curli-bus/src/Handlers/HandlerModel.ts

Simple Command Bus Implementation (CQRS) for NodeJS/Typescript.

import {CommandInstanceType, HandlerType, HandlerFunctionType} from '../Types';

export class HandlerModel {

    public constructor (
        private commandName: string,
        private handler: HandlerType | HandlerFunctionType
    ) {
    }

    public isThisCommandName (commandName: string): boolean {
        return (this.commandName === commandName);
    }

    public callHandler<T> (command: CommandInstanceType, options?: T): any {
        const handler = this.handler;

        if (this.determineHandlerIsFunction(handler)) {
            return (handler as HandlerFunctionType)(command, options);
        } else {
            return (handler as HandlerType).handleCommand(command, options);
        }
    }

    private determineHandlerIsFunction (
        handler: HandlerType | HandlerFunctionType
    ): handler is HandlerFunctionType {

        // if it doesn't have the method handleCommand, it is a function.
        if (!(handler as HandlerType).handleCommand) {
            return true;
        }
        return false;
    }

}