How to specify an input file to DOM of using AngleSharp?

Question

Using AngleSharp, how do I specify file to fill in <input type="file" name="myInputFile">? I've read this StackOverflow question, but it seems like different than my intended case. I'm trying to fill a form programmatically while uploading a file of my choice.

Answer 1

Every IHtmlInputElement has a Files property that can be used to add files.

var input = document.QuerySelector<IHtmlInputElement>("input[type=file][name=myInputFile]");
input?.Files.Add(file);

In the previously used example the file variable refers to any IFile instance. AngleSharp is a PCL does not come with a proper implementation out of the box, however, a simple one may look like:

class FileEntry : IFile
{
    private readonly String _fileName;
    private readonly Stream _content;
    private readonly String _type;
    private readonly DateTime _modified;

    public FileEntry(String fileName, String type, Stream content)
    {
        _fileName = fileName;
        _type = type;
        _content = content;
        _modified = DateTime.Now;
    }

    public Stream Body
    {
        get { return _content; }
    }

    public Boolean IsClosed
    {
        get { return _content.CanRead == false; }
    }

    public DateTime LastModified
    {
        get { return _modified; }
    }

    public Int32 Length
    {
        get
        {
            return (Int32)_content.Length;
        }
    }

    public String Name
    {
        get { return _fileName; }
    }

    public String Type
    {
        get { return _type; }
    }

    public void Close()
    {
        _content.Close();
    }

    public void Dispose()
    {
        _content.Dispose();
    }

    public IBlob Slice(Int32 start = 0, Int32 end = Int32.MaxValue, String contentType = null)
    {
        var ms = new MemoryStream();
        _content.Position = start;
        var buffer = new Byte[Math.Max(0, Math.Min(end, _content.Length) - start)];
        _content.Read(buffer, 0, buffer.Length);
        ms.Write(buffer, 0, buffer.Length);
        _content.Position = 0;
        return new FileEntry(_fileName, _type, ms);
    }
}

A more sophisticated one would auto-determine the MIME type and have constructor overloads to allow passing in (local) file paths etc.

Hope this helps!