How to send FormData to WCF REST containing file and text?

Question

JavaScript

Hello, actually the question is in the topic, how to send a file with some related data via HTTP to a WCF service? An example of incoming data might look like:

[DataContract]
public class D
{
    [DataMember]
    public Stream File { get; set; }
    [DataMember]
    public string Text { get; set; }
}

And the JS code I send is this:

let formData = new FormData();
formData.append("File", params.circuitFile);
formData.append("Text", fileName);
return this.http.post('http://localhost/CircuitOptimizer.Service/start', formData)

Interested in how to correctly implement the method in WCF itself, because no matter how I tried, the file can be sent only if it is not part of formData, but the only parameter. And sending of difficult object interests.