Get property of object property by string in C#

Question

How to access to property of property in object instance using string ? I would like automate changes i will made in form for example responding to object below:

class myObject{
   Vector3 position;
   public myObject(){
       this.position = new Vector3( 1d,2d,3d);
   }
};

Form have eg three numericUpDown called respectively position_X , position_Y , position_Z ; Instead having three callbacks for events as:

private void positionX_ValueChanged(object sender, EventArgs e)
  { 
    // this.model return myObject
    this.model().position.X = (double)  ((NumericUpDown)sender).Value;

  }

I would have one callback which can automatically set particular attribute in model from control name/tag

Below is javascript which describe purpose i want :)

position_Changed( sender ){
   var prop = sender.Tag.split('_'); ; // sender.Tag = 'position_X';      
   this.model[ prop[0] ] [ prop[1] ] = sender.Value;
}

Answer 1

You can use either reflection or expression trees to do that.

The simple reflection way (not very fast but versatile):

object model = this.model();
object position = model.GetType().GetProperty("position").GetValue(model);
position.GetType().GetProperty("X").SetValue(position, ((NumericUpDown)sender).Value);

Note: if Vector3 is a struct you may not get the expected results (but that has to do with structs and boxing, not with the code per se).

Answer 2

To complement the previous answer, which is essentially what you're looking for:

object model = this.model();
object position = model.GetType().GetProperty("position").GetGetMethod().Invoke(model, null);
var propName = (string) ((NumericUpDown)sender).Tag;
position.GetType().GetProperty(propName).GetSetMethod().Invoke(model, new [] {((NumericUpDown)sender).Value});

That is, you could just use the Tag property of Control to specify to which property of your Vector3 object the NumericUpDown instance is "bound" to.