Learning the fundamentals of GraphQL
GraphQL APIs contain three important root types – query, mutation, and subscription. These are all defined in the GraphQL schema using special SDL syntax.
GraphQL provides a single endpoint that returns the JSON response based on the request, which can be a query, a mutation, or a subscription.
First, let’s understand queries.
Exploring the Query type
The Query type is used for reading operations that fetch information from the server. A single Query type can contain many queries. Let’s write a query using SDL to retrieve the logged-in user, as shown in the following GraphQL schema:
type Query { me: LogginInUser
# You can add other queries here
}
type LoggedInUser {
id: ID
accessToken: String
refreshToken: String
username: String
}
Here, you have done two things:
