$singleton
You can directly call exposed functions of your shared singletons through REST.
Singleton functions are called in POST requests with the $singleton
command and without ()
. For example, if you have defined a buildVehicle()
function in the VehicleFactory
shared singleton class, you could call it using the following request:
/rest/$singleton/VehicleFactory/buildVehicle
with data in the body of the POST request: ["truck"]
En el lenguaje 4D, esta llamada equivale a:
$singleton:=cs.VehicleFactory.me.buildVehicle("truck")
Keep in mind that only functions with the exposed
keyword can be directly called from REST requests.
Llamadas de las funciones
Singleton functions must always be called using REST POST requests (a GET request will receive an error). La sintaxis formal es:
/rest/$singleton/SingletonClass/SingletonClassFunction
All 4D code called from REST requests must be thread-safe if the project runs in compiled mode, because the REST Server always uses preemptive processes in this case (the Use preemptive process setting value is ignored by the REST Server).
You can restrict calls to specific singleton functions by configuring appropriate privileges in the roles.json file.
Parámetros
You can send parameters to singleton functions. On the server side, they will be received in the declared parameters of the singleton class functions.
Sending parameters to singleton functions is exactly the same as sending parameter to ORDA class functions. Please refer to the Parameters paragraph of the "Calling class functions" page for a detailed description.
Ejemplo
You have created a simple shared singleton with an exposed function:
//class mySingleton
shared singleton Class constructor()
exposed Function sayHello ($value : Text)
return "Hello "+$value
The mySingleton
class and sayHello
function are listed when you call the $catalog
command.
A continuación, puede ejecutar esta petición:
POST /rest/$singleton/mySingleton/sayHello
Cuerpo de la petición: ["John"]
Respuesta
{
"result": "Hello John"
}