[c#] Optional Parameters in Web Api Attribute Routing

I want to handle POST of the following API-Call:

/v1/location/deviceid/appid

Additional Parameter are coming from the Post-Body.

This all works fine for me. Now I wnat to extend my code by allowing "deviceid" and/or "appid" and/or BodyData to be null:

/v1/location/deviceid
/v1/location/appid
/v1/location/

These 3 URLs should responded by the same route.

My first approach (BodyData required):

[Route("v1/location/{deviceid}/{appid}", Name = "AddNewLocation")]
public location_fromuser Post(string deviceid = null, string appid = null, [FromBody] location_fromuser BodyData)
{
    return repository.AddNewLocation(deviceid, appid, BodyData);
}

This does not work and returns a compile error:

"optional Parameters must be at the end"

Next try:

[Route("v1/location/{deviceid}/{appid}", Name = "AddNewLocation")]
public location_fromuser Post([FromBody] location_fromuser BodyData, string deviceid = null, string appid = null)

Now my function AddNewLocation() get always an BodyData=null - even if the call send the Body.

Finally I set all 3 Parameter optional:

[Route("v1/location/{deviceid}/{appid}", Name = "AddNewLocation")]
public location_fromuser Post(string deviceid = null, string appid = null, [FromBody location_fromuser BodyData = null)

Don´t work:

Optional parameter BodyData is not supported by FormatterParameterBinding.

Why do I want a solution with optional Parameters? My Controller handles just the "adding of a new Location" via a POST.

I want to send on wrong data my own exceptions or error messages. Even if the call has missing values. In this case I want to be able to decide to throw an exception or Setting Defaults by my code.

Converting my comment into an answer to complement @Kiran Chala's answer as it seems helpful for the audiences-

When we mark a parameter as optional in the action uri using ? character then we must provide default values to the parameters in the method signature as shown below:

MyMethod(string name = "someDefaultValue", int? Id = null)

Another info: If you want use a Route Constraint, imagine that you want force that parameter has int datatype, then you need use this syntax:

[Route("v1/location/**{deviceOrAppid:int?}**", Name = "AddNewLocation")]

The ? character is put always before the last } character

For more information see: Optional URI Parameters and Default Values