Question

83

Programmatically set Request[__EVENTTARGET] from javascript

rated 0 times [ 87] [ 4] / answers: 1 / hits: 9608 / 11 Years ago, tue, december 3, 2013, 12:00:00

I'm writing ASP.NET application, and I should check on server-side value of Request[__EVENTTARGET] in Page_Load. I need to set it value from client-side programmically.
I try to set it by this:

document.getElementById('__EVENTTARGET').value = my_value;

but it doesn't work. Can you help me, why? Thank you!

UPD:

function ShowUploadDialog(obj) {

            document.getElementById('<%= uplReportLogo.ClientID %>').click();

            document.getElementById('<%= hdnInvokeFileUpload.ClientID %>').value = $('input[type=file]').val();

            __doPostBack(obj.id, 'Click');

}

Server controls:

<asp:FileUpload runat=server ID=uplReportLogo CssClass=file upload />

<asp:Button runat=server ID=btnReportImage Text=Load Image... CssClass=button action load 

     OnClientClick=javascript: return ShowUploadDialog(event, this); OnClick=btnReportImage_Click />

UPD2:

function __doPostBack(eventTarget, eventArgument) {

    if (!theForm.onsubmit || (theForm.onsubmit() != false)) {

        theForm.__EVENTTARGET.value = eventTarget;

        theForm.__EVENTARGUMENT.value = eventArgument;

        theForm.submit();

    }

}

I have Access denied exception on row theForm.submit(); Why?

Answers

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adriannemyiag

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3 Years ago

answered 11 Years ago alli · Accepted Answer

That variable is used by ASP.NET to store the sender of any postback, so I think your value is getting overwritten each time.
You may try to invoke

__doPostBack('my_value','any_other_argument')

by JS, then checking such value in Page_Load event.

For this to work, be sure to remove EventValidation attribute in the first line of your ASPX file.

This is how you can handle it on code-behind:

    protected void Page_Load(object sender, EventArgs e)

    {

        if (IsPostBack)

        {

            string _evt = this.Request[__EVENTTARGET]; // 1st parameter

            string _eva = this.Request[__EVENTARGUMENT]; // 2nd parameter

            switch (_evt)

            {

                case my_value:

                    //do anything here

                    break;

                default:

                    break;

            }

        }

    }

EDIT:

Edited to follow your example:

JS:

function ShowUploadDialog() {

        document.getElementById('<%= uplReportLogo.ClientID %>').click();

        document.getElementById('<%= hdnInvokeFileUpload.ClientID %>').value = $('input[type=file]').val();

        __doPostBack('fileUpload', '');

    }

ASPX:

<asp:Button runat=server ID=btnReportImage Text=Load Image... CssClass=button action load 

        OnClientClick=ShowUploadDialog();  />

CS:

protected void Page_Load(object sender, EventArgs e)

{

    if (IsPostBack)

    {

        string _evt = this.Request[__EVENTTARGET]; // 1st parameter

        string _eva = this.Request[__EVENTARGUMENT]; // 2nd parameter

        switch (_evt)

        {

            case fileUpload:

                btnReportImage_Click(); 

                break;

            default:

                break;

        }

    }

}



protected void btnReportImage_Click() // remove sender & event arguments here, you do not need them

{

    //your code

}