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genericsreflectionc#-4.0collectionsintrospection

setting scalar value on collection using introspection


I am doing something like the answer on: Set object property using reflection

Dynamically setting the value of a object property. I have a function wrapping this sort of functionality and it works great. However, I want to make it so that it looks at the property type to see if it is some sort of collection and add the value/object to the collection.

I tried to do something like: if (object is ICollection) The problem is that VS2010 wants me to type the collection which I dont know how to do programatically.

So what I want to do is something like the following given subject is the target object and value is value to be set:

public void setPropertyOnObject(object subject, string Name, object value)
{
  var property = subject.GetType().GetProperty(Name)
  // -- if property is collection ??
  var collection = property.GetValue(subject, null);
  collection.add(value)
  // -- if propert is not a collection
  property.SetValue(subject, value, null);
}

Solution

  • You can dynamically check a typed collection (and add an item to it) thusly:

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Reflection;
    using System.Text;
    
    namespace ConsoleApplication1
    {
        class Program
        {
            static void Main(string[] args)
            {
                Object subject = new HasList();
                Object value = "Woop";
                PropertyInfo property = subject.GetType().GetProperty("MyList", BindingFlags.GetProperty | BindingFlags.Instance | BindingFlags.Public);
                var genericType = typeof (ICollection<>).MakeGenericType(new[] {value.GetType()});
                if (genericType.IsAssignableFrom(property.PropertyType))
                    genericType.GetMethod("Add").Invoke(property.GetValue(subject, null), new[] { value });
            }
        }
    
        internal class HasList
        {
            public List<String> MyList { get; private set; }
            public HasList()
            {
                MyList = new List<string>();
            }
        }
    }