通過模型更新集合而不創建新行

Question

在我的MVC3應用程序中，我有一堆「SubscriptionTariffs」，每個都與一些「SubscriptionServices」相關。我創建了一個視圖，可以編輯這些關稅並編輯通過服務模型傳遞的集合。

問題是，無論何時提交表單，而不是編輯數據庫中的現有服務，它都會爲每個附加服務創建一個新行。

這裏是我的控制器的方法：

/// <summary> 
    /// Function Edit 
    /// </summary> 
    /// <param name="subscriptionViewModel"></param> 
    /// <returns></returns> 
    [HttpPost] 
    public ActionResult Edit(SubscriptionViewModel subscriptionViewModel) 
    { 
     if (subscriptionViewModel == null) throw new ArgumentException("The value of subscriptionViewModel cannot be null.", "subscriptionViewModel"); 

     Gateway.Instance.Logger.LogDebug("SubscriptionController Edit: Method entered."); 

     using (_ownerManager) 
     { 
      var mappedSubscription = Mapper.Map<SubscriptionTariff>(subscriptionViewModel); 
      _ownerManager.SaveSubscription(mappedSubscription); 
     } 

     Gateway.Instance.Logger.LogDebug("SubscriptionController Edit: Method exited."); 

     return RedirectToAction("Index"); 
    } 

，哪些應該在數據庫上運行的查詢管理器的部分：

var userTariff = (from s in this.Database.SubscriptionTariffs 
            where s.SubscriptionTariffId.Equals(subscriptionTariff.SubscriptionTariffId) 
            select s).FirstOrDefault(); 

    userTariff.SubscriptionTariffId = subscriptionTariff.SubscriptionTariffId; 
    userTariff.Name = subscriptionTariff.Name; 
    userTariff.Description = subscriptionTariff.Description; 
    userTariff.IsActive = subscriptionTariff.IsActive; 
    userTariff.PricePerMonth = subscriptionTariff.PricePerMonth; 
    userTariff.CurrencyCode = subscriptionTariff.CurrencyCode; 
    userTariff.PaymentServiceProvider = subscriptionTariff.PaymentServiceProvider; 
    userTariff.IncomingMaxTransactionPerMonth = subscriptionTariff.IncomingMaxTransactionPerMonth; 
    userTariff.OutgoingMaxTransactionPerMonth = subscriptionTariff.OutgoingMaxTransactionPerMonth; 

    userTariff.SubscriptionServices = subscriptionTariff.SubscriptionServices; 

    this.Database.SaveChanges(); 
    Gateway.Instance.Logger.LogDebug("SaveSubscription method exited"); 
    return subscriptionTariff.SubscriptionTariffId; 

關稅是更新很好，但我可以」讓服務得到更新。如果有人能給我一隻手，將不勝感激！

編輯：

也可能有用，包括ViewModel！

/// <summary> 
    /// 
    /// </summary> 
    public int SubscriptionTariffId { get; set; } 

    /// <summary> 
    /// 
    /// </summary> 
    public string Name { get; set; } 

    /// <summary> 
    /// 
    /// </summary> 
    public string Description { get; set; } 

    /// <summary> 
    /// 
    /// </summary> 
    public bool IsActive { get; set; } 

    /// <summary> 
    /// 
    /// </summary> 
    public decimal PricePerMonth { get; set; } 

    /// <summary> 
    /// 
    /// </summary> 
    public string CurrencyCode { get; set; } 

    /// <summary> 
    /// 
    /// </summary> 
    public string PaymentServiceProvider { get; set; } 

    /// <summary> 
    /// Gets or sets the outgoing max transaction per month. 
    /// </summary> 
    /// <value>The outgoing max transaction per month.</value> 
    public int OutgoingMaxTransactionPerMonth { get; set; } 

    /// <summary> 
    /// Gets or sets the incoming max transaction per month. 
    /// </summary> 
    /// <value>The incoming max transaction per month.</value> 
    public int IncomingMaxTransactionPerMonth { get; set; } 

    /// <summary> 
    /// 
    /// </summary> 
    public virtual ICollection<SubscriptionService> SubscriptionServices { get; set; } 

Answer 1

的

userTariff.SubscriptionServices = subscriptionTariff.SubscriptionServices; 

insted的請嘗試

subscriptionTariff.SubscriptionServices.ToList().ForEach(ss => 
    { 
     // get the instance of the correct subscriptionTariff using the 
     // id (IdOfSubscriptionServices) 
     var u = userTariff.SubscriptionServices.FirstOrDefault(e => e.IdOfSubscriptionServices == ss.IdOfSubscriptionServices); 

     if (u != null) 
     { 
      // update each property 
      u.Prop1 = ss.Prop1; 
      u.Prop2 = ss.Prop2; 
     } 
    });