Return Excel File from WebAPI ASPNetCore

Question

I am trying to create the WebAPI which will return an Excel file by using ClosedXML Library.

It's all working fine, if I return the FileStreamResult. But if I changed it to HttpResponseMessage as discussed here Web API Return A File, I couldn't download a file or see the content anymore and getting JSON string.

I would like to know how I could extract the File Content from this HttpResponseMessage.

I tested in browser or PostMan tool and all I got back is JSON String:

{
      "version": {
        "major": 1,
        "minor": 1,
        "build": -1,
        "revision": -1,
        "majorRevision": -1,
        "minorRevision": -1
      },
      "content": {
        "headers": [
          {
            "key": "Content-Disposition",
            "value": [
              "attachment; filename=ERSheet.xlsx"
            ]
          },
          {
            "key": "Content-Type",
            "value": [
              "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
            ]
          }
        ]
      },
      "statusCode": 200,
      "reasonPhrase": "OK",
      "headers": [],
      "requestMessage": null,
      "isSuccessStatusCode": true
    }

My Code is as follow:

[HttpGet("ERSheet2")]
        public HttpResponseMessage ER_GenerateWBLWorksheet2()
        {
            MemoryStream stream = new MemoryStream();
            var workbook = new XLWorkbook();

            var SheetNames = new List<string>() { "15-16", "16-17", "17-18", "18-19", "19-20" };

            foreach (var sheetname in SheetNames)
            {
                var worksheet = workbook.Worksheets.Add(sheetname);

                worksheet.Cell("A1").Value = sheetname;
            }

            workbook.SaveAs(stream);
            stream.Seek(0, SeekOrigin.Begin);

            HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
            result.Content = new ByteArrayContent(stream.ToArray());
            result.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
            result.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
            result.Content.Headers.ContentDisposition.FileName = "ERSheet.xlsx";
            return result;
        }

Updated

This one is different from this question Download file with ClosedXML because I mentioned that I already made it work by using 'FileStreamResult'. I am asking this because of this comment "Better to return HttpResponseMessage with StreamContent inside of it." made in this thread Web API Return A File. So, trying to use HttpResponseMessage in .Net Core and didn't know that it doesn't support anymore as Darin's answer.

This ResponseMessage doesn't have any content. I mean content of Excel file. Or am I not right? — Roman Marusyk
– Roman Marusyk, Commented Jan 19, 2017 at 16:06
Sorry, I am confused. My ResponseMessage does not contain any content or HttpResponseMessage cannot be used to hold any content? — TTCG
– TTCG, Commented Jan 19, 2017 at 16:10
First, your JSON String doesn't have any content of Excel file — Roman Marusyk
– Roman Marusyk, Commented Jan 19, 2017 at 16:14

Darin Dimitrov · Accepted Answer · 2017-01-19 16:30:48Z

15

ASP.NET Web API running on .NET Core doesn't support HttpResponseMessage anymore. So basically it tries to serialize the instance of this object that you are returning to JSON (as if it was a simple view model of yours). There are some compatibility shim hacks which you could use but in general I would recommend you using the more idiomatic approach - return an IActionResult instance from your action:

[HttpGet("ERSheet2")]
public IActionResult ER_GenerateWBLWorksheet2()
{
    using (MemoryStream stream = new MemoryStream())
    {
        var workbook = new XLWorkbook();

        var SheetNames = new List<string>() { "15-16", "16-17", "17-18", "18-19", "19-20" };

        foreach (var sheetname in SheetNames)
        {
            var worksheet = workbook.Worksheets.Add(sheetname);

            worksheet.Cell("A1").Value = sheetname;
        }

        workbook.SaveAs(stream);
        stream.Seek(0, SeekOrigin.Begin);

        return this.File(
            fileContents: stream.ToArray(), 
            contentType: "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", 

            // By setting a file download name the framework will
            // automatically add the attachment Content-Disposition header
            fileDownloadName: "ERSheet.xlsx"
        );
    }
}

edited Jan 19, 2017 at 16:30

answered Jan 19, 2017 at 16:16

Darin Dimitrov

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3 Comments

TTCG Over a year ago

Yeah, it must be the main reason. I am trying to return it in HttpResponse coz of this line in another answer. "Better to return HttpResponseMessage with StreamContent inside of it." Thanks.

Darin Dimitrov Over a year ago

Yes, but this answer is about ASP.NET Web API running on the full .NET framework, not for .NET Core.

TTCG Over a year ago

How do you see whether the question is related to .Net core or Standard .Net? I couldn't find those hashtags anywhere on the page.

Karen Healey · Accepted Answer · 2017-01-20 18:52:32Z

0

I believe you should be using:

response.Content = new ByteArrayContent(stream.GetBuffer());

However, I'm having a problem getting this to work for Angular2. It DOES work with Angular1.

answered Jan 20, 2017 at 18:52

Karen Healey

591 gold badge1 silver badge6 bronze badges

1 Comment

matt2000 Over a year ago

Its not clear how this answer is relevant. The question doesn't mention using Angular. But maybe you see something I don't and can help the Asker clarify the question?

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