web api 2 post with parameter - must use json.stringyfi - angularjs

Question

I'm using angularjs and I'm trying to make a HttpPost call to my web api.
My api method:
[HttpPost]
[Route("authentication/getkey")]
public IHttpActionResult GetKey([FromBody]string password) {
//Do stuff
}
my call:
service.getKey = function (password) {
return $http.post('api/authentication/getkey', JSON.stringify(password))
.then(function(result) {
return result.data;
});
}
Now this works fine, but do I really need to use JSON.stringify? I tried sending it like below, but all of them get password = null. Do I have to use JSON.stringify or am I doing it wrong in my other examples?
//Doesnt work
service.getKey = function (password) {
return $http.post('api/authentication/getkey', password)
.then(function(result) {
return result.data;
});
}
//Doesnt work
service.getKey = function (password) {
return $http.post('api/authentication/getkey', {password})
.then(function(result) {
return result.data;
});
}

Answer 1

If you don't want to use JSON.stringify, the other option will be to send the data as application/x-www-form-urlencoded as pointed in other answer as well. This way you are sending the data as form data. I'm not sure about the syntax of the $http.post Shortcut method but the idea is the same.
service.getKey = function (password) {
$http({
method: 'POST',
url: 'api/authentication/getkey',
data: $.param({ '': password }),
headers: {
'Content-Type': 'application/x-www-form-urlencoded'
}
})
.then(function(result) {
return result.data;
});

Answer 2

From Microsoft's Web API official documentation about Parameter Binding in ASP.NET Web API:
When a parameter has [FromBody], Web API uses the Content-Type header to select a formatter. In this example, the content type is "application/json" and the request body is a raw JSON string (not a JSON object).
Angular $http service sends Content-Type: application/json as header by default in POST requests, as you can see from the official docs, so Web API is trying to bind your request body using his JsonFormatter. Because of this you have to provide him a well formatted Json string (not a Json Object with a string inside) to correctly bind his raw string parameter.
As a side note, you could also send a request using application/x-www-form-urlencoded as Content-Type header, but then you will have to format your body as form parameters (using something similar to jQuery $.param( .. ))