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 receive 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 in the articles written in this section; they help to solve common problems.