Introduction to GraphQL

Learn about GraphQL, how it works, and how to use it in this series of articles. 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, visit the How to GraphQL fullstack tutorial website. We have also partnered with edX to create a free online course, Exploring GraphQL: A Query Language for APIs.

GraphQL is a query language for your API, and a server-side runtime for executing queries by 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 us who the logged in user is (me) as well as that user's name might look something 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();
}

Once a GraphQL service is running (typically at a URL on a web service), it can be sent GraphQL queries to validate and execute. A received query is first checked to ensure it only refers to the types and fields defined, then runs the provided functions to produce a result.

For example the query:

{
  me {
    name
  }
}

Could produce the JSON result:

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

Learn more about GraphQL—the query language, type system, how the GraphQL service works, as well as best practices for using GraphQL to solve common problems—in the articles written in this section.