Question

infiniteHandler($state) {
    var next = db
        .collection("posts")
        .orderBy("timestamp", "desc")
        .startAfter(this.lastVisible)
        .limit(3)

    next.get().then(documentSnapshots => {
        //Get the last visible document
        // this.lastVisible =
        // documentSnapshots.docs[documentSnapshots.docs.length - 1]

        if (documentSnapshots.docs.length == 0) $state.complete()
        else {
            this.$store.commit(
                "modules/posts/updateLastVisible",
                documentSnapshots.docs[documentSnapshots.docs.length - 1].data()
                .timestamp
            )
        }

        documentSnapshots.forEach(doc => {
            var post = doc.data()
            post.docID = doc.id
            this.$store.commit("modules/posts/pushPost", post)
        })
        $state.loaded()
    })
}

这是我的无限加载处理程序，一旦到达列表的末尾，它将获取新的数据库条目。到目前为止工作正常。

这是我在加载页面时的第一个抓取内容

async fetch({ store }){
    if (store.state.modules.posts.posts.length < 5) {
        let posts = []
        await db
            .collection("posts")
            .orderBy("timestamp", "desc")
            .limit(3)
            .get()
            .then(querySnapshot => {
                store.commit(
                    "modules/posts/updateLastVisible",
                    querySnapshot.docs[2].data().timestamp
                )
                querySnapshot.forEach(doc => {
                    var x = doc.data()
                    x.docID = doc.id
                    posts.push(x)
                })
            })
        store.commit("modules/posts/fetchedPosts", posts)
    }
}

基本上，问题是当我在无限加载处理程序中进行获取时，我再次获取了页面加载时获取的前3个条目，这导致条目被显示两次，因为{{1} }具有我在加载时获取的第3个元素的时间戳，因此应将其忽略。

在这些元素之后，this.lastVisible都可以正常工作，但是再次加载前3个没有意义。我用devtools检查了商店，一切正常，当第一次调用infiniteLoading Handler时，.startAfter的值正确。

赏金编辑：好的，所以我仍然遇到尝试尝试解决该问题的问题，但问题仍然存在……我将悬赏，希望任何人都能提供帮助。

Answer 1

您实际上不需要第一次获取。挂载infiniteHandler时将单独调用它。如果没有调用，您可以尝试使用函数

this。$ refs.infiniteLoading.attemptLoad（）; //'infiniteLoading'是组件的ref属性

这实际上将为您调用infiniteHandler函数。

编辑：检查功能之一当前是否正在运行。在处理程序部分

infiniteHandler($state) {
    //Check if its currently loading
    this.$nextTick(()=>{
       if (this.isDocSnapShotLoading){
           return;
       }
    });

    //set as currently loading
    this.isDocSnapShotLoading = true;

    var next = db
        .collection("posts")
        .orderBy("timestamp", "desc")
        .startAfter(this.lastVisible)
        .limit(3)

    next.get().then(documentSnapshots => {
        //Get the last visible document
        // this.lastVisible =
        // documentSnapshots.docs[documentSnapshots.docs.length - 1]

        if (documentSnapshots.docs.length == 0) $state.complete()
        else {
            this.$store.commit(
                "modules/posts/updateLastVisible",
                documentSnapshots.docs[documentSnapshots.docs.length - 1].data()
                .timestamp
            )
        }

        documentSnapshots.forEach(doc => {
            var post = doc.data()
            post.docID = doc.id
            this.$store.commit("modules/posts/pushPost", post)
        })
        $state.loaded()

        //set completed loading
        this.isDocSnapShotLoading = false;
    })
}

在获取部分

async fetch({ store }){
    if (store.state.modules.posts.posts.length < 5) {

        //check if currently loading
        this.$nextTick(()=>{
           if (this.isDocSnapShotLoading){
              return;
           }
       });

        //set as currently loading
        this.isDocSnapShotLoading = true;

        let posts = []
        await db
            .collection("posts")
            .orderBy("timestamp", "desc")
            .limit(3)
            .get()
            .then(querySnapshot => {
                store.commit(
                    "modules/posts/updateLastVisible",
                    querySnapshot.docs[2].data().timestamp
                )
                querySnapshot.forEach(doc => {
                    var x = doc.data()
                    x.docID = doc.id
                    posts.push(x)
                })

                //set as completed loading.
                this.isDocSnapShotLoading = false;
            })
        store.commit("modules/posts/fetchedPosts", posts)
    }
}

Answer 2

如果您想忽略infiniteHandler中的前3个帖子，则可以创建一个帖子数组，在其中存储帖子ID并检查帖子ID是否已加载。我知道应该使用查询解决此问题，但作为临时解决方案，我希望它对您有用。

infiniteHandler($state) {
    var next = db
        .collection("posts")
        .orderBy("timestamp", "desc")
        .startAfter(this.lastVisible)
        .limit(3)

    next.get().then(documentSnapshots => {
        //Get the last visible document
        // this.lastVisible =
        // documentSnapshots.docs[documentSnapshots.docs.length - 1]

        if (documentSnapshots.docs.length == 0) $state.complete()
        else {
            this.$store.commit(
                "modules/posts/updateLastVisible",
                documentSnapshots.docs[documentSnapshots.docs.length - 1].data()
                .timestamp
            )
        }

        documentSnapshots.forEach(doc => {
            var check = this.postIdArray.indexOf(doc.id);
            if(check == -1){
                var post = doc.data()
                post.docID = doc.id
                this.$store.commit("modules/posts/pushPost", post);
                this.postIdArray[] = doc.id;
            }
        })
        $state.loaded()
    })
}



async fetch({ store }){
    this.postIdArray = [];
    if (store.state.modules.posts.posts.length < 5) {
        let posts = []
        await db
            .collection("posts")
            .orderBy("timestamp", "desc")
            .limit(3)
            .get()
            .then(querySnapshot => {
                store.commit(
                    "modules/posts/updateLastVisible",
                    querySnapshot.docs[2].data().timestamp
                )
                querySnapshot.forEach(doc => {
                    var x = doc.data()
                    x.docID = doc.id
                    this.postIdArray[] = doc.id;
                    posts.push(x)
                })
            })
        store.commit("modules/posts/fetchedPosts", posts)
    }
}

Answer 3

好吧，所以我找到了一个暂时的解决方案，该解决方案目前可以使用，但是仍然不够漂亮：

documentSnapshots.forEach(doc => {
          if (
            doc.id !== this.posts[0].docID &&
            doc.id !== this.posts[1].docID &&
            doc.id !== this.posts[2].docID
          ) {
            var post = doc.data()
            post.docID = doc.id
            this.$store.commit("modules/posts/pushPost", post)
          }
        })

我也尝试通过不同的解决方案来提高效率，谢谢您的帮助。

Firestore .startAt无法正常工作

3 个答案: