实体Datagrid：添加计算值的最佳方法？ [英] Entity Datagrid : best way to add computed values?

问题描述

我有一个WPF datagrid数据绑定到一个collectionviewsource，它本身是基于一个实体查询

在我的网格中，我有3列Number1，Number2，Number3 ，一个实体的所有属性。如果我想添加一个名为SumNumber的列，等于Number1 + Number2 + Number3，那么最好的方法是什么？当我更改Number1时，SumNumber中的值会被更新？

提前感谢

---

我几乎在那里，但我收到另一个错误。见下面一段代码

  public partial class MyEntity 
 {
 public double MyCustomizedProperty {get; set ;} 
 
 public MyEntity（）
 {
 this.PropertyChanged + = Entity_PropertyChanged; 
} 
 
 void Entity_PropertyChanged（object sender，PropertyChangedEventArgs e）
 {
 switch（e.PropertyName）
 {
 caseDate ：
 MyCustomizedProperty = DateTime.Now.Second; 
 ReportPropertyChanged（MyCustomizedProperty）; 
 break; 
} 
} 
} 
  

当我更改日期时，我得到一个运行时错误：

 属性SigmaFinal没有一个有效的实体映射实体对象。有关更多信息，请参阅实体框架文档。 
  

我想这是因为该属性不在OnStateManager中。你可以让我知道如何解决这个问题吗？

谢谢

解决方案

p>我将创建一个 Converter ，它将采用所有3个值并返回它们的总和，或者我将扩展Entity Framework类以包含额外的属性

以下是扩展EF类以包含额外属性的示例：

 公共部分类MyEntity 
 {
 
 public MyEntity（）
 {
 //挂起PropertyChanged事件以提醒UI 
 //更新Sum当任何值更改
 this.PropertyChanged + = MyEntity_PropertyChanged; 
} 
 
 void MyEntity_PropertyChanged（object sender，PropertyChangedEventArgs e）
 {
 switch e.PropertyName 
 {
 caseValue1：
 caseValue2：
 caseValue3：
 ReportPropertyChanged（SumValues）; 
 break; 
} 
} 
 
 
 public int SumValues 
 {
 get 
 {
返回Value1 + Value2 + Value3 ; 
} 
} 
 
} 
  

I have a WPF datagrid databound to a collectionviewsource, which is itself based of a entity query

In my grid for example I have 3 columns Number1, Number2, Number3, all properties of an entity. If I want to add a column called SumNumber which is equal to Number1+Number2+Number3, what is the best way to do that so that when I change Number1, the value in SumNumber is updated ?

Thanks in advance

---

I'm almost there but I'm getting another error. See below a snippet of code

public partial class MyEntity
{
    public double MyCustomizedProperty{get;set;}

    public MyEntity()
    {
        this.PropertyChanged += Entity_PropertyChanged;
    }

    void Entity_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        switch (e.PropertyName )
        {
            case "Date" :
                MyCustomizedProperty = DateTime.Now.Second;
                ReportPropertyChanged("MyCustomizedProperty");
                break;
        }
    }
}

That compiles and all, but when I change "Date" I get a runtime error :

The property 'SigmaFinal' does not have a valid entity mapping on the entity object. For more information, see the Entity Framework documentation.

I suppose this is due to the fact that the property is not in the OnStateManager. Can you please let me know how to fix that ?

Thanks

解决方案

I would either create a Converter that would take all 3 values and return the sum of them, or I would expand the Entity Framework class to include an extra property

Here's an example of expanding the EF class to include the extra property:

public partial class MyEntity
{

    public MyEntity()
    {
        // Hook up PropertyChanged event to alert the UI
        // to update the Sum when any of the Values change
        this.PropertyChanged += MyEntity_PropertyChanged;
    }

    void MyEntity_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        switch e.PropertyName
        {
            case "Value1":
            case "Value2":
            case "Value3":
                ReportPropertyChanged("SumValues");
                break;
        }
    }


    public int SumValues
    {
        get
        {
            return Value1 + Value2 + Value3;
        }
    }

}

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