NestJS

In recent years, many Javascript projects quickly improve developer productivity at building front applications (Angular, React, Vue, etc. ). But what about back applications in Javascript ? Well, there’s a decent choice of very good NodeJs-based libraries and frameworks such as Express, Hapi, Sails, Meteor, etc. However, most of them miss one important thing: clear architectural guidelines. Nest tries to fill this gap ( and actually does well ) and provides you additional up-to-date and desirable server-side features such as Injection Dependency, Microservices, Websocket, Caching, MVC, GraphQL, CRQS, OpenAPI, etc.

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1. Nest
2. hello! I am Karl Devooght You can find me at @karl.devooght I’m a frontend freelance developer And a lot of fancy role names ! 2
3. 1. The motivation 3
4. A (very) brief history of js backend . 4 Node.js Express.js Hapi.js 27 May 2009 2010 2013
5. that ‘s not my architecture 5
6. that ‘s my architecture 6
7. NEST in a word . 7 A backend framework inspired by a frontend framework
8. NEST in a word . 8 An higher level of abstraction based on Express or Fastify
9. NEST in a word . 9 Write in pure javascript or typescript ( babel )
10. NEST in a word . 10 Come with a lot of tools, techniques & recipes
11. NEST in a second . 11
12. NEST in a (kind of) powerful demo . 12
13. 2. The core 13
14. Module 14 ✘ Container of cohesive code related to a part of the application domain ✘ At least one module => Root Module ✘ Feature Module & Shared Module ✘ Easily turn into micro-service
15. 15 Root Module Heroes Module Muggle Module Wizard Module
16. Controller . 16 ✘ Handling incoming request and returning response ✘ Massive use of decorators Routing, Request Params / Body, Headers, etc. ✘ Deal with asynchronicity ✘ One controller for all requests ( by default )
17. Provider . 17 ✘ Something that can inject dependencies ( IoC ) ✘ Every Nest entity has a provider ✘ A class with @Injectable ✘ SOLID compliant
18. Custom Provider . 18 Instance ID / Token String Symbol Class ... Instance Maker useClass useValue useFactory
19. Middleware . 19 ✘ Function called before route handling ✘ Access to request and response ✘ Same meaning than Express middleware ✘ Call next() when intend to move forward
20. Guard . 20 ✘ Determine if a request should be handled by a route handler ✘ Class with a canActivate method ✘ Access to the execution context ( eg. route handler ) ✘ Can enrich execution context with metadata
21. exception . 21 ✘ Handle exceptions across the application ✘ Built-in Http Exception ✘ Exception filter
22. pipe . 22 ✘ Transforms input data to desired output ✘ Can act as data validator using joi or class-validator ✘ Built-in pipes such as ValidatorPipe
23. 3. The techniques 23
24. database . 24 ✘ Object Relational Mapper ✘ Support of a dozen of DB ✘ Repository Design Pattern ✘ Decorators ( @Entity ) TypeORM git push -u origin master
25. database . 25 ✘ CRUD-based generated ✘ Custom Repository ✘ Just need to inject Repository git push -u origin master
26. database . 26 ✘ Multi-database support ✘ Access to connection object ✘ Access to entity manager object Misc git push -u origin master
27. Configuration . 27 “ Store config in the environment -- Twelve Factor App
28. Configuration . 28 Dotenv git push -u origin master ✘ Loads environment variable from env. file ✘ Use of parser service ✘ Inject anywhere into the app
29. caching . 29 cache-manager git push -u origin master ✘ Cache library for Node JS ✘ Unified API for storage providers ✘ Inject anywhere into the controllers git push -u origin master
30. serialization . 30 class-transformer git push -u origin master ✘ Data manipulation before sending them ✘ Exclude, Transform & Compute properties ✘ ClassSerializerInterceptor by default
31. compression . 31 compression git push -u origin master ✘ JS library for compression ✘ Just an express middleware
32. Security 32 Cors Helmet Csurf Rate-limit
33. Documentation . 33 Compodoc Swagger
34. graphql 34 4.
35. definition A query language for API which allows to formulate requests as data structure 35
36. Pros 36 ✘ Request what you want no more no less ✘ Multiple transports ( HTTP, MQTT, WebSocket ) ✘ “True” Single API for multiple clients ✘ Self-documenting through GraphQL schema
37. Graphql schema 37 Query
38. Graphql schema 38 Mutation
39. Graphql schema 39 Subscription
40. Graphql schema 40 Data structure
41. Graphql query 41 Query
42. Graphql query 42 Mutation
43. How can we do that in Nest ? How can i switch from rest to graphql ? 43
44. First approach . 44 ✘ Install some dependencies ( Appolo Server & @nestjs/graphql ) ✘ Define Graphql schema file ( .graphql file ) ✘ (Option) Generate related typings ( ts-node generate-typings ) ✘ Import and configure a Nest Graph module ✘ Convert controller to graphql resolver
45. First approach . 45 Generate Typings
46. First approach . 46 Graphql Module
47. resolver . 47 controller
48. Nice but… I don’t want to learn a new syntax I don’t want to generate typings Just keep focus on my TS code 48
49. second approach . 49 ✘ Install some dependencies ( Appolo Server & @nestjs/graphql ) ✘ Import and configure a Nest Graph module ✘ Decorate your DTO types with type-graphql decorators ✘ Convert controller to graphql resolver with a bit of further description
50. New resolver . 50 resolver
51. . 51 DTO Class as graphql data type
52. microservices 52 5.
53. Microservices are a software development technique that structures an application as a collection of loosely coupled services 53
54. Define a microservice 54 App MS MS MS MS
55. Define a microservice . 55
56. Define a microservice . 56
57. Define a microservice 57 MS MS MS MS Module A Module B Module C Module D MODULE E MODULE F
58. Communication approach 58 Abstract the communication by using pattern Pattern is just a js object !
59. Communication transports 59 Redis TCP NATS MQTT gRPC
60. Listening messages 60
61. Sending messages 61
62. thanks! Any questions? You can find me at @karl.devooght karl.devooght@gmail.com 62
63. Help Looking for a new freelance opportunity Front-end Development / Leading ( Angular ) 63
64. Voxxed days luxembourg Microfrontend or how to break your frontend in thousand pieces 64