使用泛型获取属性信息 [英] Get Attribute info with generics

问题描述

实际上，我可以通过在我的OE中这样做一个表字段和变量之间的关系：

actually, I can make a relation between a table field and a variable by doing this inside my OE:

public class MyOE
{
  [Column("AGE_FIELD")]
  public int ageField { get; set; }
}

我的OE类只需要使用这个类：

My OE class just need to use this other class:

[AttributeUsage(AttributeTargets.Property, Inherited = true, AllowMultiple = true)]
public class ColumnAtt : Attribute
{
  private string name;

  public string Name
  {
    get { return name; }
  }

  public ColumnAtt (string name)
  {
     this.name = name;
  }  
}

使用上面的代码，方法，我将需要获取列值。

Well, using the code above, Im doing a generic method that I will need to get the "Column" value. How I could do that?

这里是我的方法：

public void CompareTwoObjectsAndSaveChanges<TObjectType>(TObjectType objectA, TObjectType objectB )
{
    if(objectA.GetType() == objectB.GetType())
    {
       foreach (var prop in objectA.GetType().GetProperties())
       {
           if(prop.GetValue(objectA, null) != prop.GetValue(objectB, null))
           {
               string colvalue  = "";//Here I need to get the Column value of the attribute.
               string nameOfPropertyThatChanges = prop.Name;
               string objectAValue = prop.GetValue(objectA, null).ToString();
               string objectBValue = prop.GetValue(objectB, null).ToString();

           }
       }   
    }
}

推荐答案

您需要使用反射来获取应用于您的对象的属性。如果你知道属性总是 ColumnAtt ，那么你可以这样做，得到的值：

You need to use reflection to get the attributes applied to your object. If you know the attribute is always going to be ColumnAtt, then you can do something like this to get the value:

public void CompareTwoObjectsAndSaveChanges<TObjectType>(TObjectType objectA, TObjectType objectB )
{
    if(objectA.GetType() == objectB.GetType())
    {
       foreach (var prop in objectA.GetType().GetProperties())
       {
           if(prop.GetValue(objectA, null) != prop.GetValue(objectB, null))
           {
               // Get the column attribute
               ColumnAttr attr = (ColumnAttr)objectA.GetType().GetCustomAttributes(typeof(ColumnAttr), false).First();

               string colValue = attr.Name;
               string nameOfPropertyThatChanges = prop.Name;
               string objectAValue = prop.GetValue(objectA, null).ToString();
               string objectBValue = prop.GetValue(objectB, null).ToString();
           }
       }   
    }
}

使用 GetCustomAttributes（...） 方法。

这篇关于使用泛型获取属性信息的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！