Model binding in ASP.NET Core to map underscores to title case property names

You can use the FromQuery attribute's Name property here.

Example:

public class OauthParameters
{
    [FromQuery(Name = "client_id")]
    public string ClientId { get; set; }

    [FromQuery(Name = "response_type")]
    public string ResponseType { get; set; }

    [FromQuery(Name = "redirect_uri")]
    public string RedirectUri { get; set; }
}