Blazor Server App - Downlaod files from server

Question

Could you please let us know to download pdf/excel file from server location to client without using javascript?

Answer 1

Hi @Anantham.S ,

Actually, it is same as downloading a file in a razor page app. You can implement it with the below steps:

1. Add a link to the page: <a class="form-control btn btn-primary" href="/download">Download</a>
2. Add a razor page to the Pages folder, name it like "Download"

Download.cshtml:

@page "/download"  

@model Namespace.DownloadModel  

Download.cshtml.cs:

    public class DownloadModel : PageModel  
    {  
        private readonly IWebHostEnvironment _env;  

        public DownloadModel(IWebHostEnvironment env)  
        {  
            _env = env;  
        }  

        public IActionResult OnGet()  
        {  
            var filePath = Path.Combine(_env.WebRootPath, "files", "file1.xlsx");  

            byte[] fileBytes = System.IO.File.ReadAllBytes(filePath);  

            return File(fileBytes, "application/force-download", "file1.xlsx");  
        }  
    }  

Result:

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Best Regards,

Jiadong Meng

Answer 2

Hi @Mario The following example illustrates how to receive a parameter from the page

@page "{file?}"  
  
@functions {  
         public IActionResult OnGet(string file)  
         {  
              if(string.IsNullOrEmpty(file)  
                  return NotFound();  
  
               byte[] fileBytes = System.IO.File.ReadAllBytes("path-to-dir\" + file);  
               return File(fileBytes, "application/force-download", file);  
         }  
}  

<a href="/download/file.zip">download</a>

Answer 3

Could you give me a hint on how to access routing variables in this example? i.e. I access URL/download/Filename.txt

How woudl I go about retrieving the string "Filename.txt"? In Razor/Blazor normally it's done with routing variables, by declaring

@Anonymous "/download/{myvar}" and then declaring / accessing a [Parameter]string Myvar in the code. Obviously this doesn't work (out of the box ) with your code, but I am a bloody beginner in the Razor / Blazor world, and have no idea what to change.
(ok, I managed to access the HttpContext......Path, and extract the information from there, but it feels wrong :) )

Also maybe one more question, would it work to create a button somewhere in my Blazor SPA, and in the code for the button, use Navigationmanager to access the download page, like this:
NavigationManager.NavigateTo("/download/Filename.txt");

Thanks for any advice you can give,

Best regards
Mario

Answer 4

Hi @Mahmoud Gomaa , this works in "<a href " but not in NavigationManager.NavigateTo.

I'm trying to download multiple files on a single button click, any ideas?