Bind ASP.NET Core action parameter to JWT claim

Question

It is possible to bind actions' parameters via:

• [FromBody] Request body
• [FromForm] Form data in the request body
• [FromHeader] Request header
• [FromQuery] Request query string parameter
• [FromRoute] Route data from the current request
• [FromServices]

I often need to extract something from a JWT, almost always the id (primary key). So I do this (ignore error checking for now):

var id = int.Parse(base.User.FindFirst(ClaimTypes.NameIdentifier)?.Value);

It would be great if I could put that into an attribute binder that would work like this:

public IActionResult doStuff([FromBody] MyModel model, [FromJwt] int id) {
  // id works automatically
}

Or maybe [FromJwtId] instead to make it simpler.

Is such a thing possible?

Answer 1

I think it is possible to create such attributes using HttpParameterBinding.

Microsoft has a tutorial on that.