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https://github.com/timdeschryver/ngrx-immer

Immer wrappers around NgRx methods createReducer, on, and ComponentStore
https://github.com/timdeschryver/ngrx-immer

angular immer ngrx state

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Immer wrappers around NgRx methods createReducer, on, and ComponentStore

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README

        

# ngrx-immer

> Immer wrappers around NgRx methods to simplify mutating state

* [ngrx-immer](#ngrx-immer)
* [Installation](#installation)
* [Functions](#functions)
* [`createImmerReducer` (@ngrx/store)](#createimmerreducer-ngrxstore)
* [`immerOn` (@ngrx/store)](#immeron-ngrxstore)
* [`ImmerComponentStore` (@ngrx/component-store)](#immercomponentstore-ngrxcomponent-store)
* [`immerPatchState` (@ngrx/signals)](#immerpatchstate-ngrxsignals)
* [`immerReducer`](#immerreducer)
* [FAQ](#faq)
* [Resources](#resources)

## Installation

```bash
npm install ngrx-immer
```

> Do not forget to install immer

## Functions

### `createImmerReducer` (@ngrx/store)

Creates an NgRx reducer, but allows you to mutate state without having to use to spread operator.

- Use it when you want to go Immer all the way
- Caveat, you have to return the state with each `on` method

```ts
import { createImmerReducer } from 'ngrx-immer/store';

const todoReducer = createImmerReducer(
{ todos: [] },
on(newTodo, (state, action) => {
state.todos.push({ text: action.todo, completed: false });
return state;
}),
on(completeTodo, (state, action) => {
state.todos[action.index].completed = true;
return state;
}),
);
```

### `immerOn` (@ngrx/store)

Creates an NgRx reducer, but allows you to mutate state without having to use to spread operator.

- Use it when you want to go sprinkle a little bit of Immer for more complex cases

```ts
import { immerOn } from 'ngrx-immer/store';

const todoReducer = createReducer(
{ todos: [] },
on(newTodo, (state, action) => {
return {
...state,
todos: [...state.todos, action.todo],
};
}),
immerOn(completeTodo, (state, action) => {
state.todos[action.index].completed = true;
}),
);
```

### `ImmerComponentStore` (@ngrx/component-store)

Wraps Immer around the Component Store `updater` and `setState` methods.

```ts
import { ImmerComponentStore } from 'ngrx-immer/component-store';

@Injectable()
export class MoviesStore extends ImmerComponentStore {
constructor() {
super({ movies: [] });
}

readonly addMovie = this.updater((state, movie: Movie) => {
state.movies.push(movie);
});
}
```

### `immerPatchState` (@ngrx/signals)

> [!IMPORTANT]
> Because `@ngrx/signals` is in developer preview, the `immerPatchState` function is also in developer preview. It is ready to try, but may change before becoming stable.

Provides an Immer-version of the `patchState` function from the `@ngrx/signals` package. In addition to partial state objects and updaters that update the state immutably, it accepts updater functions that update the state in a mutable manner. Similar to `patchState`, the `immerPatchState` function can be used to update the state of both SignalStore and SignalState.

```ts
const UserStore = signalStore(
withState({
user: { firstName: 'Konrad', lastName: 'Schultz' },
address: { city: 'Vienna', zip: '1010' },
}),
withMethods((store) => ({
setLastName(lastName: string): void {
immerPatchState(store, (state) => {
state.user.lastName = lastName;
});
},
setCity(city: string): void {
immerPatchState(store, (state) => {
state.address.city = city;
});
},
}))
);
```

Please note, that the updater function can only mutate a change without returning it or return an immutable
state without mutable change.

This one is going to throw a runtime error:

```ts
// will throw because of both returning and mutable change
immerPatchState(userStore, (state) => {
state.name.lastname = 'Sanders'; // mutable change
return state; // returning state
});
```

### `immerReducer`

Inspired by [Alex Okrushko](https://twitter.com/alexokrushko), `immerReducer` is a reducer method that uses the Immer `produce` method.
This method is used by all the methods in `ngrx-immer` provides.

## FAQ

- See the Immer docs, [Update patterns](https://immerjs.github.io/immer/docs/update-patterns), on how to mutate state

## Resources

- [Immer docs](https://immerjs.github.io/immer/)
- [NgRx docs](https://ngrx.io/docs/)