ByteArray to IFormFile

I am developing some REST API with C# and Net Core
I have a function in my repository which accepts a parameter of type IFormFile.

public async Task<bool> UploadFile(IFormFile file)
{
    // do some stuff and save the file to azure storage
}

This function is called by a controller method which pass it the uploaded file

public class FileController : Controller
{
    public async Task<IActionResult> UploadDoc(IFormFile file
    {
        // Call the repository function to save the file on azure
        var res = await documentRepository.UploadFile(file);
    }
}

Now I have another function that calls an external API which returns a file as a byte array. I'd like to save this byte array using the repository.UploadFile method but I can't cast the byte array object to IFormFile.
Is it possible?

Solution

Your repo shouldn't be using IFormFile. That's an abstraction that only applies to one particular method of HTTP file transfer (namely a multipart/form-data encoded request body). Something like your repo should have no knowledge of the source of the file (HTTP), nor how it was transmitted (multipart/form-data vs application/json for example).

Instead, you should use Stream for your param. In your UploadDoc action, then, you can simply do:

using (var stream = file.OpenReadStream())
{
    await documentRepository.UploadFile(stream);
}

And, where you have just a byte array:

using (var stream = new MemoryStream(byteArray))
{
    await documentRepository.UploadFile(stream);
}

You might also consider adding an overload of UploadFile that takes a byte[], as creating a new memory stream from a byte array just to have a stream is a waste of resources. However, a byte[] has to be handled differently than a Stream, so it may require some duplication of logic to go that route. You'll need to evaluate the tradeoffs.