How to use the onClick event for Hyperlink using C# code?

Question

I am trying to add a condition for a hyperlink that I have in my page.

Instead of just using a particular link like: <a href="help/Tutorial.html">Tutorial</a> I want to display different pages for different users. For example, if the user is logged in as Admin, they will be presented with different link than regular users.

I have modified my hyperlink as: <a onclick="displayTutorial_Click">Tutorial</a>

and added this code:

    protected void displayTutorial_Click(object sender, EventArgs e)
    {
        // figure out user information
        userinfo = (UserInfo)Session["UserInfo"];

        if (userinfo.user == "Admin")

            System.Diagnostics.Process.Start("help/AdminTutorial.html");

        else

            System.Diagnostics.Process.Start("help/UserTutorial.html");            
    }

But this didn't work. Can anyone please help me to figure out how I can make the Tutorial link work properly? Thank you a lot in advance!!!

Jeremy Wiggins · Accepted Answer · 2013-09-17 16:34:08Z

16

The onclick attribute on your anchor tag is going to call a client-side function. (This is what you would use if you wanted to call a javascript function when the link is clicked.)

What you want is a server-side control, like the LinkButton:

<asp:LinkButton ID="lnkTutorial" runat="server" Text="Tutorial" OnClick="displayTutorial_Click"/>

This has an OnClick attribute that will call the method in your code behind.

Looking further into your code, it looks like you're just trying to open a different tutorial based on access level of the user. You don't need an event handler for this at all. A far better approach would be to just set the end point of your LinkButton control in the code behind.

protected void Page_Load(object sender, EventArgs e)
{
    userinfo = (UserInfo)Session["UserInfo"];

    if (userinfo.user == "Admin")
    {
        lnkTutorial.PostBackUrl = "help/AdminTutorial.html";
    }
    else
    {
        lnkTutorial.PostBackUrl = "help/UserTutorial.html";
    }
}

Really, it would be best to check that you actually have a user first.

protected void Page_Load(object sender, EventArgs e)
{
    if (Session["UserInfo"] != null && ((UserInfo)Session["UserInfo"]).user == "Admin")
    {
        lnkTutorial.PostBackUrl = "help/AdminTutorial.html";
    }
    else
    {
        lnkTutorial.PostBackUrl = "help/UserTutorial.html";
    }
}

edited Sep 17, 2013 at 16:34

answered Jan 9, 2012 at 6:22

Jeremy Wiggins

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2 Comments

AlwaysANovice Over a year ago

Thank you Jeremy for your elaborated answer! however, when I am trying the exact thing, I am getting this error message: "The name 'lnkTutorial' does not exist in the current context" even after adding the ID for the asp:HyperLink. any idea why?

RSW Over a year ago

@Jeremy I can't find an OnClick event for the HyperLink control...were you possibly thinking of LinkButton?

pushkin · Accepted Answer · 2020-09-14 18:15:54Z

5

Wow, you have a huge misunderstanding how asp.net works.

This line of code

System.Diagnostics.Process.Start("help/AdminTutorial.html");

Will not redirect a admin user to a new site, but start a new process on the server (usually a browser, IE) and load the site. That is for sure not what you want.

A very easy solution would be to change the href attribute of the link in you page_load method.

Your aspx code:

<a href="#" runat="server" id="myLink">Tutorial</a>

Your codebehind / cs code of page_load:

...
if (userinfo.user == "Admin")
{
  myLink.Attributes["href"] = "help/AdminTutorial.html";
}
else 
{
  myLink.Attributes["href"] = "help/otherSite.html";
}
...

Don't forget to check the Admin rights again on "AdminTutorial.html" to "prevent" hacking.

edited Sep 14, 2020 at 18:15

pushkin

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answered Jan 9, 2012 at 6:27

Grrbrr404

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1 Comment

Grrbrr404 Over a year ago

Please check answer of Jeremy Wiggins if you want to use the Server Control "HyperLink"

prema · Accepted Answer · 2012-01-09 06:21:31Z

1

this may help you.

In .cs page,

//Declare a string
   public string usertypeurl = "";
  //check who is the user
       //place your code to check who is the user
       //if it is admin
       usertypeurl = "help/AdminTutorial.html";
       //if it is other 
        usertypeurl = "help/UserTutorial.html";

In .aspx age pass this variabe

  <a href='<%=usertypeurl%>'>Tutorial</a>

answered Jan 9, 2012 at 6:21

prema

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