如何搜索T的嵌套属性以设置基类属性

Question

I have an XML serialiser that breaks when the XML returned isn't valid XML. So to combat this I wanted to display the error in the object returned rather than just null or break.

One of my classes is derived from a class that contains a string error property called message , it is this property I wish to set so that the error message can be seen.

Class structure could be two or three classes down. Using generic reflection, I wish to access the string property, message , of ClassC when I parse in either Class1 or ClassA.

Is it possible to access the Message property of ClassC? Currently when I send in an object that doesn't directly derive from ClassC it throws an exception because it cannot find the property (which doesn't exist in ClassA||1), however as not every class will be ClassA -> ClassB : ClassC , some could be Class1 -> Class2 -> Class3 : ClassC

Problem code: - I can only see the properties of the object parsed into the function, I need to be able to iterate through all of the properties, initialise if they are not already until I find the string property called message so I can set it and return an object containing useful error information.

var obj = (T)Activator.CreateInstance(typeof(T));
Type type = obj.GetType();
PropertyInfo prop = type.GetProperty("message");
prop.SetValue(obj, Convert.ChangeType(dirtyXml,prop.PropertyType), null);
return (T)obj;

Desired - for the message property within ClassC to be accessible to be set against. At present I need to initialise the other properties (that are classes), so ClassB or Class2 and Class3, before I can get to the message property. However I don't know which object will be passed into the function.

Two tier class structure:

Class ClassA 
{
    public ClassB classB { get; set; }
}

Class ClassB : ClassC 
{
    // other properties 
}

Class ClassC 
{
    public String message { get; set; }
{

Answer 1

I think you don't really want to find a randomly-typed object with a message property - you specifically want to find an object derived from ClassC . So you'd be better with something like this, which looks down the hierarchy of properties until it finds something derived from ClassC :

using System;

public class Program
{
    class ClassA
    {
        public ClassB classB { get; set; }
    }

    class ClassB : ClassC
    {
    }

    class ClassC
    {
        public string message { get; set; }
    }

    static T FindClass<T>(object obj) where T : class
    {
        var classType = obj.GetType();
        var targetType = typeof(T);

        if (IsDerivedFrom(classType, targetType))
        {
            return (T)obj;
        }

        foreach (var prop in classType.GetProperties())
        {
            if ( prop.PropertyType.IsClass)
            {
                var childObj = prop.GetValue(obj);

                var target = FindClass<T>(childObj);
                if (target != null)
                {
                    return target;
                }
            }
        }

        return null;
    }

    static bool IsDerivedFrom(Type class1, Type class2)
    {
        return class2.IsAssignableFrom(class1);
    }

    public static void Main()
    {
        var classA = new ClassA { classB = new ClassB() };
        classA.classB.message = "Hello";

        var classC = FindClass<ClassC>(classA);

        if (classC != null)
        {
            Console.WriteLine(classC.message);
        }
    }
}

(Take a look at this fiddle to see it in action).