Dynamically calling a method in C# ASP.NET

Question

I've seen users tackle this question before, like in thread: C# very dynamic invocation

But I haven't had much success with the code given. I'm basically trying to call a method using some variable string.

Here's what I have so far.

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class _Model : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

       string TargetMethod = "Index";
       Type t = System.Type.GetType("_Model");

       System.Reflection.MethodInfo methodInfo = t.GetMethod(TargetMethod);
       methodInfo.Invoke(t, new object[] {});

    }

     protected void Index(){
       Response.Write("Index: Dynamically called!"); 
     }

}

On the view page, I should see the string "Index: Dynamically called!" written to the screen but I'm getting error:

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Please help, thanks.

Marc Gravell · Accepted Answer · 2013-03-15 13:26:40Z

3

By default, GetMethod only returns public methods; add BindingFlags.NonPublic | BindingFlags.Instance and it should work.

var methodInfo = t.GetMethod(TargetMethod,
      BindingFlags.NonPublic | BindingFlags.Instance);

or to work for both public and non-public:

var methodInfo = t.GetMethod(TargetMethod,
      BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);

Also: it is an instance method, and you want to call it on the current instance, so:

methodInfo.Invoke(this, new object[] {});

Note the this, not t.

answered Mar 15, 2013 at 13:26

Marc Gravell

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6 Comments

Bennor McCarthy Over a year ago

Still won't work because the arguments to Invoke are wrong. Instead of t, it should be this.

hazzik Over a year ago

Also there is another error in his code. Should be methodInfo.Invoke(this, new object[] {});

Harvester316 Over a year ago

I added: System.Reflection.MethodInfo methodInfo = t.GetMethod(TargetMethod,BindingFlags.NonPublic | BindingFlags.Instance); but now I get error: CS0103: The name 'BindingFlags' does not exist in the current context

Marc Gravell Over a year ago

@Harvester316 so: resolve it like you would any other type. In this case, that is System.Reflection, so either add using System.Reflection; at the top, or explicitly use System.Reflection.BindingFlags. Also: just pressing ctrl+. will fix this for you automatically (giving you a choice of which approach to take)

Harvester316 Over a year ago

Thanks a lot Marc. It's alive and kicking. New to asp.net. I use notepad++, so ctrl+ won't work for me. By the way, not sure why my question got down rated. I guess I wasn't clear or too dumb for some people to be kind. Yikes. Thanks Marc!!

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