更新不同表格時，如何從特定用戶獲取性別？ Azure移動服務

Question

我有一個名爲Subscription的表和另一個名爲Client的表，我需要每次進行更新時擁有訂閱的客戶端的性別。這是我的更新腳本：

function update(item, user, request) { 
    var subscriptionId = item.id; 
    var subscriptionActivitiesTable = tables.getTable("SubscriptionActivity"); 
    var userTable = tables.getTable("User"); 
    var activityTable = tables.getTable("Activity"); 
    var userGender = userTable.where({id: item.UserId}).select('Gender').take(1).read(); 
    console.log(userGender); 
    activityTable.where({PlanId:item.PlanId, Difficulty: item.Difficulty}).read({ 
     success: function(results){ 
      var startDate = item.StartDate; 
      results.forEach(function(activity) 
      { 
       var testDate = new Date(startDate.getFullYear(),startDate.getMonth(), startDate.getDate()); 
       testDate.setDate(testDate.getDate() + activity.Sequence + (activity.Week*7)); 
       subscriptionActivitiesTable.insert({SubscriptionId: subscriptionId, 
       ActivityId: activity.id, ShowDate: new Date(testDate.getFullYear(), 
        testDate.getMonth(), testDate.getDate()), CreationDate: new Date()}); 

      }) 
     } 
    }); 

    var planWeeks = 12;//VER DE DONDE SACAMOS ESTE NUMERO 
    var idealWeight = 0; 
    if (userGender === "Male") 
    { 
     idealWeight = (21.7 * Math.pow(parseInt(item.Height)/100,2));  
    } 
    else 
    { 
     idealWeight = (23 * Math.pow(parseInt(item.Height)/100,2)); 
    } 

    var metabolismoBasal = idealWeight * 0.95 * 24; 
    var ADE = 0.1 * metabolismoBasal; 
    var activityFactor; 
    if (item.Difficulty === "Easy") 
    { 
     activityFactor = 1.25; 
    } 
    else if(item.Difficulty === "Medium") 
    { 
     activityFactor = 1.5; 
    } 
    else 
    { 
     activityFactor = 1.75; 
    } 
    var caloricRequirement = ((metabolismoBasal + ADE)*activityFactor); 
    activityTable.where(function(item, caloricRequirement){ 
     return this.PlanId === item.PlanId && this.Type != "Sport" && 
     this.CaloricRequirementMin <= caloricRequirement && 
     this.CaloricRequirementMax >= caloricRequirement;}, item, caloricRequirement).read({ 
     success: function(results) 
     { 
      var startDate = item.StartDate; 
      results.forEach(function(activity) 
      { 
       for (var i=0;i<planWeeks;i++) 
       { 
        var testDate = new Date(startDate.getFullYear(),startDate.getMonth(), startDate.getDate()); 
        testDate.setDate(testDate.getDate() + activity.Sequence + (i*7)); 
        subscriptionActivitiesTable.insert({SubscriptionId: subscriptionId, 
        ActivityId: activity.id, ShowDate: new Date(testDate.getFullYear(), 
        testDate.getMonth(), testDate.getDate()), CreationDate: new Date()}); 
       } 
      }) 
     } 
    }) 
    request.execute(); 
} 

我試過上面的代碼，clientGender是未定義的。正如你所看到的，我想用性別來設定理想的重量。

Answer 1

read()方法需要傳入一個函數success參數 - 它不返回查詢的結果，就像您想象的那樣。

嘗試這樣代替：

function update(item, user, request) { 
    var clientTable = tables.getTable("Client"); 
    var clientGender = 'DEFAULT'; 
    clientTable.where({id: item.ClientId}).select('Gender').take(1).read({ 
     success: function(clients) { 
      if (clients.length == 0) { 
       console.error('Unable to find client for id ' + item.ClientId); 
      } else { 
       var client = client[0]; 
       clientGender = client.Gender; 

       // since we're inside the success function, we can continue to 
       // use the clientGender as it will reflect the correct value 
       // as retrieved from the database 
       console.log('INSIDE: ' + clientGender); 
      } 
     } 
    }); 

    // this is going to get called while the clientTable query above is 
    // still running and will most likely show a value of DEFAULT 
    console.log('OUTSIDE: ' + clientGender); 

} 

在此示例中，客戶端表查詢時拉開序幕，隨着success參數提供一個回調函數。查詢完成後，將調用回調函數，並將結果數據顯示在日誌中。同時 - 在查詢仍在運行時，即 - 運行流暢代碼之後的下一個語句，將執行另一個console.log語句，以顯示read函數之外的clientGender字段的值。此代碼將在read語句仍在數據庫中等待時運行。輸出應該是這個樣子的WAMS日誌：

* INSIDE: Male 
* OUTSIDE: Default 

由於日誌顯示在底部的最古老的項目，你可以看到，外面的日誌條目裏面日誌前一段時間寫的。

如果你不習慣異步或函數式編程，這可能看起來很奇怪，但據我發現，這現在是節點的作品。嵌套在函數中的函數嵌套在函數中可能會有些嚇人，但如果你提前計劃，它可能不會太糟糕:-)