c#-如何迭代类字段和设置属性

我不确定这是否可行，但我希望在不显式引用field对象的情况下迭代类并设置field member属性：

public class Employee
{
  public Person _person = new Person();

  public void DynamicallySetPersonProperty()
  {
    MemberInfo[] members = this.GetType().GetMembers();

    foreach (MemberInfo member in members.Where(a => a.Name == "_person"))
    //get the _person field
    {

      Type type = member.GetType();
      PropertyInfo prop = type.GetProperty("Name"); //good, this works, now to set a value for it

      //this line does not work - the error is "property set method not found"
      prop.SetValue(member, "new name", null);
    }
  }
}


public class Person
{
  public string Name { get; set; }
}

在我标记为您需要添加的答案中：

  public static bool IsNullOrEmpty(this string source)
  {
    return (source == null || source.Length > 0) ? true : false;
  }

---

您正在尝试设置Employee类的_person字段的Name属性。它没有。试试这个：

prop.SetValue(((FieldInfo)member).GetValue(this), "new name", null)

不确定是否需要像这样强制转换第一个参数：

prop.SetValue((Person)((FieldInfo)member).GetValue(this), "new name", null)

---

然后将其应用于_person字段的值。

您试图对变量

member

的属性

Name

执行

SetValue（）

，该属性是MemberInfo对象，并且该项目是只读的

注意：您不需要迭代所有memeber，也不需要使用反射获取字段

\u person

，因为它与方法

DynamicallySetPersonProperty（）

在同一类中定义

所以代码应该是这样读的

PropertyInfo property = this._person.GetType().GetProperty("Name");

property.SetValue(this._person, "new name", null);

如果

\u person

为空，则第一行将失败。因此，您可以使用reflectiopn获取字段的类型

FieldInfo field = this.GetType().GetField("_person", BindingFlags.Public);

PropertyInfo property = field.FieldType.GetProperty("Name");

但是现在，如果

\u person

为空，访问此属性仍将失败

property.Setvalue(field.GetValue(this), "new name", null);

---

下面是一个完整的工作示例：

public class Person
{
    public string Name { get; set; }
}

class Program
{
    static void PropertySet(object p, string propName, object value)
    {
        Type t = p.GetType();
        PropertyInfo info = t.GetProperty(propName);
        if (info == null)
            return;
        if (!info.CanWrite)
            return;
        info.SetValue(p, value, null);
    }

    static void PropertySetLooping(object p, string propName, object value)
    {
        Type t = p.GetType();
        foreach (PropertyInfo info in t.GetProperties())
        {
            if (info.Name == propName && info.CanWrite)
            {
                info.SetValue(p, value, null);
            }
        }
    }

    static void Main(string[] args)
    {
        Person p = new Person();

        PropertySet(p, "Name", "Michael Ellis");
        Console.WriteLine(p.Name);
        PropertySetLooping(p, "Name", "Nigel Mellish");
        Console.WriteLine(p.Name);
    }
}

---

编辑：添加了一个循环变量，以便您可以查看如何循环属性信息对象。

使用我创建的以下扩展方法，您可以设置或获取任何属性值，即使它们是嵌套的

GetPropertyValue（customObject，“Property.Nested.Child.Name”）

或设置

SetPropertyValue（customObject，“Property.Nested.Child.Name”，“我的自定义名称”）

希望您觉得它有用。

试试这个：

public static void ApplyPropertyChanges(this object objDest, object objToCopyFrom)
    {
        if (objDest == null)
            throw new ArgumentNullException();
        if (objToCopyFrom == null)
            throw new ArgumentNullException("objToCopyFrom");
        if (objDest.GetType() != objToCopyFrom.GetType())
            throw new Exception("Invalid type. Required: \"" + objDest.GetType().ToString() + "\"");

        foreach (System.Reflection.PropertyInfo piOrig in objDest.GetType().GetProperties())
        {
            object editedVal = objToCopyFrom.GetType().GetProperty(piOrig.Name).GetValue(objToCopyFrom, null);

            piOrig.SetValue(objDest,
            editedVal,
            null);
        }
    }

用法示例：

    public ActionResult Edit(Team editedTeamData)
    {
        if (!ModelState.IsValid)
            return View();

        Team origTeam = (from t in _db.Teams
                         where t.TeamID == editedTeamData.TeamID
                         select t).FirstOrDefault();

        origTeam.ApplyPropertyChanges(editedTeamData);
        _db.SubmitChanges();

        return RedirectToAction("Index");

    }

---

我需要添加var p=person.GetType（）。。。最后我从另一个班级给它打电话，但这不起作用。它应该是

GetProperty

而不是

GetField

。非常好。。。尤其是筑巢。底座的示例更简单，但没有嵌套。另外，对于任何登陆这里的人（像我一样）必须深入了解“扩展”到底是什么，这是一个很好且简洁的解释：这失败了，因为您试图在memberinfo对象上设置属性名称。成员信息有名称，但不是[\u人]的名称。

    [TestFixture]
public class ObjectExtensionsTest
{

    private class MockClass
    {
        public MockClass()
        {
            Nested = new NestedMockClass();
        }

        public string Id { get; set; }
        public string Name { get; set; }

        public string GetOnly { get { return "MockClass"; } }
        public string SetOnly { set { } }

        public NestedMockClass Nested { get; set; }
    }

    private class NestedMockClass
    {
        public string NestedId { get; set; }
        public string NestedName { get; set; }

        public string NestedGetOnly { get { return "NestedMockClass"; } }
        public string NestedSetOnly { set { } }
    }

    [Test]
    public void TestShouldFindProperty()
    {
        MockClass mockObject = new MockClass();

        Assert.IsTrue(mockObject.HasProperty("Id"));
        Assert.IsTrue(mockObject.HasProperty("Name"));
        Assert.IsTrue(mockObject.HasProperty("GetOnly"));
        Assert.IsTrue(mockObject.HasProperty("SetOnly"));
        Assert.IsTrue(mockObject.HasProperty("Nested"));
        Assert.IsTrue(mockObject.HasProperty("Nested.NestedId"));
        Assert.IsTrue(mockObject.HasProperty("Nested.NestedName"));
        Assert.IsTrue(mockObject.HasProperty("Nested.NestedGetOnly"));
        Assert.IsTrue(mockObject.HasProperty("Nested.NestedSetOnly"));
    }

    [Test]
    public void TestShouldGetPropertyValue()
    {
        MockClass mockObject = new MockClass();

        mockObject.Id = "1";
        mockObject.Name = "Name";
        mockObject.Nested.NestedId = "NestedId";
        mockObject.Nested.NestedName = "NestedName";

        Assert.AreEqual(mockObject.Id, mockObject.GetPropertyValue("Id"));
        Assert.AreEqual(mockObject.Name, mockObject.GetPropertyValue("Name"));
        Assert.AreEqual(mockObject.GetOnly, mockObject.GetPropertyValue("GetOnly"));
        Assert.AreEqual(mockObject.Nested.NestedId, mockObject.GetPropertyValue("Nested.NestedId"));
        Assert.AreEqual(mockObject.Nested.NestedName, mockObject.GetPropertyValue("Nested.NestedName"));

    }

    [Test]
    public void TestShouldSetPropertyValue()
    {
        MockClass mockObject = new MockClass();

        mockObject.SetPropertyValue("Id", "1");
        mockObject.SetPropertyValue("Name", "Name");
        mockObject.SetPropertyValue("Nested.NestedId", "NestedId");
        mockObject.SetPropertyValue("Nested.NestedName", "NestedName");

        Assert.AreEqual(mockObject.Id, "1");
        Assert.AreEqual(mockObject.Name, "Name");
        Assert.AreEqual(mockObject.Nested.NestedId, "NestedId");
        Assert.AreEqual(mockObject.Nested.NestedName, "NestedName");

    }
}

public static void ApplyPropertyChanges(this object objDest, object objToCopyFrom)
    {
        if (objDest == null)
            throw new ArgumentNullException();
        if (objToCopyFrom == null)
            throw new ArgumentNullException("objToCopyFrom");
        if (objDest.GetType() != objToCopyFrom.GetType())
            throw new Exception("Invalid type. Required: \"" + objDest.GetType().ToString() + "\"");

        foreach (System.Reflection.PropertyInfo piOrig in objDest.GetType().GetProperties())
        {
            object editedVal = objToCopyFrom.GetType().GetProperty(piOrig.Name).GetValue(objToCopyFrom, null);

            piOrig.SetValue(objDest,
            editedVal,
            null);
        }
    }

    public ActionResult Edit(Team editedTeamData)
    {
        if (!ModelState.IsValid)
            return View();

        Team origTeam = (from t in _db.Teams
                         where t.TeamID == editedTeamData.TeamID
                         select t).FirstOrDefault();

        origTeam.ApplyPropertyChanges(editedTeamData);
        _db.SubmitChanges();

        return RedirectToAction("Index");

    }