ASP.NET Web API | File Upload and Download

R M Shahidul Islam Shahed
3 min readApr 26, 2023

ASP.NET Web API is a framework for building HTTP services that can be accessed by various clients, including web browsers, mobile devices, and desktop applications. It is built on top of the ASP.NET framework and uses the HTTP protocol to transmit data in a lightweight and efficient manner.

Web APIs are typically used to expose data and functionality from a web application to other systems or clients. For example, an e-commerce website may use a Web API to expose product information and inventory levels to mobile apps and other third-party systems.

Uploading and downloading files is a common requirement for web applications. In an ASP.NET Web API, file upload and download can be implemented using the HttpClient class to send and receive files.

To upload a file in an ASP.NET Web API, we have created a service that handles upload and download files.

Here are the full project steps,

Project structure

Service for Manage Files

public interface IManageImage
{
Task<string> UploadFile(IFormFile _IFormFile);
Task<(byte[], string, string)> DownloadFile(string FileName);
}

Service Implementation

public class ManageImage : IManageImage
{
public async Task<string> UploadFile(IFormFile _IFormFile)
{
string FileName = "";
try
{
FileInfo _FileInfo = new FileInfo(_IFormFile.FileName);
FileName = _IFormFile.FileName + "_" + DateTime.Now.Ticks.ToString() + _FileInfo.Extension;
var _GetFilePath = Common.GetFilePath(FileName);
using (var _FileStream = new FileStream(_GetFilePath, FileMode.Create))
{
await _IFormFile.CopyToAsync(_FileStream);
}
return FileName;
}
catch (Exception ex)
{
throw ex;
}
}
public async Task<(byte[], string…

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