Convert to a Type on the fly in C#.NET

Question

Alternative Title: Dynamically convert to a type at runtime.

I want to to convert an Object to a type that will be assigned at runtime.

For example, assume that I have a function that assigns a string value(from a TextBox or Dropdownlist) to an Object.Property.

How would I convert the value to proper type? For instance, it could be an integer, string, or enum.

Public void Foo(object obj,string propertyName,object value) {   //Getting type of the property og object.   Type t= obj.GetType().GetProperty(propName).PropertyType;    //Now Setting the property to the value .   //But it raise an error,because sometimes type is int and value is "2"   //or type is enum (e.a: Gender.Male) and value is "Male"   //Suppose that always the cast is valid("2" can be converted to int 2)    obj.GetType().GetProperty(propName).SetValue(obj, value, null); } 

Answer 1

You need to use the Convert.ChangeType(...) function [note: in the function below, the input propertyValue could just as easily have been of type object ... I just had a string version pre-baked]:

/// <summary> /// Sets a value in an object, used to hide all the logic that goes into ///     handling this sort of thing, so that is works elegantly in a single line. /// </summary> /// <param name="target"></param> /// <param name="propertyName"></param> /// <param name="propertyValue"></param> public static void SetPropertyValueFromString(this object target,                                              string propertyName, string propertyValue) {     PropertyInfo oProp = target.GetType().GetProperty(propertyName);     Type tProp = oProp.PropertyType;      //Nullable properties have to be treated differently, since we      //  use their underlying property to set the value in the object     if (tProp.IsGenericType         && tProp.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))     {         //if it's null, just set the value from the reserved word null, and return         if (propertyValue == null)         {             oProp.SetValue(target, null, null);             return;         }          //Get the underlying type property instead of the nullable generic         tProp = new NullableConverter(oProp.PropertyType).UnderlyingType;     }      //use the converter to get the correct value     oProp.SetValue(target, Convert.ChangeType(propertyValue, tProp), null); }