Angular DI Processor Pattern

Transcript

1. Angular | Dependency Injection | Processor Pattern + +

2. @JecelynYeen From Kuala Lumpur, Malaysia • GDE - Web technologies,

   Angular • Software Architect @ Randstad Organizer:

3. • Dependency Injection (DI) • DI in Angular • Processor

   Pattern • DI + Processor Pattern in Angular + +

4. Dependency Injection . What & Why?

5. Weapon is made of material (wood). Ninja needs a weapon

   (nunchakus). We have a ninja.

6. - Single Responsibility - Tightly coupled - Hard to unit

   test

7. Dependency Injection

8. Hookup implementation during bootstrap inject in constructor no need to

   instantiate

9. Replace implementation under the hood

10. Dependency Injection • Unit testable • Reusability • Loosely coupled

    • Dependency Inversion principle

11. DI in Angular

12. service service hook up

13. • UseClass • UseValue • UseFactory • UseExisting + https://offering.solutions/blog/articles/2018/08/17/using-useclass-usefactory-usevalue-

    useexisting-with-treeshakable-providers-in-angular/ https://blog.thoughtram.io/angular/2015/05/18/dependency-injection-in-angular-2.html

14. Dependency Injection is static

15. Dependency Injection is static hook up only once

16. what if our ninja need to switch weapon dynamically https://di-processor.firebaseapp.com/ninja-di

17. what if our ninja need to switch weapon dynamically https://di-processor.firebaseapp.com/ninja-di

    nunchakus, dart, stick, sword

18. Processor Pattern using injection token & multi-provider

19. weapon interface name, draw(), animate() Inject into NinjaComponent as weapon[

    ] injection token processors multi-providers

20. Injection Token + Processor Interface

21. Processor implement the interface

22. Multiple providers with same token one token multiple implementations set

    as multi

23. Inject multiple providers Injection 4 processors get one processor Invoke

    processor functions

24. Production Use Case: Chart Processors

25. - chart type - title / menu - processing logic

    - labels & tooltips Differences - they are all charts - same interface:- - processData() - name, title, etc Similar https://di-processor.firebaseapp.com

26. YYYY-MM what users want to see YYYY-MM-DD what backend returns

    Frontend developer

27. what your chart library wants what you need to do

    • transform data (loop & group it by year month) • sort it • generate chart configuration

28. What you actually do - Chart Processor https://github.com/chybie/di-processor/blob/master/src/app/chart-di/services/chart-new-starter-processor.service.ts private

29. Injection Token + Processor Interface

30. Multiple providers with same token

31. Dashboard Component

32. Other useful scenario • Data table processors • Search processors

    https://stackoverflow.com/questions/48382323/angular-lookup-all- providers-implementing-a-specific-interface/ 48383858#comment83773434_48383858

33. Benefits • Abstraction • Plugins

34. slides: https://speakerdeck.com/chybie/angular-di-processor-pattern demo: https://di-processor.firebaseapp.com code: https://github.com/chybie/di-processor code (inject by service):

    https://stackblitz.com/edit/ninja-weapon- processors?file=src%2Fapp%2Fninja%2Fninja.component.ts twitter: @JecelynYeen + +