GraphQL query parsing and validation?

The main aim of this article is to show how a GraphQL query is parsed and validated before execution. Here, I assume the reader knows about what is GraphQL?; how to compose GraphQL schema?; what is GraphQL query? and what are resolvers, mutations and subscriptions?


How does GraphQL work?

GraphQL is a recently proposed, and increasingly adopted framework for providing a new type of data access interface on the web. The framework includes a graph query language that enables app developers to run queries against server API that traverse a graph of application objects and fetch exactly the right amount and format of data in a single request.