GraphQL

• It's a query language developed by facebook
• Similar to SQL queries
• Typed
• Client specified queries

Schemas

type Author {
  id: ID!
  info: Person
}

type Person {
  name: String!
  age: Int
  gender: String
}

GraphQL Types:

• Float
• Integer
• String
• Boolean
• ID

Interfaces

Abstract types for be implemented by other types

interface Shared {
  id: ID!
  name: String
}

type Dog implements Shared {
  did!
  name: String
  breed: String
}

type Person implements Shared {
  id: ID!
  name: String!
  height: Int
  age: Int
}

Resolvers

Are funcions for provide business logic.

fieldName(obj, args, context, info) { result }

• fieldname: Name of the resolver function which should match the field in the schema
• obj: Contains the result returned by the parent field
• args: Holds the arguments passed into the query
• context: Holds the pre-request state like authentication information that should be considered while resolving the query
• info: Contains information about the execution state of the query and should only be used in advanced cases

ExpressJS Example

Basics:

• Data
• Types
• Resolvers
• Schema

Test the app with this:

query{
  getAuthors{
    info{
      name
      age
    }
  }
}