C#•7mo ago

Serving static files via a Web API (REST)

Hello, I'd like to set up an image upload system via a REST API in ASP.NET Core 6. I tried to configure my Program.cs, but when I try to get the path via the environment in my service, it's set to Microsoft.Extensions.FileProviders.NullFileProvider and I get a null path. Here's my Program.cs: https://pastebin.com/9hJmEKJn Here is the code where I encounter the problem:

public class LocalFileUploadService : IFileUploadService
{
    private readonly IWebHostEnvironment _environment;

    public LocalFileUploadService(IWebHostEnvironment environment)
    {
        _environment = environment;
    }

    public async Task<string> UploadFileAsync(IFormFile file, string fileName)
    {
        var fileExtension = Path.GetExtension(file.FileName);
        var filePath = Path.Combine(_environment.WebRootPath, "uploads", fileName + fileExtension);

        using (var fileStream = new FileStream(filePath, FileMode.Create))
        {
            await file.CopyToAsync(fileStream);
        }

        return fileName;
    }

    // ...
}

public class LocalFileUploadService : IFileUploadService
{
    private readonly IWebHostEnvironment _environment;

    public LocalFileUploadService(IWebHostEnvironment environment)
    {
        _environment = environment;
    }

    public async Task<string> UploadFileAsync(IFormFile file, string fileName)
    {
        var fileExtension = Path.GetExtension(file.FileName);
        var filePath = Path.Combine(_environment.WebRootPath, "uploads", fileName + fileExtension);

        using (var fileStream = new FileStream(filePath, FileMode.Create))
        {
            await file.CopyToAsync(fileStream);
        }

        return fileName;
    }

    // ...
}

Pastebin

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2 Replies

Kiel•7mo ago

https://stackoverflow.com/questions/59304961/how-can-i-get-access-to-the-iwebhostenvironment-from-within-an-asp-net-core-3-co#comment104851604_59305508

OK I finally reproduced the issue. The API template you use doesn't create a wwwroot folder, which is why you get a NullFileProvider. If you add a wwwroot folder (it can be empty), you'll have a PhysicalFileProvider.

I'm unsure why asp.net works in this way...maybe there's a more robust solution for what you're trying to do - what's your end goal - determining the physical file location to save files in? Is Directory.GetCurrentDirectory() sufficient for your needs?

Lionel Bovy•7mo ago

Thank you very much for the message, I was not aware of this behavior. I also tried it and it works as expected. To answer the second part, I just wanted to make a folder where we could put user avatars and access them directly without having to create an additional endpoint.

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Serving static files via a Web API (REST)