Controller Scope

In Moost, a controller's scope refers to the lifecycle of its instance. There are two primary scopes:

• SINGLETON: By default, each Moost controller is a singleton. It means a single controller instance is created and reused for different events. You don't need to do anything for this; it's the default behavior.
• FOR_EVENT: A new controller instance is created for each event when its scope is defined as 'FOR_EVENT'. This is useful if you need to maintain a state or use event-based resolvers at the class level during an event's lifecycle.

Defining 'FOR_EVENT' Scope

To specify a controller's scope as 'FOR_EVENT', apply the @Injectable('FOR_EVENT') decorator before the @Controller() decorator.

Here's an example:

event.controller.ts

import { Get } from '@moostjs/event-http'
import { Controller, Injectable, Param } from 'moost'

@Injectable('FOR_EVENT')    
@Controller('api')
export class EventController {
    @Param('name') name: string;  

    @Get('hello/:name')
    hello() {
        return `Hello, ${this.name}!`
    }
}

In this case, the EventController is defined with 'FOR_EVENT' scope using @Injectable('FOR_EVENT') decorator. Because of the 'FOR_EVENT' scope, the @Param('name') resolver is usable at the class level. In the hello method, this.name will contain the 'name' parameter value from the event.

WARNING

Avoid dependencies between controllers with differing scopes. If a controller is in SINGLETON scope, it shouldn't depend on a class in FOR_EVENT scope. Since singleton dependencies are instantiated only once, creating a new instance for each event isn't possible. However, a controller in FOR_EVENT scope can depend on a class in SINGLETON scope.