javascript - Firebase Cloud Firestore错误+ Vue + Vuex(firebase.firestore.QuerySnapshot)

我发现docchanges有问题，这是一个函数，但是当我写docChanges().doc.data().userId时，会出现这个错误store.js?3bf3:21 Uncaught TypeError: Cannot read property 'doc' of undefined
●更新
我想登录/注册，但我现在收到这个错误
一切正常，但登录函数中的this.$router.push('/dashboard')不正常。为什么？
商店.js

state: {
  currentUser: null,
  userProfile: {},
  posts: [],
  hiddenPosts: []
},
actions: {
    clearData({ commit }) {
        commit('setCurrentUser', null)
        commit('setUserProfile', {})
        commit('setPosts', null)
    },
    fetchUserProfile({ commit, state }) {
        fb.usersCollection.doc(state.currentUser.uid).get().then(res => {
            commit('setUserProfile', res.data())
        }).catch(err => {
            console.log(err)
        })
    }
},
mutations: {
    setCurrentUser(state, val) {
        state.currentUser = val
    },
    setUserProfile(state, val) {
        state.userProfile = val
    },
    setPosts(state, val) {
        if (val) {
            state.posts = val
        } else {
            state.posts = []
        }
    },
    setHiddenPosts(state, val) {
        if (val) {
            if (!state.hiddenPosts.some(x => x.id === val.id)) {
                state.hiddenPosts.unshift(val)
            }
        } else {
            state.hiddenPosts = []
        }
    }
}

Error code of Login
login.vue组件

             <form v-if="showLoginForm" @submit.prevent>
                <h1>Welcome Back</h1>

                <label for="email1">Email</label>
                <input v-model.trim="loginForm.email" type="text"
                 placeholder="[email protected]" id="email1" />

                <label for="password1">Password</label>
                <input v-model.trim="loginForm.password" type="password"
                  placeholder="******" id="password1" />

                <button @click="login" class="button">Log In</button>
             </form>

        data() {
           return {
              loginForm: {
                email: '',
                password: ''
              }
           }
        },
        methods: {
           login() {
            this.performingRequest = true

            fb.auth.signInWithEmailAndPassword(this.loginForm.email,
              this.loginForm.password).then(user => {
                this.$store.commit('setCurrentUser', user)
                this.$store.dispatch('fetchUserProfile')
                this.performingRequest = false
                this.$router.push('/dashboard')
            }).catch(err => {
                console.log(err)
                this.performingRequest = false
                this.errorMsg = err.message
            })
          },
        }

最佳答案

您调用querySnapshot.docChanges时就好像它是一个数组：

querySnapshot.docChanges.length...
querySnapshot.docChanges[0]...

但是querySnapshot.docChanges是一个函数，所以在返回数组之前需要先调用该函数：

querySnapshot.docChanges().length...
querySnapshot.docChanges()[0]...