Introduction to Graph QL
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The document provides an introduction to GraphQL, highlighting its creation by Facebook, its advantages over REST, and its growing community. It explains GraphQL as a query language for APIs that allows clients to fetch exactly the data they need through a single endpoint, and outlines its type system and CRUD operations. Additionally, it addresses the potential challenges of transitioning from REST to GraphQL, including learning curves and setup requirements.
![For internal use only
Data Under fetching
{
"userName" : "moredee", "firstName" :
"Deepak",
"lastName" : "More",
"isActive" : "true",
"email" : "deepak.more@db.com",
"contactNumber" : "9420390095",
….
}
{
"userName" : "moredee", "firstName" :
"Deepak",
"lastName" : "More",
“Address” : [
…
]
}
{
“id" : “123",
“address Line" : “Nagras Road",
“address Line 1" : “Aundh",
“city" : “Pune",
“State" : “Maharashtra",
“PinCode" : “411007",
….
}
URL – /user/10
URL – /address/123](https://image.slidesharecdn.com/introductiontographqlautosaved16818-191204193512/85/Introduction-to-Graph-QL-13-320.jpg)
![For internal use only
Schema Basics
GraphQL has its own type system that’s used to define the schema of an API.
The syntax for writing schemas is called Schema Definition Language (SDL).
The ! following the type means that this field is required.
type User {
name: String!
contactNo: Int!
posts: [Post!]
}
type Post{
name: String!
author: User!
}
User Post
1 N](https://image.slidesharecdn.com/introductiontographqlautosaved16818-191204193512/85/Introduction-to-Graph-QL-17-320.jpg)
![For internal use only
Validation / Error Handling GraphQL
Error status :
{
"data": null,
"errors": [
{
"message": "Cannot query field ‘names' on type ‘Book'. Did you mean ‘name'? (line 52,
column 5):n namen ^",
"locations": [
{
"line": 52,
"column": 5
}
]
}
]
}
query {
searchbook(name: “java") {
names
author {
firstname
lastName
}
}](https://image.slidesharecdn.com/introductiontographqlautosaved16818-191204193512/85/Introduction-to-Graph-QL-23-320.jpg)
Introduction to Graph QL
- 1. For internal use only Introduction to GraphQL
- 2. For internal use only Rest – REST in peace LonglivetoGraphQL Hello GraphQL Reviews from Developers ++
- 3. For internal use only Index History What is GraphQL Introduction Rapidly Growing community Alternative to Rest CRUD in GraphQL
- 4. For internal use only History Invented by Facebook Presented publically at React JS Conference in 2015 and made open source Specification stable version – 2018 Find releases - https://graphql.github.io/graphql-spec/ 2012 Development Started 2015 Open Sourced 2016 2017 2018 2019 Evolving specification
- 5. For internal use only What is GraphQL • GraphQL is a query language for APIs and a runtime for fulfilling those queries with your existing data. • GraphQL provides a complete and understandable description of the data in your API, gives clients the power to ask for exactly what they need and nothing more, makes it easier to evolve APIs over time, and enables powerful developer tools. • GraphQL is not a database, it’s a specification
- 6. For internal use only Introduction Provides an efficient, powerful and flexible approach to developing web APIs Enables declarative data fetching Exposes Single endpoint and responds to queries Alternative to REST Services Graph QL is not only for React Developers It can be used with any programming language and framework
- 7. For internal use only A Rapidly growing Community Find more Users - https://graphql.org/users/
- 8. For internal use only What we need • User • Users Posts • Follower (likes) • Commenters
- 9. For internal use only Data Fetching with REST
- 10. For internal use only Data Fetching with GraphQL
- 11. For internal use only Single Endpoint vs Multiple Endpoints Img Reference - https://blog.apollographql.com/graphql-vs-rest-5d425123e34b
- 12. For internal use only Data Over fetching { "userName" : "moredee", "firstName" : "Deepak", "lastName" : "More", "isActive" : "true", "email" : "[email protected]", "contactNumber" : "9420390095", "city" : "Pune” …. } { "userName" : "moredee", "firstName" : "Deepak", "lastName" : "More", } URL – /get/user/10
- 13. For internal use only Data Under fetching { "userName" : "moredee", "firstName" : "Deepak", "lastName" : "More", "isActive" : "true", "email" : "[email protected]", "contactNumber" : "9420390095", …. } { "userName" : "moredee", "firstName" : "Deepak", "lastName" : "More", “Address” : [ … ] } { “id" : “123", “address Line" : “Nagras Road", “address Line 1" : “Aundh", “city" : “Pune", “State" : “Maharashtra", “PinCode" : “411007", …. } URL – /user/10 URL – /address/123
- 14. For internal use only Problem with Advanced requests Rest Api - GET /users/1/friends/1/dogs/1?include=user.name,dog.age GraphQL : query { user(id: 1) { friends { dogs { name } } } }
- 15. For internal use only GraphQL vs REST Comparison Points REST GraphQL EndPoints Multiple Single Fetching data Over fetching and Under fetching Fetch Exact Data Dependency on Endpoint Highly Dependent Not Dependent Production Iteration at Frontend Slower Faster Advanced Request Complex Easy
- 16. For internal use only GraphQL Type System Object Types Interfaces Unions Enumerations Fields List Scaler Types Int Float String Boolean Id (serialized in String)
- 17. For internal use only Schema Basics GraphQL has its own type system that’s used to define the schema of an API. The syntax for writing schemas is called Schema Definition Language (SDL). The ! following the type means that this field is required. type User { name: String! contactNo: Int! posts: [Post!] } type Post{ name: String! author: User! } User Post 1 N
- 18. For internal use only CRUD in GraphQL Graph QL Operations Query - use to read a data Mutation - use to write a data Subscriptions - use to listen for data query { search(id: “123456"){ name posts(last: 1) { title } followers { name } } } Mutation { createUser(name: “Deepak“, age: 28){ id } Subscription { onCreate { name age } }
- 19. For internal use only Self Explanatory query{ book(isbn: “SEBT125") { name author { firstname lastName } } Give me the book with isbn=“SEBT125" Give me the book's name Give me the book's author Give me the author's first name Give me the author’s last name
- 20. For internal use only GraphQL Execution Engine Parse Query from Client Validate Schema Return JSON response Executes resolvers for each field
- 21. For internal use only Server Architecture /graphql (Single endpoint) Dao Layer Business Layer Schema Validation Layer Resolvers (Query, Mutation, Subscription) /graphiql (Editor)
- 22. For internal use only 2 Ways to access GraphQL App GraphQL Editor Application – (Windows) https://electronjs.org/apps/graphiql GraphiQL Server Utility Localhost:8080/graphiql
- 23. For internal use only Validation / Error Handling GraphQL Error status : { "data": null, "errors": [ { "message": "Cannot query field ‘names' on type ‘Book'. Did you mean ‘name'? (line 52, column 5):n namen ^", "locations": [ { "line": 52, "column": 5 } ] } ] } query { searchbook(name: “java") { names author { firstname lastName } }
- 24. For internal use only Demo Used Technologies Node Js, Express, MySQL Database (Server Configuration) ReactJS, Websockets, Apollo Client (Using React Render Props) Demo Covers : Book Creation Subscription
- 25. For internal use only How to do Server-side Caching Server-side caching still is a challenge with GraphQL.
- 26. For internal use only 1) Should I stop Using Rest API Now? 2) Should I migrate current application to GraphQL? Answer is No
- 27. For internal use only Authentication and Authorization in GraphQL Authentication can be done by using Oauth To implement authorization, it is recommended to delegate any data access logic to the business logic layer and not handle it directly in the GraphQL implementation.
- 28. For internal use only Disadvantages You need to learn how to set up GraphQL. The ecosystem is still rapidly evolving so you have to keep up. You need to define the schema beforehand => extra work before you get results You need to have a GraphQL endpoint on your server => new libraries that you don't know yet The server needs to do more processing to parse the query and verify the parameters
- 29. For internal use only Resources Find libraries for technologies – https://graphql.org/code/ Editor - https://lucasconstantino.github.io/graphiql-online/
- 30. For internal use only References https://graphql.org/learn/ https://www.howtographql.com/ https://blog.apollographql.com/graphql-vs-rest-5d425123e34b
- 31. For internal use only Demo Used Technologies Spring Boot, h2 Database (Server Configuration) ReactJS, Apollo Client (Using React Render Props) Demo Covers : Book Creation Book Deletion Books List
Editor's Notes
- #6: I simple language, Graph QL is actually a specification around http for how you get and receive resources from a server.
- #9: GraphQL helps where your client needs a flexible response format to avoid extra queries and/or massive data transformation with the overhead of keeping them in sync. Using a GraphQL server makes it very easy for a client side developer to change the response format without any change on the backend.
- #12: Single Endpoint is serving your purpose.
- #13: Over-fetching is fetching too much data, meaning there is data in the response you don't use.
- #14: Under-fetching is not having enough data with a call to an endpoint, forcing you to call a second endpoint.
- #15: GraphQL helps where your client needs a flexible response format to avoid extra queries and/or massive data transformation with the overhead of keeping them in sync. Using a GraphQL server makes it very easy for a client side developer to change the response format without any change on the backend.
- #20: With GraphQL, you can describe the required data in a more natural way. It can speed up development, because in application structures like top-down rendering in React, the required data is more similar to your component structure.
- #26: One common concern with GraphQL, especially when comparing it to REST, are the difficulties to maintain server-side cache. With REST, it’s easy to cache the data for each endpoint, since it’s sure that the structure of the data will not change. With GraphQL on the other hand, it’s not clear what a client will request next, so putting a caching layer right behind the API doesn’t make a lot of sense.
- #27: Should I abandon the REST API and always should use Graph QL. And is there like no usage of REST API now. I would say No There is no mandate like migrate your application to GraphQL right now. There is no such high an immediate need that you should implement graph QL Millions of Millions Queries in Single Day. – GraphQL REST Service wiil be there