each type. For example, a GraphQL service that tells you who the logged in user is (me) as well as that user's name might look like this:

type Query {
  me: User
}

type User {
  id: ID
  name: String
}

Along with functions for each field on each type:

function Query_me(request) {
  return request.auth.user
}

function User_name(user) {
  return user.getName()
}

After a GraphQL service is running (typically at a URL on a web service), it can receive GraphQL queries to validate and execute. The service first checks a query to ensure it only refers to the types and fields defined, and then runs the provided functions to produce a result.

For example, the query:

{
  me {
    name
  }
}

Could produce the following JSON result:

{
  "me": {
    "name": "Luke Skywalker"
  }
}

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