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`EntityAdapter` in NgRx is a helper that simplifies working with **collections of objects** (for example, a list of users, products, or posts).

Instead of writing a pile of logic by hand for:

- adding,
- updating,
- removing items by `id`,

you use ready-made methods.

### How it works:

Say you have a list of users.

Instead of storing them as an array, `EntityAdapter` converts this into a structure:

```ts
{
  ids: [1, 2, 3],
  entities: {
    1: { id: 1, name: 'Maria' },
    2: { id: 2, name: 'Oleh' },
    3: { id: 3, name: 'Alice' }
  }
}
```

This makes updates fast and convenient.

### What EntityAdapter provides:

- `addOne(entity)`
- `addMany([...])`
- `updateOne({ id, changes })`
- `removeOne(id)`
- `setAll([...])`

All these methods immediately update `ids` and `entities` correctly.

### Example:

```ts
const adapter = createEntityAdapter<User>();

const initialState = adapter.getInitialState({
  loaded: false
});

const reducer = createReducer(
  initialState,
  on(loadUsersSuccess, (state, { users }) => adapter.setAll(users, { ...state, loaded: true }))
);
```

**Conclusion:**
`EntityAdapter` is a tool that turns collections into a convenient structure and provides a set of methods for managing them.
You write less by hand and make fewer mistakes.

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