Graph Query Language, API that allows client to define the structure of the data they want actually

GraphQL = Restful

Graphql follows all 6 constrant of RestAPI. It takes approach of being query-centric because it is structured to functions similarly to a database query language like SQL

Find URL where hosted & Submit authorized req. that contains query parameter as body of POST req. to access GraphQL API.

like :-

query{
  users{
    username
    id
    email
  }
}
                     REQ.

{
"data":{
"users":{
"username":hapi_hacker
"id":1111
"email":[email protected]

}
}
}                    RES.

In Graphql Request, the body of the POST req. is what the provider process

In Below Example, GraphQL req. & res. depicting a req. to check store’s inventory of graphic card

POST /graphql HTTP/1.1
HOST: graphql-shop.com
Authorization: Bearer ab4dtok3n

{query1️⃣{
  inventory2️⃣{(item:"Graphics Card"){
name
fields3️⃣{
price
quantity
}
}                    REQ.
}
}

HTTP/1.1 200 OK
Content-type: application/json
Server: GraphqlServer

{"data":{
"inventory":{
"name":"Graphics Card",
"fields":4️⃣[
"price":"999.99"
"quantity":25
}
]
}
}
}                     RES.

unlike GraphQL consumers REST API needs to filter out the data if consumer only need to a specific value but

• GraphQL API let client request specific fields from a resource
• GraphQL Also Uses HTTP, But it depends on a single entry point (URL) using the POST method

As you See In the Above Example :-

1️⃣, which is equivalent to GET req. & used to obtain info. from API

2️⃣, is also known as root query type

3️⃣, similar to key/ value pair in REST. The main difference is that we can specify the specif field we are looking for

4️⃣, Instead of getting item ID, item name, and other superfluous info. , The Query resolved with only field we needed

GraphQL uses 3 operations within the POST request to interact with GraphQL APIs: query, Mutation & Subscription.

• Query: operation to retrieve data (read)
• Mutation: is an operation used to submit and write data (create, update and delete).
• Subscription: is an operation used to send data (read) when an event occurs. Subscription is way for Graphql client to listen to live updates from the server.

How do you know the structure or info. need to query the GraphQL API?

GraphQL uses Schemas, a collection of the data that can be queries with the given service. Having Access to the GraphQL schemas similar to having access to a REST API collection.

A Graphql schema will provide you with the information you’ll need in order to query the API.

Data Interchange in API

API Uses several formats to facilitate the exchange of data.

We will talk about 3 Common Format : JSON, XML, YAML

JSON

Javascript Object Notation is primary data interchange format widely used in APIs

JSON Represents objects as key/value pairs separated by commas,

with the pair of curly brackets

{
 "firstname":"Jason",
 "lastName":"haddix",
 "platform":"twitter",
 "Followers":124400,
 "footboller":false,
 "hobbies":"gaming",
 "isbughunter":true,
 "experience":["bug hunting","Security Consultant","Penetration tester"]
}

Json doesn’t allow inline comment, any sort of comment-like communication must take place as a key/value pair like “comment” : “This is a comment”