Published on: 27 October, 2017

How to download a file using .Net Web API MVC?

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In this article, you will learn how to download a file in Web API MVC. We will use HTTP Get API method to perform this download action with one single parameter which will accept the file name. Here is the full code.

//import namespaces
using System.IO;
using System.Net.Http.Headers;

[HttpGet]
public HttpResponseMessage DownloadFile(string fileName)
{
	if (!string.IsNullOrEmpty(fileName))
	{
		string filePath = "/images/";
		string fullPath = AppDomain.CurrentDomain.BaseDirectory + filePath + "/" + fileName;
		if (File.Exists(fullPath))
		{

			HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
			var fileStream = new FileStream(fullPath, FileMode.Open);
			response.Content = new StreamContent(fileStream);
			response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                        response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
			response.Content.Headers.ContentDisposition.FileName = fileName;
			return response;
		}
	}

	return new HttpResponseMessage(HttpStatusCode.NotFound);
}

So how does the code work? Basically, the API will accept a query string which is the file name. We can get the root path of our project by using the following code.

AppDomain.CurrentDomain.BaseDirectory

What we need to do next is to make sure if the user has passed the file name in the query string and if they are, we then check using System.IO.File to see if the file exists on the server. To test it, you can just need to call the API path in your HTML code. See example below and change the API path accordingly as this is just an example only.

<a href='/APIPath/DownloadFile?fileName=ImageName.jpg'>Download file</a>

Comments

Anurag
18 January, 2018
You gotta swap these two lines: response.Content.Headers.ContentDisposition.FileName = fileName; response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment"); Initialize content disposition first and then set file name.
andy
18 January, 2018
Hi Anurag, Thanks for correcting the codes. I have updated as advised.
Stamatis
05 April, 2018
Very good tutorial. It works with very efficiently written code. Thank you very much for this!
Bhavesh Parmar
28 June, 2018
Hey!! I was faced trouble when i publish the web api and i was got error- 500 internal server error please give me suggestion
andy
28 June, 2018
Hi Bhavesh, Would you be able to turn off the customErrors mode to OFF in web.config file? It should tell you more details about what is the error.
mike
09 August, 2018
Worked great out of the box...thanks so much!
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