Rules of Thumb pt2

When to create actions?

  • Anytime we want to interact with the store or API

  • No shortcuts

  • Use classes for actions

  • Use enums for action names

  • Export actions types using a union type

  • 3 action approach - request, success, failure

  • Consider Action Creators

Single action that does everything - Anti Pattern

// Single action that does everything
export class UpdateUsers implements Action {
 readonly type = UserActionTypes.UpdateUsers;
 constructor(public payload: { users: User[] }) {}

Sample Action

  • Don’t do it

  • Complicates reducers

  • Easy to mutate store

  • Prefer dictionaries vs arrays (NgRx Entity)

Maximize Selectors

Use Selectors to filter/manipulate data from the store

  • Supports parameters

  • Memoized

  • Release memoization

Service With a Subject

  • Most projects don’t need NgRx

  • Simple pattern

  • Works well with container/presenter

  • Upgradable to NgRx

Service with a subject basics

  • Regular Angular service

  • Private member variable of type BehaviorSubject

  • Public get prop to access stream

  • Service methods update stream

When NOT to use Service with a Subject?

  • Application or feature is complex

  • Want to track state changes

  • Recreate user errors

  • Implement advanced logging

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