Download single Asset from private repository in c#

[IT-Emilio]

Hi everyone,

I am building a C# application that should be able to download an asset from a specific release of my private repository. I have created a personal token to access the files and have given it the necessary permissions. According to the Git documentation, I should use a URL like: “https://github.com/{user}/{repo}/releases/download/{tag}/{asset-name}”

However, no matter what I try, I keep receiving a “404” response from the server. This is strange because when I paste the same URL into the browser, the resource downloads correctly.

Here is a code example of what I did on my application, but I have tried several options and none of these seems to work:

public static async Task DownloadSingleAssetFile(string Token, string DesideredVersion, string ASSETNAME, string DestinationPath)
{
    var url = $"https://github.com/MYNAME/REPONAME/releases/download/{DesideredVersion}/{ASSETNAME}";
    using (var client = new System.Net.Http.HttpClient())
    {
        var credentials = string.Format(System.Globalization.CultureInfo.InvariantCulture, "{0}:", Token);
        credentials = Convert.ToBase64String(System.Text.Encoding.ASCII.GetBytes(credentials));
        client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Basic", credentials);
        var contents = client.GetByteArrayAsync(url).Result;
        System.IO.File.WriteAllBytes(DestinationPath, contents);
    }
}

So, I’m wondering if it’s even possible to do what I’m trying to achieve. It seems odd that it’s impossible to download a single asset from a repository. I’ve found other people online who seem to be having the same problem, but I haven’t found any solutions.

Interestingly, when I try to use a URL like: “https://github.com/{user}/{repo}/archive/refs/tags/{release-tag}.zip” with the same code, it works correctly.

I hope someone can help me with this. Thanks for your time!

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[asiryan]

Hello! You need to use your file's URL like this: https://raw.githubusercontent.com/[proj]/[repo]/main/[file]

[IT-Emilio]

The support team from Git got back to me. They suggested using a URL like: https://api.github.com/repos/{user}/{repo}/releases/assets/{asset-name}

[jdevfullstack]

I asked Copilot to check and correct it, again, this may not be correct but it points out valid points that you can use or may realize

answer from Copilot :

This C# method is designed to download a specific asset file from a GitHub repository's release. Here's a breakdown of what it does:

1. It constructs a URL to the desired asset file in a specific release of a GitHub repository.
2. It creates a new HttpClient instance to make HTTP requests.
3. It prepares the authorization header by encoding the provided GitHub token in Base64 and setting it as the Authorization header in the HttpClient.
4. It sends a GET request to the constructed URL to download the asset file.
5. It writes the downloaded file to the specified destination path.

The method is marked as async but it's not correctly using async/await pattern. The line var contents = client.GetByteArrayAsync(url).Result; is synchronously blocking on the result of an asynchronous operation, which can lead to deadlocks in certain contexts (like in UI applications).

A better approach would be to await the GetByteArrayAsync method:

public static async Task DownloadSingleAssetFile(string Token, string DesideredVersion, string ASSETNAME, string DestinationPath)
{
    var url = $"https://github.com/MYNAME/REPONAME/releases/download/{DesideredVersion}/{ASSETNAME}";
    using (var client = new System.Net.Http.HttpClient())
    {
        var credentials = string.Format(System.Globalization.CultureInfo.InvariantCulture, "{0}:", Token);
        credentials = Convert.ToBase64String(System.Text.Encoding.ASCII.GetBytes(credentials));
        client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Basic", credentials);
        var contents = await client.GetByteArrayAsync(url);
        System.IO.File.WriteAllBytes(DestinationPath, contents);
    }
}

Please replace MYNAME and REPONAME with your actual GitHub username and repository name. Also, ensure that the GitHub token has the appropriate permissions to access the repository and its releases.

[asiryan]

@IT-Emilio , @jdevstatic

I download GitHub files using Octokit.NET and HttpClient:

var gitHubClient = new GitHubClient(new ProductHeaderValue(_settings.AppName));
var gitHubCredentials = new Credentials(token: _settings.GitHubToken);
gitHubClient.Credentials = gitHubCredentials;

// get raw file url
var repositoryContents =
    await gitHubClient.Repository.Content.GetAllContentsByRef(
    environmentSettings.Owner,
    environmentSettings.Repository,
    environmentSettings.Branch);

var firstOrDefault = repositoryContents.FirstOrDefault(c => c.Path == path);
var downloadUrl = firstOrDefault?.DownloadUrl;

// download raw file content
using var httpClient = new HttpClient();
var credentials = string.Format(System.Globalization.CultureInfo.InvariantCulture, "{0}:", _settings.GitHubToken);
credentials = Convert.ToBase64String(System.Text.Encoding.ASCII.GetBytes(credentials));
httpClient.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Basic", credentials);

return await httpClient.GetAsync(downloadUrl, cancellationToken)
    .ConfigureAwait(false);

[jdevfullstack]

is that your latest code ? yes consuming GitHub API is usually done using Octokit, what's the next problem now ?

[IT-Emilio]

I discovered that the issue was with the URL. By using CURL from the command line, I was finally able to download the individual asset. So in c#, I decided to download the asset using an HTTP request, without employing the Octokit package. Here’s how I did it

url = $"https://api.github.com/repos/{user}/{repository}/releases/assets/{asset_id}";
using HttpClient dwnclient = new HttpClient();
dwnclient.DefaultRequestHeaders.Add("Authorization", $"Bearer {Token}");
dwnclient.DefaultRequestHeaders.Add("User-Agent", "request");
dwnclient.DefaultRequestHeaders.Add("Accept", "application/octet-stream");

if (!string.IsNullOrEmpty(url))
{
    var fileResponse = await dwnclient.GetAsync(url);
    if (fileResponse.IsSuccessStatusCode)
    {
        DestinationPath = Path.Combine(DestinationPath, AssetName);
        using FileStream fs = new FileStream(DestinationPath, System.IO.FileMode.Create);
        await fileResponse.Content.CopyToAsync(fs);
        return new Result(true, $"The asset '{AssetName}' from version '{desideredVersionTag}' has been successfully downloaded.");
    }
    else
    {
        return new Result(false, $"An error occurred while downloading the asset '{AssetName}': {fileResponse.StatusCode}");
    }
}
else
{
    return new Result(false, $"The asset '{AssetName}' is not present in version '{desideredVersionTag}'.");
}

Thanks a lot for your time anyway. 😊

[asiryan]

@jdevstatic yes, it works!
@IT-Emilio thanks for your code too

[leedavi]

Yes, Thankyou, it's been driving me mad all day.