如何分頁包含equalTo（）api的firebase查詢

Question

我使用firebase編碼購物網站。 我有一些類別和子類別在側邊欄，onClick他們，帖子提要應相應更新，按時間排序，只顯示選定類別的帖子。在火力數據庫

後對象：

-KiKGQUZ4XaZPHxvOZD-addclose { 
     categorie:0 
     subCat: 2 
     .... 
    } 

有很多帖子，我需要分頁他們

要做到這一點，我應該這樣的查詢：

dbRef 
    .orderByChild('categories') 
    .equalTo(category) 
    .limitToLast(QUERY.PAGINATION_COUNT) 
    .on('value', (snapshot) => { 
     cb(_toArray(snapshot).reverse()); 
    }); 

但我無法與equalTo（）分頁。

我認爲解決的辦法應該是：

dbRef 
    .orderByChild('categories') 
    .equalTo(category) 
    .startAt(lastFetchedItem.fbKey) 
    .limitToLast(QUERY.PAGINATION_COUNT) 
    .on('value', (snapshot) => { 
     cb(_toArray(snapshot).reverse()); 
    }); 

但它不是用火力可以做到equalTo查詢和startAt的同時

如何，我可以解決這個問題？

Answer 1

我最終更改了firebase實時數據庫模式。

我不確定，但我認爲firebase有意不釋放更多apis。它迫使你仔細檢查你的模式並改進它。

我已經創建了專門的類別集合和類別集合，爲每個類別創建了單獨的節點。 它用什麼firebase recommend來構建你的數據庫。

然後將每個新帖子放入相應的類別。

所以我可以輕鬆地使用在每個類別和子類別​​和使用startAt或endAt的API

的另一個解決方案是使用火力的功能和彈性的搜索分頁他們。已爲此創建了 FlashLight package。

Answer 2

基於this source它看起來像這個功能是不可能的，不會被添加。您可以使用equalTo

你的最後一個可見密鑰查詢的關鍵結局做這樣的事情，雖然

1. 查詢您最初的尋呼量，如果該類別相匹配你想要然後將其添加了一個過濾結果，否則忽略它。

我在Swift3中編寫了我的代碼，但也有同樣的問題，也許我的代碼會對其他人有所幫助。

static func filterTableByCategory(tableNumber: String, category: String) { 
     filteringRef.child(tableNumber).queryOrdered(byChild: "category").queryEqual(toValue: category).queryLimited(toLast: 9).observeSingleEvent(of: .value, with: { snap in 

      if snap.exists() { 
       currentTablePosts.removeAll() 
       for child in snap.children { 
        let child = child as? DataSnapshot 
        if let post = child?.value as? [String: AnyObject] { 
         let posst = Post() 
         if let author = post["author"] as? String, let likes = post["likes"] as? Int, let pathToImage = post["pathToImage"] as? String, let postID = post["postID"] as? String, let postDescription = post["postDescription"] as? String, let timestamp = post["timestamp"] as? Double, let category = post["category"] as? String, let table = post["group"] as? String, let userID = post["userID"] as? String, let numberOfComments = post["numberOfComments"] as? Int, let region = post["region"] as? String { 

          posst.author = author 
          posst.likes = likes 
          posst.pathToImage = pathToImage 
          posst.postID = postID 
          posst.userID = userID 
          posst.fancyPostDescription = Helper.createAttributedString(author: author, postText: postDescription) 
          posst.postDescription = author + ": " + postDescription 
          posst.timestamp = timestamp 
          posst.table = table 
          posst.region = region 
          posst.category = category 
          posst.numberOfComments = numberOfComments 
          posst.userWhoPostedLabel = Helper.createAttributedPostLabel(username: author, table: table, region: region, category: category) 

          if let people = post["peopleWhoLike"] as? [String: AnyObject] { 
           for(_, person) in people { 
            posst.peopleWhoLike.append(person as! String) 
           } 
          } 
          currentTablePosts.insert(posst, at: 0) 
          NotificationCenter.default.post(name: NSNotification.Name(rawValue: "reloadTableCollectionView"), object: nil) 
         } // end of if let 
        } 
       } 
      } 
      else { 
       currentTablePosts.removeAll() 
       NotificationCenter.default.post(name: NSNotification.Name(rawValue: "reloadTableCollectionView"), object: nil) 
      } 
     }) 
     filteringRef.removeAllObservers() 
    } 

    static func getMoreFilterByCategoryPosts(tableNumber: String, category: String, lastVisibleKey: String) { 

     pagingReference.child(tableNumber).queryOrderedByKey().queryEnding(atValue: lastVisibleKey).queryLimited(toLast: 12).observeSingleEvent(of: .value, with: { snap in 

      if snap.exists() { 
       let currentNumberOfPosts = currentTablePosts.count 
       for child in snap.children { 
        let child = child as? DataSnapshot 
        if let post = child?.value as? [String: AnyObject] { 
         if let cat = post["category"] as? String, let postID = post["postID"] as? String { 
          if cat == category && postID != lastVisibleKey { 
           let posst = Post() 
           if let author = post["author"] as? String, let likes = post["likes"] as? Int, let pathToImage = post["pathToImage"] as? String, let postDescription = post["postDescription"] as? String, let timestamp = post["timestamp"] as? Double, let table = post["group"] as? String, let userID = post["userID"] as? String, let numberOfComments = post["numberOfComments"] as? Int, let region = post["region"] as? String { 

            posst.author = author 
            posst.likes = likes 
            posst.pathToImage = pathToImage 
            posst.postID = postID 
            posst.userID = userID 
            posst.fancyPostDescription = Helper.createAttributedString(author: author, postText: postDescription) 
            posst.postDescription = author + ": " + postDescription 
            posst.timestamp = timestamp 
            posst.table = table 
            posst.region = region 
            posst.category = cat 
            posst.numberOfComments = numberOfComments 
            posst.userWhoPostedLabel = Helper.createAttributedPostLabel(username: author, table: table, region: region, category: category) 

            if let people = post["peopleWhoLike"] as? [String: AnyObject] { 
             for(_, person) in people { 
              posst.peopleWhoLike.append(person as! String) 
             } 
            } 
            currentTablePosts.insert(posst, at: currentNumberOfPosts) 
            NotificationCenter.default.post(name: NSNotification.Name(rawValue: "reloadTableCollectionView"), object: nil) 
           } // end of if let 
          } 
         } 
        } 
       } 
      } 
      else { 
       print("snap == nil") 
      } 

     }) 
     pagingReference.removeAllObservers() 

    }