Implementing GraphQL mutations

Most services need to modify data as well as query it. GraphQL calls these mutations. A mutation has three related components:

• The mutation itself, which defines the change that will be made to the graph. It should be named using a verb, a noun, and use camel casing, for example, addProduct.
• The input is the input for a mutation, and it should have the same name as the mutation with a suffix of Input, for example, AddProductInput. Although there is only one input, it is an object graph so can be as complex as you need.
• The payload is the returned document for a mutation, and it should have the same name as the mutation with a suffix of Payload, for example, AddProductPayload. Although there is only one payload, it is an object graph so can be as complex as you need.

Let’s define mutations for adding, updating, and deleting products:

1. In the Northwind.GraphQL project/folder, add a class file named Mutation...