# 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**

{% hint style="danger" %}
Single action that does everything - Anti Pattern
{% endhint %}

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

## Sample Action

{% embed url="<https://stackblitz.com/edit/advanced-ngrx-0-rulesofthumb?file=src%2Fapp%2Fusers%2Factions%2Fuser.actions.ts&view=editor>" %}

## Related/Nested Data

* **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**

{% embed url="<https://stackblitz.com/edit/tour-of-heroes-service-with-subject?file=src%2Fapp%2Fcore%2Fhero.service.ts&view=editor>" %}

## When NOT to use Service with a Subject?

* **Application or feature is complex**
* **Want to track state changes**
* **Recreate user errors**
* **Implement advanced logging**

{% hint style="info" %}
Refactor Tour of Heroes to use Service with a subject [https://stackblitz.com/github/jessesanders/tour-of-heroes/tree/**s**ervice-with-subject](https://stackblitz.com/github/jessesanders/tour-of-heroes/tree/container-presenter)
{% endhint %}