How to download memory stream object via angularJS and webaAPI2

Question

I have a project where I am using NPOI to generate Excel document from my Angular application. I have the calls being made from my angular service to my webapi controller as follows:

function exportReportToExcel(report) {
            return $http.post('reportlibrary/exportReport/', report, {
            }).then(function (response) {
                return response.data;
            });
        };

Within the controller I make the following call

[HttpPost]
public HttpResponseMessage ExportReport([FromBody]DTOs.Report report)
{
  try
     {
      IReportPersistenceManager manager = ContainerConfigurator.Instance.Resolve<IReportPersistenceManager>();

      MemoryStream ms = new MemoryStream();
      //we have to pass to the NOPI assemble file type as well as file name 
     //since we only deal with excel for now we will set it but this could be configured later.
      long id = report.ReportId;
      string mimeType = "application/vnd.ms-excel";
      string filename = "unknown";
      manager.ExportDataToExcel(id, (name, mime) =>
      {
       mimeType = mime;
       filename = name;
       return ms;
      });
     ms.Position = 0;

    var response = new HttpResponseMessage();
    response.Content = new ByteArrayContent(ms.ToArray());
    response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.ms-excel");       
   return (response);
   }
   catch (Exception)
   {
   //error
   return new HttpResponseMessage(System.Net.HttpStatusCode.BadRequest);
   }
}

This is a migration from an MVC app and previously I was able to return the object using System.IO.File to return the object as well as close the stream.

I've never done this with Angular but from what I have read it appears I can drop the memorystream object into a byteArray and pass that back to the client.

If this is the correct approach how to I unravel this object once it comes back to the angular service and controller.

The goal here is to allow the user to download a previously saved report as an Excel file.

Am I on the right track? Is there a more efficient way to download a memory stream object? How can I pass this context to the browser?

thanks in advance

Answer 1

I had a similar problem. I solved that changing the endpoint to support GET and calling this method from a new tab.

So from your angular app you have to create a new tab pointing to the path that calls the method that generate your document. You can open a tab with the next code:

$window.open(path)

I think that in the next link you can have all the information that you need:

Download file from an ASP.NET Web API method using AngularJS

I hope that it helps.