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c# - 如何遍历类字段并设置属性

如何解决《c#-如何遍历类字段并设置属性》经验,为你挑选了4个好方法。

我不确定这是否可行但我想迭代一个类并设置一个字段成员属性而不显式引用字段对象:

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的答案中:

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

plinth.. 32

这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,以便您可以看到如何遍历属性信息对象.



1> plinth..:

这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,以便您可以看到如何遍历属性信息对象.



2> Konstantin T..:
public class Person
{
    public string Name { get; set; }
}

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

    public void DynamicallySetPersonProperty()
    {
        var p = GetType().GetField("person").GetValue(this);
        p.GetType().GetProperty("Name").SetValue(p, "new name", null);
    }
}


这不起作用.应该是`GetProperty`而不是`GetField`.

3> Paleta..:

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");

或设定

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

        private class TargetProperty
    {
        public object Target { get; set; }
        public PropertyInfo Property { get; set; }

        public bool IsValid { get { return Target != null && Property != null; } }
    }

    private static TargetProperty GetTargetProperty(object source, string propertyName)
    {
        if (!propertyName.Contains("."))
            return new TargetProperty { Target = source, Property = source.GetType().GetProperty(propertyName) };

        string[] propertyPath = propertyName.Split('.');

        var targetProperty = new TargetProperty();

        targetProperty.Target = source;
        targetProperty.Property = source.GetType().GetProperty(propertyPath[0]);

        for (int propertyIndex = 1; propertyIndex < propertyPath.Length; propertyIndex++)
        {
            propertyName = propertyPath[propertyIndex];
            if (!string.IsNullOrEmpty(propertyName))
            {
                targetProperty.Target = targetProperty.Property.GetValue(targetProperty.Target, null);
                targetProperty.Property = targetProperty.Target.GetType().GetProperty(propertyName);
            }
        }

        return targetProperty;
    }


    public static bool HasProperty(this object source, string propertyName)
    {
        return GetTargetProperty(source, propertyName).Property != null;
    }

    public static object GetPropertyValue(this object source, string propertyName)
    {
        var targetProperty = GetTargetProperty(source, propertyName);
        if (targetProperty.IsValid)
        {
            return targetProperty.Property.GetValue(targetProperty.Target, null);
        }
        return null;
    }

    public static void SetPropertyValue(this object source, string propertyName, object value)
    {
        var targetProperty = GetTargetProperty(source, propertyName);
        if(targetProperty.IsValid)
        {
            targetProperty.Property.SetValue(targetProperty.Target, value, null);
        }
    }

这里有几个测试

    [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");

    }
}

希望你觉得它有用.



4> David M..:

您正在尝试设置Employee类的_person字段的Name属性。它没有一个。尝试这个:

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

不知道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。

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