Initial Code Commit
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Alan Bridgeman
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24 changed files with 2691 additions and 2 deletions
244
src/Router.ts
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244
src/Router.ts
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import path from 'path';
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import { Application } from 'express';
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import fse from 'fs-extra';
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import { BaseController } from './controllers/BaseController';
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/**
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* The Router sets up the routes/endpoints for the App.
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*
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* More specifically, it does automatic detection of controllers (and their routes) within the specified folder.
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*
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* A controller is a class that extends the `BaseController` class and uses the `@Controller` decorator.
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* Routes within a controller are defined by methods that use the `@GET` or `@POST` decorators.
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*/
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export class Router {
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/** The default folder name for controllers */
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private readonly DEFAULT_CONTROLLERS_FOLDER = 'routes';
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/** The path to the controllers folder */
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private controllersPath: string;
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/**
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* Create a new Router
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*
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* @param controllersPath The path to the controllers folder (default is 'routes' in the current working directory)
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* @throws Error if the controllers path is not a valid directory
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*/
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constructor(controllersPath: string = path.join(process.cwd(), this.DEFAULT_CONTROLLERS_FOLDER)) {
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if(!fse.existsSync(controllersPath) || !fse.statSync(controllersPath).isDirectory()) {
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throw new Error('The controllers path must be a valid directory');
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}
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this.controllersPath = path.resolve(controllersPath);
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}
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/**
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* Check if a file is a controller
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*
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* Note, if the specified "file" is a directory, this method will recurse into the directory and return all controllers found in the directory.
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*
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* @param file The file to check if it is a controller
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* @param folder The folder that the file is in
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* @returns The controller class (or list of controller classes) in the "file" or null if the file is not a controller
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*/
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private async checkIfControllerFile(file: string, folder: string): Promise<any /*BaseController*/ | any[]/*BaseController[]*/ | null> {
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// Get the path to the specific file
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const controllerPath = path.join(folder, file);
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// Check if the path is a directory/folder
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const stats = await fse.stat(controllerPath);
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if(stats.isDirectory()) {
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// Recurse into the directory
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const controllersFoundInDir = await Promise.all((await fse.readdir(controllerPath)).map(file => this.checkIfControllerFile(file, controllerPath)));
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const controllersInDir = controllersFoundInDir.filter(controller => controller !== null);
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return controllersInDir.length === 0 ? null : controllersInDir.flat();
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}
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// We only want to load JavaScript files (Note, Typescript files get compiled to JavaScript files)
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if(!controllerPath.endsWith('.js')) {
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return null;
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}
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// Load the file as a module
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const controllerModule = require(controllerPath);
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console.log(`${controllerPath} loaded successfully: ${JSON.stringify(Object.keys(controllerModule))} exports found.`)
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// Get all the classes in the module that are controllers
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//
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// Note: We filter by if the class extends the `BaseController` class.
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// This is because native JavaScript doesn't have decorators (which are used to mark a class as a controller).
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// Consequently, we enforce that all controllers in addition to using the decorator must extend the `BaseController` class so that we can identify them.
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// Further, note we can't do this as part of the decorator because of the way decorators get transpiled to JavaScript.
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const controllers = Object.keys(controllerModule)
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.filter(key => typeof controllerModule[key] === 'function' && /^\s*class\s+/.test(controllerModule[key].toString()))
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.filter(exportedClassName => controllerModule[exportedClassName].prototype instanceof BaseController)
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.map(controllerClassName => {
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return controllerModule[controllerClassName];
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});
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switch(controllers.length) {
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case 0:
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return null;
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case 1:
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return controllers[0];
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default:
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return controllers.flat();
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}
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}
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/**
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* Get the routes in a controller
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*
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* A route is defined by a method in the controller that has the `@GET` or `@POST` decorator.
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*
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* @param controller The controller to get the routes from
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* @returns The routes in the controller
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*/
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private getRoutesInController(controller: any) {
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// Loop over all the methods in the provided class looking for methods that use the GET decorator
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const pathsGET = Object.getOwnPropertyNames(controller.prototype)
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// Find all methods that have a Get metadata key (GET decorator)
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.filter((method) => Reflect.getMetadata('Get', controller.prototype, method))
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.map((method) => {
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// Get the method
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const fn = controller.prototype[method];
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// Get the path
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const path = Reflect.getMetadata('Get', controller.prototype, method) as string;
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return path;
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});
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// Loop over all the methods in the provided class looking for methods that use the POST decorator
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const pathsPOST = Object.getOwnPropertyNames(controller.prototype)
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// Find all methods that have a Post metadata key (POST decorator)
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.filter((method) => Reflect.getMetadata('Post', controller.prototype, method))
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.map((method) => {
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// Get the method
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const fn = controller.prototype[method];
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// Get the metadata object (which contains a path and middleware)
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const postRoute = Reflect.getMetadata('Post', controller.prototype, method);
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const path = postRoute.path;
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return path;
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});
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return {
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GET: pathsGET,
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POST: pathsPOST
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}
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}
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/**
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* Setup the controllers for the application
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*
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* This loops over all the "files" in the directory (this includes subdirectories) and finds any controllers.
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* A controller being a class that extends the BaseController class and uses the `@Controller` decorator.
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* Once it knows the controllers it adds the routes they contain to the Express app.
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* Routes are defined by methods in the controller that have the `@GET` or `@POST` decorators.
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*
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* @param app The Express app to add the routes to
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*/
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private async setupControllers(app: Application) {
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// Get the list of files in the controllers folder
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const files = await fse.readdir(this.controllersPath);
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// Get the controller classes from the files
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const loadedControllers = (await Promise.all(
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files.map(file => this.checkIfControllerFile(file, this.controllersPath/*, app*/))
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)).filter(controller => controller !== null);
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const addedRoutes: string[] = [];
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// Get all controllers that have the child controller decorator
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const controllersWithChildControllers = loadedControllers.filter(controller => Reflect.getMetadata('ChildController', controller) !== undefined);
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// Get all those controllers that are designated as children controllers by parent controllers
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const childrenControllers = controllersWithChildControllers.map(controller => Reflect.getMetadata('ChildController', controller));
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// Get the exclusive set of controllers that don't fit in the group of controllers with child controllers OR a child controller themselves
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const controllersWithoutChildren = loadedControllers.filter(controller => !controllersWithChildControllers.includes(controller) && !childrenControllers.includes(controller));
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// Take the list of controllers with child controllers and the list without children (that excludes children themselves)
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// And forma a list that has all child controllers remove
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const topLevelControllers = [...controllersWithChildControllers, ...controllersWithoutChildren];
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// Add the routes for the child controllers to the list of added routes WITHOUT calling the setup method (as this is called in the parent controller's setup method)
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childrenControllers
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.forEach(decoratedController => {
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if(Array.isArray(decoratedController)) {
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decoratedController.forEach(decoratedControllerCls => {
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const controller = Reflect.getMetadata('originalClass', decoratedControllerCls);
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const routes = this.getRoutesInController(controller);
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routes.GET.forEach((path: string) => {
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addedRoutes.push(`GET ${path} from ${(new controller()).constructor.name}`);
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});
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routes.POST.forEach((path: string) => {
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addedRoutes.push(`POST ${path} from ${(new controller()).constructor.name}`);
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});
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});
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}
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else {
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const controller = Reflect.getMetadata('originalClass', decoratedController);
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const routes = this.getRoutesInController(controller);
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routes.GET.forEach((path: string) => {
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addedRoutes.push(`GET ${path} from ${(new controller()).constructor.name}`);
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});
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routes.POST.forEach((path: string) => {
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addedRoutes.push(`POST ${path} from ${(new controller()).constructor.name}`);
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});
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}
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});
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// Add the routes for the top level controllers to the list of added routes and call the setup method
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topLevelControllers
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.forEach(decoratedController => {
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if(Array.isArray(decoratedController)) {
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decoratedController.forEach(decoratedControllerCls => {
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const controller = Reflect.getMetadata('originalClass', decoratedControllerCls);
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const routes = this.getRoutesInController(controller);
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routes.GET.forEach((path: string) => {
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addedRoutes.push(`GET ${path} from ${(new controller()).constructor.name}`);
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});
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routes.POST.forEach((path: string) => {
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addedRoutes.push(`POST ${path} from ${(new controller()).constructor.name}`);
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});
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decoratedControllerCls.setup(app);
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});
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}
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else {
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const controller = Reflect.getMetadata('originalClass', decoratedController);
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const routes = this.getRoutesInController(controller);
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routes.GET.forEach((path: string) => {
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addedRoutes.push(`GET ${path} from ${(new controller()).constructor.name}`);
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});
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routes.POST.forEach((path: string) => {
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addedRoutes.push(`POST ${path} from ${(new controller()).constructor.name}`);
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});
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(decoratedController as any).setup(app);
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}
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});
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console.log('Routes added:');
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addedRoutes.forEach(route => console.log('\t' + route));
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}
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/**
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* Setup the routes for the application
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*
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* @param app The Express app to add the routes to
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*/
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async setup(app: Application) {
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console.log('Setting up routes...')
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await this.setupControllers(app);
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}
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}
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