Upload very large files in Web API with very simple method

We will see a very simple method to upload large files in Web API project using MultipartFormDataStreamProvider.

In this article, we will see a very simple method to upload large files in the Web API project using MultipartFormDataStreamProvider.

We can create a Web API project in Visual Studio 2019/2017/2015. I am using Visual Studio 2017 community edition.
After some time, our project will be created with default templates.

We must change the value of “maxAllowedContentLength” in requestLimits” in webconfiguration file to 1GB. If your upload file size is more than 1GB, please change the settings accordingly.
We gave the value in Bytes.
We must change the settings under system.webServer node in the web.config file.
We can add more settings in the web.config file for the location of our files to be stored.
Our configuration part is over. Now, let’s create a new API controller.
We can add below code to this controller.
public class FileuploadController : ApiController  
        public async Task<bool> Upload()  
                var fileuploadPath = ConfigurationManager.AppSettings["FileUploadLocation"];  
                var provider = new MultipartFormDataStreamProvider(fileuploadPath);  
                var content = new StreamContent(HttpContext.Current.Request.GetBufferlessInputStream(true));  
                foreach (var header in Request.Content.Headers)  
                    content.Headers.TryAddWithoutValidation(header.Key, header.Value);  
                await content.ReadAsMultipartAsync(provider);  
                return true;  
            catch (Exception)  
                return false;  

We created a provider variable with “MultipartFormDataStreamProvider” and content variable with “StreamContent”. Then we added the Request headers to a content variable using a FOR Loop.

Finally, we read the multi-part data from the content variable asynchronously. It will automatically create a file in the given folder. (We gave the output path as a web configuration parameter)

We can use the postman tool to test our Web 
API. Please run our Web API now. After our Web API loaded, we can come to postman tool and using POST method we can send a request to Web API. We must choose “form-data” in the body part and choose “File” as type.
We can click the “Send” button now. After some time, we will get a result.
We got a “true” result. That means, our file upload successfully completed. Now we can check the file location (which we mentioned in the the web.config file).
Please note though our file uploaded successfully, we got a different random file name in the uupload location without any extension.

We can add one 
simple step to rename the file name with the original file name.
//Code for renaming the random file to Original file name  
               string uploadingFileName = provider.FileData.Select(x => x.LocalFileName).FirstOrDefault();  
               string originalFileName = String.Concat(fileuploadPath, "\\" + (provider.Contents[0].Headers.ContentDisposition.FileName).Trim(new Char[] { '"' }));  
               if (File.Exists(originalFileName))  
               File.Move(uploadingFileName, originalFileName);  
               //Code renaming ends...

Please execute the postman with the same file again and see the difference.

Please note, our file successfully uploaded with the original file name. We tested the application with a very small file (less than 2MB).

Now we can test with a large-sized 
file (File size is 708 MB).

After some time, our large file will be uploaded successfully. You can now check the file upload folder and see the new file there.

In this article, we saw very simple steps to upload large files in Web APIs. You can use the same code for any large file. As this is a Web API, we can use this with any client-side application (Windows or Web).

You can get the source code from GitHub

If you like the code, please give me your valuable feedback and if you think, it is a worthy code please give a star on GitHub

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1 thought on “Upload very large files in Web API with very simple method

  1. Arvind Reply

    Instead of using Postman as file upload, if This demo contains page or inside solution for Testing and making real-world use case it makes more sense.

    So, Both File upload from HTML or aspx or cshtml at one place as your service didn’t require any change.

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