如何获得状态的最后值?不带下标(rxJs)

Question

我在门面上有这个

chatMessagesState$ = this.store.pipe(select(ChatMessageSelectors.getChatMessagesState));

this on selector

export const getChatMessagesState = createSelector(
getChatMessages,
(payload: ChatMessagesState) => payload
);

和这个组件

this.chatMessagesSub = this.chatMessagesFacade.chatMessagesState$.subscribe(state => {
if (state.messages) {
// do something
}
});

如何获取状态而不订阅?

Answer 1

constructor(private storeState: State<YourState>)
const state = this.storeState.value['your-state'];

如果你只需要取一次值

Answer 2

一种方法是将Observable转换为Promise并使用async-await:

async getStateValue(){
const state=await this.chatMessagesFacade.chatMessagesState$.toPromise();
return state;
}

注意:这种方法违背了可观察对象的目的，因为您将无法侦听发出的更改。Promise将只解析/拒绝一次。