Context.Entry（）。GetDatabaseValues（）方法不会复制实体的子节点 [英] Context.Entry().GetDatabaseValues() method doesn't copy entity's children

问题描述

我正在使用实体框架处理WPF项目。我使用 Context.Entry（）。GetDatabaseValues（）方法获取正在更新的对象的原始对象值。 .GetDatabaseValues（）方法返回内部对象的空值的原始值

如下所示：

  public partial class LabPayments 
 {
 public partial class LabAccount 
 {
 public long ID {get;组; } 
 public Nullable< long> MaterialID {get;组; } 
 public Nullable< long> LabID {get;组; } 
 public Nullable< double>数量{get;组; } 
 public Nullable< System.DateTime> MaterialDate {get;组; } 
 public Nullable< long> LabMaterialPriceID {get;组; } 
 public Nullable< decimal>价格{get;组; } 
 
 public virtual Lab Lab {get;组; } 
 public virtual LabMaterial LabMaterial {get;组; } 
 public virtual LabMaterialPrice LabMaterialPrice {get;组; 
} 
  

返回的虚拟对象值为null !!

解决方案

从MSDN：

查询数据库的副本跟踪的实体的值目前存在于数据库中。

^{_{https://msdn.microsoft.com/en-us/library/system.data.entity。 infrastructure.dbentityentry.getdatabasevalues（v = vs.113）.aspx}}

  using（var context = new BloggingContext（））
 {
 var blog = context .Blogs.Find（1）; 
 
 var clonedBlog = context.Entry（blog）.GetDatabaseValues（）。ToObject（）; 
} 
  

请注意，返回的对象不是实体，也没有被跟踪上下文。返回的对象也没有与其他对象设置任何关系。

^{_{https://msdn.microsoft.com/en-us/data/jj592677.aspx}}

---

GetDatabaseValues 获取值仅用于跟踪的实体，而不是任何导航属性或集合属性，它们只是关系/关联的表示。这些虚拟属性是对相关实体对象的引用，不会以 GetDatabaseValues 返回。

I am working on a WPF project with Entity Framework. I used the Context.Entry().GetDatabaseValues() method to get original object values for the object being updated. The .GetDatabaseValues() method returns original value with null values for inner objects

As the following :

public partial class LabPayments 
{
   public partial class LabAccount
   {
    public long ID { get; set; }
    public Nullable<long> MaterialID { get; set; }
    public Nullable<long> LabID { get; set; }
    public Nullable<double> Quantity { get; set; }
    public Nullable<System.DateTime> MaterialDate { get; set; }
    public Nullable<long> LabMaterialPriceID { get; set; }
    public Nullable<decimal> Price { get; set; }

    public virtual Lab Lab { get; set; }
    public virtual LabMaterial LabMaterial { get; set; }
    public virtual LabMaterialPrice LabMaterialPrice { get; set; }
}

The returned virtual object values are null !!

解决方案

From MSDN:

Queries the database for copies of the values of the tracked entity as they currently exist in the database.
^{_{https://msdn.microsoft.com/en-us/library/system.data.entity.infrastructure.dbentityentry.getdatabasevalues(v=vs.113).aspx}}

using (var context = new BloggingContext()) 
{ 
    var blog = context.Blogs.Find(1); 

    var clonedBlog = context.Entry(blog).GetDatabaseValues().ToObject(); 
}

Note that the object returned is not the entity and is not being tracked by the context. The returned object also does not have any relationships set to other objects.
^{_{https://msdn.microsoft.com/en-us/data/jj592677.aspx}}

---

GetDatabaseValues gets the values only for the tracked entity, not any navigation properties or collection properties, which are only representations of a relationship/association. Those virtual properties are references to related entity objects and won't be returned with GetDatabaseValues.

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