ASP.net MVC 5 call a js function from controller with a return already

Question

I am needing to be able to call a javascript function from my MVC 5 controller. However, I am currently using a return in my controller and from what I gathered, you are unable to return 2 things...

The code I currently have is this:

public async Task<FileResult> exportTempBom()
{
     bool x = await checkExcelFile();            
     string originalDirectory = Path.Combine(new DirectoryInfo(string.Format("{0}App_Data\\", Server.MapPath(@"\"))).ToString(), "downloads");
     byte[] fileBytes = System.IO.File.ReadAllBytes(originalDirectory + "\\BomTemp.xlsx");

     return File(fileBytes, "application/vnd.ms-excel", "BomTemplate.xlsx");
}

....more code here....

<iframe name="_frameDownload" id="_frameDownload" src="" style="width: 0px; height: 0px; display: none;"></iframe>

As you can see in the code above, I'm already sending back the excel file that the user has requested to download. However, I am needing to call a javascript function either before or after the return of the file to the user.

What I am needing to do is call loadingTheOverlay(false); from the controller AFTER the file has began to download. Calling this will take the overlay off of the page so that the user can continue to navigate the site.

The checkExcelFile() is where I check the excel file that they are about to download to make sure its up to date. If its not then it updates the file before it begins the download. That is why I am in need of the overlay so the user knows why its taking longer than normal to download the excel file.

I am calling that controller with this on the razor page:

 <ul class="dropdown-menu">
     <li>@Html.ActionLink("Download BOM Template", "exportTempBom", "Templates")</li>
     <li>@Html.ActionLink("Download Inventory Template", "exportTempInventory", "Templates", null, new {
        onclick = "loadingTheOverlay(true);",
        target = "_frameDownload"
   })</li>
 </ul>

Is there any MVC code that would do what the original ASP.net could do?

Page.ClientScript.RegisterStartupScript(this.GetType(),"CallMyFunction","MyFunction()",true);

@StealthRT did you try to use Javascript() method in controller action like following var script = "var a=2; var b=2; return"; var b = JavaScript(script); — hasan
– hasan, Commented Sep 20, 2017 at 13:15
@peggy Better explained in my OP what I am trying to accomplish. — StealthRT
– StealthRT, Commented Sep 20, 2017 at 13:16

Shyju · Accepted Answer · 2017-09-20 13:39:10Z

1

You can execute a javascript method before making the call to the action method.

You need to handle the click event on the link, prevent the default behavior, call your custom js function and then call the other action method.

@Html.ActionLink("Download BOM Template", "exportTempBom", "Templates",
                                                           null,new { id="downloadLink"})

The above code will render an anchor tag with id downloadLink.

Now the javascript to handle the click event of this specific link

$(function(){

   $("#downloadLink").click(function(e){
      e.preventDefault();
      myCustomMethod();
      window.location.href=$(this).attr("href");
   });      

});

You should not think about returning a javascript function/string literal for the js function from your server action method. That pattern is just bad!!!!

edited Sep 20, 2017 at 13:39

answered Sep 20, 2017 at 13:13

Shyju

220k106 gold badges420 silver badges499 bronze badges

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

7 Comments

StealthRT Over a year ago

The user does not click anything in the iframe. I do this so that I don't have to use something for the Target like "_Blank".

StealthRT Over a year ago

What I am needing to do is call loadingTheOverlay(false); from the controller AFTER the file has began to download.

Shyju Over a year ago

In your original question you said you want either before or after. There is no certain way for you to know when it actually began downloaded( what if the network was slow the it takes 30 seconds for the request to reach the server ? ). You can start the overlay when the user clicks the link.

StealthRT Over a year ago

The checkExcelFile() is where I check the excel file that they are about to download to make sure its up to date. If its not then it updates the file before it begins the download. That is why I am in need of the overlay so the user knows why its taking longer than normal to download the excel file.

Shyju Over a year ago

IMHO, I think showing a loading message when you download a file is unnecessary (download a file from gmail and see whether they show a loading message). I think you should better fix the code of the download method so that it if so much faster!

|

Collectives™ on Stack Overflow

ASP.net MVC 5 call a js function from controller with a return already

1 Answer 1

7 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

7 Comments

Your Answer

Sign up or log in

Post as a guest

Related