Unhelpful error on RegisterClientScriptBlock

Question

I am using RegisterClientScriptBlock to send a JS alert to the user when the users goes into edit mode on a gridview, but it causes my page to error for some reason and I can't figure out why...

This is the method that causes the problem. The error occurs in the last line where the script is registered. (If I comment this out the page works fine!)

    protected void EditRecord(object sender, GridViewEditEventArgs e)
    {

        gvStockItems.EditIndex = e.NewEditIndex;
        // Gather current Search info
        string strPartNo = Session["currentSearchTerm"].ToString();
        BindData();
        gvStockItems.SelectedIndex = gvStockItems.EditIndex;
        Page.ClientScript.RegisterClientScriptBlock(typeof(Page), "thisIsTest", "<script language=\"text/javascript\">alert(\"oops\");</script>");
    }

The error that is thrown in the JS console is

Uncaught Sys.WebForms.PageRequestManagerServerErrorException: Sys.WebForms.PageRequestManagerServerErrorException: Object reference not set to an instance of an object.

It also says that this error occurred in Error$Create in the ScriptResource.axd, but I think this is an error that occurs on reporting what the real issue is, so I'm completely stumped.

Any help is greatly appreciated. Thanks.

My guess is it's this: `typeof(Page)`. Try changing it to `this.GetType()` — CAbbott, Jun 19 '12 at 14:07
That's why it was a guess. :) Have you tried debugging to check that `Page` & `ClientScript` are objects? Otherwise I'm stumped as well. — CAbbott, Jun 19 '12 at 14:16
No worries, thanks for your help. I think the issue I'm having is that the error message and the break is not at the actual error, it's on the reporting of the error... — Ben Drury, Jun 19 '12 at 14:19
Yes, a grid view within an update panel. I have found a clash with something else in web.config, which was causing that error message. Now it doesn't error, but it also does not display the alert. — Ben Drury, Jun 19 '12 at 14:25
Have a look at this: http://stackoverflow.com/a/239674/113763 — CAbbott, Jun 19 '12 at 14:26
Thanks will work through some of those and try to find the real problem. — Ben Drury, Jun 19 '12 at 14:34

Damith · Answer 1 · 2012-06-19T15:40:55.083

remove Page.ClientScript.RegisterClientScriptBlock and try using RegisterStartupScript

// Define the name and type of the client scripts on the page.
String csname1 = "thisIsTest";
Type cstype = this.GetType();

// Get a ClientScriptManager reference from the Page class.
ClientScriptManager cs = Page.ClientScript;

// Check to see if the startup script is already registered.
if (!cs.IsStartupScriptRegistered(cstype, csname1))
{
    StringBuilder cstext1 = new StringBuilder();
    cstext1.Append("<script type=text/javascript> alert('oops!') </");
    cstext1.Append("script>");

    cs.RegisterStartupScript(cstype, csname1, cstext1.ToString());
}

OR if you have ScriptManager then

ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "thisIsTest", "alert('oops!');", true);

score 1 · Answer 2 · edited Jun 19 '12 at 15:34

1

It appears to be to do with call registering scripts from code behind when doing only partial update within an update panel. If I set EnablePartialRendering="false" in the script manager it all works fine. Where as if I allow partial rendering the error occurs.

edited Jun 19 '12 at 15:34

Damith

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answered Jun 19 '12 at 14:45

Ben Drury

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You can add the 4th parameter to RegisterStartupScript (make it True) and avoid adding messy ` – Yuriy Galanter Jun 19 '12 at 15:47

Unhelpful error on RegisterClientScriptBlock

2 Answers2