I have a large excel document that is generated when the user clicks on the download link. When the download link is clicked the browser pops up the standard open save cancel dialog. The problem is that the wait time can be really long e.g. 15 seconds or more before the dialog appears. I want to show a busy gif while the request is in progress. How can I accomplish this?
I'm pretty sure I can show a gif easily using jQuery, but I'm not sure how to stop/hide the busy indicator when the new document (excel doc) has finished loading. Is there a javascript event that I could attach a handler to?
Another option is the temporary file method: Is there a way to detect the start of a download in JavaScript?
Basically:
User clicks on download link/button
An AJAX request is sent to create the excel doc. Show the 'busy' indicator.
The excel doc is created and saved to a temporary file on the server. A response is sent containing a unique id that identifies the file.
The AJAX response is handled on the client-side. Hide the 'busy' indicator. window.location is changed to something like 'download.aspx?id=###' which prompts the user to save the file.
The problem here is that clicking the link fires off another request which is nothing to do with the first one. You could have the code that handles the download request update some kind of session data, which a bit of Ajax on the linking page then polls to determine when the request handler is in the process of offering up the data for download.
Alternatively, you could simply make it time out after a reasonable period of time, say 30 seconds, and perhaps offer up an explanation. This might then transition through a couple of states:
"Click here to download the super-duper PDF of awesomeness!"
"Please wait, generating a whole dollop of fonty goodness..."
"It may take some time to bundle all that uber-data into a download...if nothing's happening, maybe you want to try again?"
This seems to be the approach Google Mail takes when it comes to detecting timeouts or similar problems.
Related
I have a form that dynamically generates a PDF based on database data. But I don't want to navigate away from the form whilst the PDF is generated and downloaded. So I am using response.redirect to call the .aspx page that generates the PDF and serves it via stream (Have done for many years) so there may be a better option out there now. However I have found people are logging out before the PDF has been sent to the browser which is causing issues.
Is there a way to detect when the reponse.redirect has finished and the file has been downloaded?
I have tried using postmessage and a listener but this doesn't work.
I've also tried setting up and EndRequestHandler as below in my main form:
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler) ;
But this hasn't worked either. The browser is aware as as the tab with the main form has a progress icon in, so there must be a way to intercept the complete event.
Might not be accurate like you want it but I do something sort of similar. When the button is clicked, a "Please Wait..." message appear until the file is ready to be downloaded. The way I do it is the client wait for a cookie. When the server is ready to send the file (after processing) it sets a cookie. Even if the cookie was set in a different request, the client still gets the updated value.
On my page I have a button to download a document.
I am building the page with steps, so step 1 is choosing a type, step 2 is downloading the document and step 3 is to write some information in a textbox.
What I would like to do is to show step 3 after the button for the download has been pressed.
So in the button_click event I first put some code to show step 3 and then I need to do something to download the form.
To download the document I use a ASHX handler file. That works fine.
But my problem is that when I go to that handler, my page is not updated.
I used
response.redirect("GiveFile.ashx?file=document.doc",false)
After some reading I found that using response.redirect ends the current response so the page is not updated.
I was thinking of creating a new response and redirect that one to the handler file, but I can't find an example to see how that is done. I also don't know if it will work.
I also tried
server.transferrequest("GiveFile.ashx?file=document.doc",true)
but that also ends the current response.
Who can help me with this?
rg,
Eric
Google is using a hidden iframe to download files 'in the background'.
Check this article with code sample:
http://encosia.com/ajax-file-downloads-and-iframes/
I have a performance issue where we have a 2 page setup as part of a workflow in a bigger system. This section is dedicated to rendering reports allowing users to chose their own parameters.
Page1.aspx collects parameter information for a report. It takes the information submitted on a form and validates it. If it validates OK, it stores the selections in the DB as XML, then redirects to Page2.aspx with the run id in the query string. Simple enough, performance is great.
Page2.aspx pulls the ID out of the DB and hydrates a Crystal ReportDocument object (taking milliseconds) then we call ExportToHttpStream which then renders the report as a PDF or DOC or XLS download (output format is determined in Page1.aspx). The performance of the ExportToHttpStream method is very poor due to the way our reports are written and DB indexes on the target system. This is outwith my control at the moment but I am promised that they are being worked on.
So the problem is, that when the submit button in Page1.aspx is pressed, the user experiences a very long delay before the download starts. It is then compounded by the user pressing the submit button again thinking there is a problem.
I think what I need to do is have Page1.aspx redirect to Page2.aspx. Page2.aspx should render the master page furniture and a loading div, and the report should render asynchronously somehow in the background before the save dialogue automatically pops up, after this i'd like to change the loading div to a 'Report generated, click here to go back'.
If this is the best way to achieve this, how can I load a full page, then request the report asynchronously? I'm open to any suggestions here.
You could use ajax to load the report on Page2.aspx and show a loading message while it's processing.
Look at the jQuery.load() method. This might be the easiest way to accomplish what you are trying to do.
Page1.aspx - collect parameters
Page2.aspx - report view, calls Page2Details.aspx via ajax.
Try loading Page2.aspx inside iframe and use jQuery to display waiting indicator and hide it after Page2.aspx download
Whilst both answers gave me some ground to go out and research in the right direction. My solution included using the fileDownload plugin from John Culviner to facilitate a similar solution:
jQuery fileDownload by John Culviner
This allowed me the following page structure:
Page1.aspx, gathers and validates parameters for the report and puts them into Oracle.
Page2.aspx, whilst passed in the runid (pointer to the parameters in the db) via the query string setup 3 hidden divs. Loading, Error and Success.
The script mentioned above was employed at this point. jQuery firstly sets the loading div visible then calls the plugin. The plugin dynamically creates an iframe and downloads the binary (xls/doc/pdf) from Page3.aspx. It then fires a success callback or failure. The success callback is fired by means of a cookie set at the end of the response in Page3.aspx.
I believe the plugin mentioned downloads using a 'text/plain' AJAX call in jQuery avoiding the limitation of there not being an octet-stream equivalent in AJAX.
It works, its not the cleanest solution by any means, it doesn't degrade one bit, but provides the users on our controlled intranet with an extremely responsive and pleasing UI.
I got a part on my page I want to improve. It's a file upload that users can add their contacts from files like excel, csv & outlook. I read the contacts and place them in the database, so what I would like to do is to have a regular icon that spins while that operation is doing that, how could I do that? Ajax? I don't want progress bar for the file upload but the operation for reading the file
EDIT: I want to know how to make this work with the add to database using ajax. like should I use a updatepanel? how I could combine a ajax callback with the spinning icon
Thanks
You can generate your own spinning icon on www.ajaxload.info. If you combine it with the jQuery BlockUI plugin, you can display your own modal wait screen.
Spin a GIF.
http://www.ajaxload.info/
If you are using the asp:fileupload, there is a couple things that you can do.
Take advantage of the fact that the asp:fileupload takes a bit of time to upload the file and that is also performs a post-back.
1) put a client-side onclick event for the 'upload' button that will display your spinny graphic and give a message saying 'file being parsed and added to database'.
2) put the server-side onclick event for the 'upload' button that will upload the file, parse it and insert records into the database.
3) when the server-side onclick finishes, the remainder of the page lifecycle occurs and the user gets a fresh page returned to them. And when the browser receives the new page, the spinny graphic will no longer be visible.
This won't allow you to change the message during the upload, but it is quick and easy.
The alternative would be to look at jquery and do some ajax calls.
In my ASP.Net application I have a requirement that when a user clicks on an UI element we generate a PDF for them which they can download. This is currently implemented by doing a form post to an ashx page. This page essentially inspects the form and then executes the correct server side page which either results in HTML or a PDF document of that pages HTML.
On the client I know ahead of time if we are going to be getting a PDF or HTML, when its an HTML I open a new window and direct the form post to that window and all works well. When its a PDF I don't change the target for the form and it remains on the current page.
This works, the user is presented with a save dialog, and the current page is not changed or lost.
The problem I have is that generating the PDF takes anywhere from 1-15 seconds. What I want to do is popup a please wait dialog. Displaying the popup is going to be easy, what I am not sure of is how do I know to close the popup? The popup will be a div in the current page.
The popup can have a client side timer which polls the server for task completion. The long running server task should update the progress in a database table or a server cache object which can be accessed by the polling service.
Couple of old articles from MSDN magazine. You should be able to use the same concepts with newer libraries like asp.net Ajax.
Reporting Task Progress With ASP.NET 2.0
Simplify Task Progress with ASP.NET "Atlas"
just have some javascript on the client side and let it show some animated GIF for 1-15 seconds (your choice) and close itself after the designated time.
Gulzar's suggestion was spot on. I have a simple ajax enabled wcf service which checks a session variable. My ashx page sets the variable to false when it starts processing and then true when its done.
I think there might be a race condition if the client checks before we set the session item to false; however, there are ways around that if we modify the service to set the session item to false after a client gets an im done response.
The tricks is still going to be figuring out what the intervalon the client should be. If we set it to low the user could save the file and then see the still processing message. I'm debating myself between half a second and a second. Anything less then a half a second seems unnessecary.
You said:
When its a PDF I don't change the
target for the form and it remains on
the current page.
If that is the case then the original page will be gone when the PDF is opened. In that situation I would have a loading animated gif and open it using Javascript into a div tag overlaying the rest of the page. You would not need to close it, so no timer or polling needed. It would just be gone when the page is gone.