使用反射从类列表中的属性中获取值

本文关键字：属性 获取 列表 反射 | 更新日期: 2023-09-27 18:35:12

我正在尝试从作为主对象一部分的列表内的对象中获取值。

我有一个主要对象，其中包含各种可以成为集合的属性。

现在我正在尝试弄清楚如何访问对象中包含的通用列表。

///<summary>
///Code for the inner class
///</summary>
public class TheClass
{
    public TheClass();
    string TheValue { get; set; }
} //Note this class is used for serialization so it won't compile as-is
///<summary>
///Code for the main class
///</summary>
public class MainClass
{
    public MainClass();
    public List<TheClass> TheList { get; set; }
    public string SomeOtherProperty { get; set; }
    public Class SomeOtherClass { get; set }
}

public List<MainClass> CompareTheValue(List<object> MyObjects, string ValueToCompare)
{ 
    //I have the object deserialised as a list
    var ObjectsToReturn = new List<MainClass>();
    foreach(var mObject in MyObjects)
    {
        //Gets the properties
        PropertyInfo piTheList = mObject.GetType().GetProperty("TheList");
        object oTheList = piTheList.GetValue(MyObject, null);

        //Now that I have the list object I extract the inner class 
        //and get the value of the property I want
        PropertyInfo piTheValue = oTheList.PropertyType
                                          .GetGenericArguments()[0]
                                          .GetProperty("TheValue");
        //get the TheValue out of the TheList and compare it for equality with
        //ValueToCompare
        //if it matches then add to a list to be returned
        //Eventually I will write a Linq query to go through the list to do the comparison.
        ObjectsToReturn.Add(objectsToReturn);
    }
return ObjectsToReturn;
}

我试图在这个问题上使用 MyObject 的SetValue()，但它错误（释义）：

对象不是类型

private bool isCollection(PropertyInfo p)
{
    try
    {
        var t = p.PropertyType.GetGenericTypeDefinition();
        return typeof(Collection<>).IsAssignableFrom(t) ||
               typeof(Collection).IsAssignableFrom(t);
    }
    catch
    {
        return false;
    }
    }
}

使用反射从类列表中的属性中获取值

要使用反射获取/设置，您需要一个实例。 要遍历列表中的项目，请尝试以下操作：

PropertyInfo piTheList = MyObject.GetType().GetProperty("TheList"); //Gets the properties
IList oTheList = piTheList.GetValue(MyObject, null) as IList;
//Now that I have the list object I extract the inner class and get the value of the property I want
PropertyInfo piTheValue = piTheList.PropertyType.GetGenericArguments()[0].GetProperty("TheValue");
foreach (var listItem in oTheList)
{
    object theValue = piTheValue.GetValue(listItem, null);
    piTheValue.SetValue(listItem,"new",null);  // <-- set to an appropriate value
}

看看这样的事情是否有助于您朝着正确的方向前进： 不久前我遇到了同样的错误，这段代码截断解决了我的问题。

PropertyInfo[] properties = MyClass.GetType().GetProperties();
foreach (PropertyInfo property in properties)
{
  if (property.Name == "MyProperty")
  {
   object value = results.GetType().GetProperty(property.Name).GetValue(MyClass, null);
   if (value != null)
   {
     //assign the value
   }
  }
}
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