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Getting Started with GraphQL using Node.js

Validate GraphQL Query

Learn how the GraphQL server validates queries from the client.

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By leveraging the type system, we can determine the validity of any query. The system allows servers and clients to notify developers when they send GraphQL queries without relying on runtime checks.

Can’t spread fragment

A fragment can’t refer to itself since this could cause an unbounded result. Here’s the pizzas query with an invalid GraphQL fragment:

Javascript (babel-node)
query GetPizzas {
  Neapolitan: pizzas(name: "Neapolitan Pizza") {
    ...pizzaFields
  }
  Chicago: pizzas(name: "Chicago Pizza") {
    ...pizzaFields
  }
}
fragment pizzaFields on Pizza {
    ... on Pizza {
     id
     pizza
    }
    ... on ChicagoPizza {
     ...pizzaFields // this is invalid!
    }
}

If we execute the query, we’ll receive ...