Hands-On RESTful Web Services with Go - Second Edition

Mutations and inputs

A REST API has methods such as GET, POST, PUT, and DELETE. The method itself describes the operation of the API call. Does GraphQL have something similar? Yes – mutations. A mutation is a GraphQL client query that updates the state of a resource on the server.

Let's look at an example of a counter API. A counter API allows clients to increment and return the counter value. In REST, this is a POST method call. In GraphQL, we have to define mutations in the client query to create-then-fetch results from the server.

Say the GraphQL schema looks like this:

type Query {  counter: Count}type Count {  id: Int  value: Int}

The client query can fetch the count value for an id:

{  counter(id: "250") {    value  }}

This query fetches the ...