Setting Property Value

Question

I need to get and set a property value dynamically

I read this Get property value from string using reflection in C#

and did a below code for getting a value

public Object GetPropValue(Object obj, String name) {
    foreach (String part in name.Split('.')) {
        if (obj == null) { return null; }

        Type type = obj.GetType();
        PropertyInfo info = type.GetProperty(part);
        if (info == null) { return null; }

        obj = info.GetValue(obj, null);
    }
    return obj;
}

Now i need to set the value to other object which has a same property name

Employee emp1=new Employee();
var city=GetPropValue(emp1, "Address.City");

Need to set this city to other employee. Here Address is other class

emp1.GetType().GetProperty("Address.City").SetValue(emp2,city,null) //always sets null

But it is not setting. How can i make a generic setter method to make this job simple?

Answer 1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace LinqTests
{
    class Program
    {
        static void Main(string[] args)
        {
            var f1 = new F1 { F2 = new F2 { Name = "Test"}, Q = 10 };
            var f3 = new F3 { F2 = new F2() };
            Copier.Copy(f1, f3, "Q");
            Copier.Copy(f1, f3, "F2.Name");

        }

        static class Copier
        {
            public static void Copy(object source, object destination, string navigationPath)
            {
                var sourceValuePointHandle = GetValuePointHandle(source, navigationPath);
                var destinationValuePointHandle = GetValuePointHandle(destination, navigationPath);
                destinationValuePointHandle.SetValue(sourceValuePointHandle.GetValue());
            }

            private static ValuePointHandle GetValuePointHandle(object instance, string navigationPath)
            {
                var propertyName = new String(navigationPath.TakeWhile(x => x != '.').ToArray());
                var property = instance.GetType().GetProperty(propertyName);

                if (propertyName.Length != navigationPath.Length)
                {
                    var propertyInstance = property.GetValue(instance, null);
                    return GetValuePointHandle(propertyInstance, navigationPath.Substring(propertyName.Length + 1, navigationPath.Length - propertyName.Length - 1));
                }
                else
                    return new ValuePointHandle(instance, property);
            }

            class ValuePointHandle
            {
                public object Instance
                {
                    get;
                    private set;
                }

                public PropertyInfo Property
                {
                    get;
                    private set;
                }

                public ValuePointHandle(object instance, PropertyInfo property)
                {
                    Instance = instance;
                    Property = property;
                }

                public void SetValue(object value)
                {
                    Property.SetValue(Instance, value, null);
                }

                public object GetValue()
                {
                    return Property.GetValue(Instance, null);
                }
            }
        }

        class F1
        {
            public int Q
            {
                get;
                set;
            }

            public F2 F2
            {
                get;
                set;
            }
        }

        class F2
        {
            public string Name
            {
                get;
                set;
            }
        }

        class F3
        {
            public int Q
            {
                get;
                set;
            }

            public F2 F2
            {
                get;
                set;
            }
        }
    }

}

Answer 2

This line is not correct:

emp2.Address.City= emp1.GetType().GetProperty("Address.City").SetValue(emp2,city,null)

You're trying to set emp2.Address.City to the result of calling the setter of a property on a given object.

Why do you want to use reflection at all in this case? Given your line of code you can just write

emp2.Address.City = city;

as your reflection code is also setting the property of emp2. So even if it worked, it would do the same thing twice.

Your code would be like writing:

emp2.Address.City = city;
emp1.GetType().GetProperty("Address.City").SetValue(emp2,city,null);