Using reflection to get values from properties from a list of a class

Question

I am trying to get the values from objects inside a list which is part of a main object.

I have the main object which contains various properties which can be collections.

Right now I am trying to figure out how to access a generic list which is contained in the object.

///<summary> ///Code for the inner class ///</summary> public class TheClass {     public TheClass();      string TheValue { get; set; } } //Note this class is used for serialization so it won't compile as-is  ///<summary> ///Code for the main class ///</summary> public class MainClass {     public MainClass();      public List<TheClass> TheList { get; set; }     public string SomeOtherProperty { get; set; }     public Class SomeOtherClass { get; set } }   public List<MainClass> CompareTheValue(List<object> MyObjects, string ValueToCompare) {      //I have the object deserialised as a list     var ObjectsToReturn = new List<MainClass>();     foreach(var mObject in MyObjects)     {          //Gets the properties         PropertyInfo piTheList = mObject.GetType().GetProperty("TheList");          object oTheList = piTheList.GetValue(MyObject, null);           //Now that I have the list object I extract the inner class          //and get the value of the property I want         PropertyInfo piTheValue = oTheList.PropertyType                                           .GetGenericArguments()[0]                                           .GetProperty("TheValue");          //get the TheValue out of the TheList and compare it for equality with         //ValueToCompare         //if it matches then add to a list to be returned          //Eventually I will write a Linq query to go through the list to do the comparison.         ObjectsToReturn.Add(objectsToReturn);      } return ObjectsToReturn; } 

I've tried to use a SetValue() with MyObject on this, but it errors out with (paraphrased):

object is not of type

private bool isCollection(PropertyInfo p) {     try     {         var t = p.PropertyType.GetGenericTypeDefinition();         return typeof(Collection<>).IsAssignableFrom(t) ||                typeof(Collection).IsAssignableFrom(t);     }     catch     {         return false;     }     } } 

Answer 1

To Get/Set using reflection you need an instance. To loop through the items in the list try this:

PropertyInfo piTheList = MyObject.GetType().GetProperty("TheList"); //Gets the properties  IList oTheList = piTheList.GetValue(MyObject, null) as IList;  //Now that I have the list object I extract the inner class and get the value of the property I want  PropertyInfo piTheValue = piTheList.PropertyType.GetGenericArguments()[0].GetProperty("TheValue");  foreach (var listItem in oTheList) {     object theValue = piTheValue.GetValue(listItem, null);     piTheValue.SetValue(listItem,"new",null);  // <-- set to an appropriate value }