read html attributes in asp.net

Question

I have a hidden variable in my aspx page as below.

  <input type="hidden" value="" runat="server" id="homeExcelData" filename=""/>

On click of a button, iam doing a a form.Sumbit();

Before submitting, i am setting the properties of the hidden control as below.

document.getElementById("homeExcelData").attributes["filename"] = "test.xls";
                            $("#homeExcelData").attr("filename","test.xls");
                            $("#homeExcelData").prop("filename","test.xls");
                            alert($("#homeExcelData").attr("filename"));
                            $("#homeExcelData").val(excelData);

In the code behind, during postback, i can get the excelData by homeExcelData.Value which i set in the javascript.

But the value of the attribute "filename" is coming as empty string(not as null) instead of "test.xls".

Please help me to fix it.

Server side code:

 string fileName = homeExcelData.Attributes["filename"] ?? "report.xls";

Values will be lost when postpack. So you should keep values in ViewState. — Sinan AKYAZICI
– Sinan AKYAZICI, Commented Mar 12, 2012 at 9:49

jbl · Accepted Answer · 2012-03-12 10:00:50Z

2

Why do you think the filename attribute value should be part of the POST request to the server ?

( It will only be part of the viewstate value if you set it server-side )

I would have another hidden field "homeExcelDataFileName" and use its value.

Hope this will help,

answered Mar 12, 2012 at 10:00

jbl

15.5k3 gold badges37 silver badges104 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Raghav Over a year ago

Thats right. But when the form.Submit() is done, the view state is refreshed & reconstructed in the aspx page and submitted back to server. If your adding a value to the control via js, it comes to the server as control.Value. Which means that for certain HTML attributes, the viewstate is reconstructed fine. But for custom HTML attributes, the viewstate is not refreshed. So basically i need a some trick to make asp.net read the custom attributes and pack it into the viewstate of the control. then it would come automatically to server.

Raghav Over a year ago

Its not just file name, i need to add a few more custom attributes. May be i need to recontruct my value as a complex json wit these attributes.

jbl Over a year ago

The viewstate should never be modified or reconstructed client-side. As far as I know, submit() does not alter the view state before issuing the post request. ViewStateMac is here to help check that ("Invalid ViewState"). You may use some js to gather, encode and "pack" your data in some hidden field which value will be decrypted server side to alter your controls features.

Zo Has · Accepted Answer · 2012-03-12 09:31:34Z

1

The above works for me. I think what is happening is that on postback of your submit button the value is somehow getting re initialized (Your javascript for adding attributes is loading twice-moving it to server side works for me)

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        // Set attribute on page Load
        homeExcelData.Attributes.Add("filename","test.xls");
    }
}

protected void btnCheckValues_Click(object sender, EventArgs e)
{
    Response.Write( homeExcelData.Attributes["filename"].ToString());

}

answered Mar 12, 2012 at 9:31

Zo Has

13.1k24 gold badges92 silver badges150 bronze badges

2 Comments

Raghav Over a year ago

If we are adding it in code-behind, then it works fine. the problem occurs if we add it in javascript and did a from.Sumbit() instead of button_click

Zo Has Over a year ago

I think adding an attibute & value client side might not get rendered on page so it is turning out empty.

Collectives™ on Stack Overflow

read html attributes in asp.net

2 Answers 2

3 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related