Response.Write and UpdatePanel

Question

I generate a vcard that I send to the client using the following code snippet:

Response.AddHeader("Content-Disposition", string.Format("attachment; filename={0}", fileNameOnly));
Response.ContentType = "text/x-vcard";
Response.ContentEncoding = Encoding.GetEncoding("ISO-8859-1");
Response.Write(vCard.ToString());
Response.End();

However, I need to use vCards on a page that has the control inside and UpdatePanel. Unfortunately, according to Update panel and Response write this does not work and causes an error. I am wondering what are some alternative ways to send the contents of the vcard/file to the client's browser and have it display "open/save" dialog that don't involve Response.Write?

Only if you make update panel to cancel the ajax update and make full post of hole page. Other way is to use a handler to send your x-vcard and this is better from all cases. — Aristos, Apr 04 '12 at 16:04

score 40 · Accepted Answer · answered Apr 04 '12 at 16:15

40

You can't use Response.Write during an asynchronous postback. Whatever control executes that code needs to be added as a PostBackTrigger in the update panel:

<Triggers>        
    <asp:PostBackTrigger ControlID="Button1" />
</Triggers>

You can also do it in code-behind, if you prefer:

ScriptManager.GetCurrent().RegisterPostBackControl(Button1);

answered Apr 04 '12 at 16:15

James Johnson

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GetCurrent() should receive one argument probably a this will work – Gabriel Monteiro Nepomuceno Sep 30 '14 at 21:20
This didn't work for me, but I'm using updatepanels alongside a modalpopupextender and I'm wondering if that is an additional problem. I'm just trying to do a regular file download off of the server. – JoeManiaci Feb 16 '16 at 18:55
Works Great. Add the PostBackTrigger alongside AsyncPostBackTrigger triggers such as combobox on change events: – RBILLC Mar 18 '19 at 16:09
Check the Edited answer now it works totally fine ..tried and tested – BKM Nov 11 '19 at 06:58

Pankaj · Answer 2 · 2012-04-04T18:55:22.100

1

Response.Write will not work under Asynchronous Events. My suggestion is to remove the Update Panel in case it is specifically being used for VCard point of view only.

Alternatively - Place a control inside the Update Panel and initialize it's value under asynchronous event. Now it will work.

edited Apr 04 '12 at 18:55

answered Apr 04 '12 at 18:49

Pankaj

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score 1 · Answer 3 · answered Sep 26 '12 at 10:09

1

Why don't you consider the use of a separate handler/page to serve the vcard?

This is maybe the easiest and cleaner way to do that and it doesnt interfere any other (async or not) postback related to the updatepanel.

answered Sep 26 '12 at 10:09

Alex Pollan

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score 1 · Answer 4 · edited Mar 22 '16 at 00:30

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I had a similar problem with Response.Write. I found a workaround or maybe even a solution to this problem. Capture the TextWriter given to the RenderBeginTag of a server control and write to that.

I blogged with an example here: http://timscyclingblog.wordpress.com/2013/03/07/asp-net-web-forms-response-write-in-an-updatepanel-dev-web/

edited Mar 22 '16 at 00:30

CaringDev

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answered Mar 07 '13 at 22:11

user2000095-tim

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This is technically an answer to the question, but it landed in LQP so it's liable to get deleted by trigger-happy reviewers. Consider including some of your blog post in this answer. – Jeffrey Bosboom Mar 21 '16 at 21:25

Response.Write and UpdatePanel

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