GraphQL

GraphQL is a query language for API.
Server-side runtime for executing queries using a type system you define for data.

 

 

Describe API with a type system

type Query {  
	category : Fruit
} 

type Fruit {  
    name: String
}

 

 

Along with functions for each field on each type

// Provide data for the `me` field on the `Query` type

function Query_fruit (query, args, context, info) { 
	return context.request.auth.user
}

// Provide data for the `name` field on the `Fruit` type

function Fruit_name(fruit, args, context, info) {  
	return context.db.getFruitName(fruit.id)
}

 

 

Json Result

{  
	 "data": {    
		 "fruit": {     
		  "name": "apple"    
		  }  
	  }
}

 

 

For example

type Fruit {  
	type: String  
	quentity: Int
	name: String @deprecated(reason: "Use `fullName`.")
}

• The @deprecated directive has a nullable

 

 

---

 

 

Operation

Request
{
  hero {
    name     # add additional fields here!
  }
}

Response
{
  "data": {
    "hero": {
      "name": "apple"
    }
  }
}

 

 

Object types and fields

type Fruit {
	name: String!
	appearsIn: [Categories!]!
}

• Fruit is a GraphQL Object type, it’s type with some fields
• name and appearsIn are fields on the Fruit type
• String! means that the field is a Non-Null type
• [Categories!] represents an List type

 

 

Arguments

type airplane {
	id: ID!
	name: String!
	length(unit: lengthUnit = METER) : Float
}

• All arguments are named.
• the length field has one defined argument called unit.
• When an argument is optional, we can define a default value.
• If the unit argument is not passed, then it will be set to METER by default.
• GraphQL supports Enum type, Scalar type and Interface types

 

 

Interface usage example

interface Marvel {
	id: ID!
	name: String!
	friends: [Character]
	appearsIn: [Episode]!
}

type Mankind implements Marvel{
	id: ID!
	name: String!
	friends: [Character]
	appearsIn: [Episode]!
}

type Elf implements Marvel{
	id: ID!
	name: String!
	friends: [Character]
	appearsIn: [Episode]!
	skills: [SkillSet] 
}