# 共享状态

Shared state is the ability to get state from one state container and use its properties in another state container in a read-only manner. While it's not natively supported it can be accomplished.

Let's say you have 2 stores: Animals and Preferences. In your preferences store, which is backed by `localstorage`, you have the sort order for the Animals. You need to get the state from the preferences in order to be able to sort your animals. This is achievable with `selectSnapshot`.

```typescript
@State<PreferencesStateModel>({
  name: 'preferences',
  defaults: {
    sort: [{ prop: 'name', dir: 'asc' }]
  }
})
@Injectable()
export class PreferencesState {
  @Selector()
  static getSort(state: PreferencesStateModel) {
    return state.sort;
  }
}

@State<AnimalStateModel>({
  name: 'animals',
  defaults: [
    animals: []
  ]
})
@Injectable()
export class AnimalState {

  constructor(private store: Store) {}

  @Action(GetAnimals)
  getAnimals(ctx: StateContext<AnimalStateModel>) {
    const state = ctx.getState();

    // select the snapshot state from preferences
    const sort = this.store.selectSnapshot(PreferencesState.getSort);

    // do sort magic here
    return state.sort(sort);
  }

}
```


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