React Native Redux在删除时触发实时更改

Question

我正在用Redux和Firebase/Firestore构建一个React原生社交媒体应用程序，我需要实现一个Following屏幕，其中用户可以实时看到他在关注谁。

我已经设法完成了，让一切都工作，除了删除部分。当一个用户在redux存储中被添加到以下列表中，然后被删除时，他不会被删除。

我让它工作的方式如下:firestore集合上的一个监听器，每当一个用户被关注/取消关注时，他将成功地从后面的中添加/删除。状态。然后，我在Redux中有一个操作，从跟随中获取每个id，并将该用户的所有数据收集到另一个状态followwedusers(在following状态下，他只获取用户的id，并使用该id从用户集合中获取数据，然后将这些数据分派到followwedusers状态)。

下面是动作

export const followingState = () => {
return((dispatch) => {
firebase
.firestore()
.collection("following")
.doc(firebase.auth().currentUser.uid)
.collection("userFollowing")
.onSnapshot((snapshot) => {
let following = snapshot.docs.map(doc => {
return doc.id;
})

dispatch({type : FOLLOWING_STATE, following });

for(let j = 0; j < following.length; j++){
dispatch(followedUsersState(following[j]));
};
})
});
}; 


export const followedUsersState = (uid) => {
return((dispatch) => {


firebase
.firestore()
.collection("allUsers")
.doc(uid)
.get()
.then((snapshot) => {

let user =  {snapshot.id, ...snapshot.data()};

dispatch({type : USERS_FOLLOWED_STATE, user});

});
})
} 

还原剂也:

case FOLLOWING_STATE:
return {
...state,
following: action.following
};

case FOLLOWED_USERS_STATE:
return {
...state,
followedUsers: [...state.followedUsers, action.user]
};

Answer 1

我认为问题出在你的"followwed_users_state"action reducer，通过调用followedUsers:[...state.followedUsers,action.user]，你保持followedUsers的旧状态，并在每次.collection("userFollowing").onSnapshot(...)火灾时添加新用户，我认为你应该尝试一次调度users_followwed_state与用户数组，这样你就刷新了整个数组，我希望这能帮助

export const followingState = () => {
return((dispatch) => {
firebase
.firestore()
.collection("following")
.doc(firebase.auth().currentUser.uid)
.collection("userFollowing")
.onSnapshot((snapshot) => {
let following = snapshot.docs.map(doc => {
return doc.id;
})

dispatch({type : FOLLOWING_STATE, following });

// get all users data from db in one go
const proms = following.map((id)=>{
return getFollowedUserState(id)
})

Promise.all(proms).then((snapshots)=>{

const users = snapshots.map((snapshot)=>{
return {id:snapshot.id, ...snapshot.data()};
})

// set all users data to local state in one go
dispatch({type : USERS_FOLLOWED_STATE, users});
})

})
});
}; 

const getFollowedUserState = (uid)=>{
return firebase
.firestore()
.collection("allUsers")
.doc(uid)
.get()
}

case FOLLOWING_STATE:
return {
...state,
following: action.following
};
case FOLLOWED_USERS_STATE:
return {
...state,
followedUsers: action.users
};