Service Context

Service Context

A Context object is created to group informations about the current request being handled. This Context can be accessed by service methods.

The Context is represented by the ServiceContext class and has the following properties:

Property	Type	Description
request	express.Request	The request object
response	express.Response	The response object
next	express.NextFunction	The next function. It can be used to delegate to the next middleware registered for the processing of the current request.
language	string	The resolved language to be used to handle the current request.
accept	string	The preferred media type to be used to respond the current request.

See Types and languages to know how the language and accept fields are calculated.

The @Context decorator can be used on service method's arguments or on service class properties to bind the argument or the property to the current context object.

A Context usage example:

 @Path("context")
 class TestService {
   @Context
   context: ServiceContext;

   @GET
   sayHello() {
      switch (this.context.language) {
         case "en":
            return "Hello";
         case "pt":
            return "Olá";
      }
      return "Hello";
   }
 }

We can use the decorator on method arguments too:

 @Path("context")
 class TestService {

   @GET
   sayHello(@Context context: ServiceContext) {
      switch (context.language) {
         case "en":
            return "Hello";
         case "pt":
            return "Olá";
      }
      return "Hello";
   }
 }

You can use, also, one of the other decorators to access directly one of the Context property. It is a kind of sugar syntax.

• @ContextRequest: To access ServiceContext.request
• @ContextResponse: To access ServiceContext.response
• @ContextNext: To access ServiceContext.next
• @ContextLanguage: To access ServiceContext.language
• @ContextAccept: To access ServiceContext.accept

 @Path("context")
 class TestService {

   @GET
   sayHello(@ContextLanguage language: string) {
      switch (language) {
         case "en":
            return "Hello";
         case "pt":
            return "Olá";
      }
      return "Hello";
   }
 }