The query type in GraphQL represents a read-only view of all of our entities and ways to retrieve them. A query type is required for every GraphQL server.

type Query {
  books: [Book!]!
  author(id: Int!): Author
}

Clients can query one or more fields through the query type.

query {
  books {
    title
    author
  }
  author(id: 1) {
    name
  }
}

Queries are expected to be side-effect free and are therefore parallelized by the execution engine.

Usage

A query type can be defined like the following.

public class Query
{
    public Book GetBook()
    {
        return new Book { Title  = "C# in depth", Author = "Jon Skeet" };
    }
}

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services
            .AddGraphQLServer()
            .AddQueryType<Query>();
    }
}

⚠️ Note: Only one query type can be registered using AddQueryType(). If we want to split up our query type into multiple classes, we can do so using type extensions.

Learn more about extending types

A query type is just a regular object type, so we can do everything we could do with an object type with the query type (this applies to all root types).