Suman Kumar

Posted on Jan 31, 2023 • Updated on Jun 15, 2023

Angular Workspace 🏭

#angular #javascript #typescript #tutorial

If you want to manage multiple Angular Sub-Projects in one Main Project then Angular Workspace (a.k.a Mono-repo Pattern) is what you are looking for.

What's the use ? 🤔

You can create multiple projects that share the same workspace instead of having one workspace for each project, that would mean having one node_modules folder across projects.

What are we going to accomplish❓❓

An important note before we proceed any further, each Angular Application is an individual / independent SPA.

That means admin-app / ticketing-app should be build & deployed as separate applications. In local, ng serve admin-app / ng serve ticketing-app should be used.

Pre-Requisites

NodeJS
Angular CLI
Typescript

⏳ Let's ~~get our hands dirty~~ code

Creating an empty workspace

Create an Angular application with NO scaffolded files.

ng new main-app --create-application=false

main-app serves as a place holder for other Sub-Projects, without any actual code in it.

What value did `--create-application=false` add ?

If ng new main-app is used, the src folder contains the source code for default app. And angular.json contains a property called defaultProject to customize our default project.

Creating application(s)

Creating 2 independent Angular application's within the main-app workspace

ng generate application admin-app --routing=false --style=scss

ng generate application ticketing-app --routing=false --style=scss

Creating library

Creating new library within the main-app workspace :

ng generate library logging-lib

Use ng generate --help to know what other option(s) are available.

All application(s) and libraries created inside the workspace will be added under projects folder, by default. Which can be overridden during the creation process :

ng generate application ticketing-app --project-root=custom-proj-root

Below are the changes added to main-app workspace :

angular.json file will have 3 project definition(s)
- admin-app & ticketing-app with "projectType" as application
- logging-lib with "projectType" as library
Main workspace package.json will have new devDependency added ng-packagr
tsconfig.json will have new entry paths, pointing to dist or build destination of library .

When we import an entity (component / service) from library, here it is logging-lib, inside applications like admin-app or ticketing-app, Angular will look up for requested imports within the application dir if not found then will look into build destination mapped to paths in tsconfig.json

{
  "compileOnSave": false,
  "compilerOptions": {
    "baseUrl": "./",
    "paths": {
      "logging-lib": [
        "dist/logging-lib"
      ]
    }
  }
}

With the help of Angular CLI we have added a workspace, a library & 2 Single Page application(s)

Now lets take a look at some important files under projects/logging-lib

main-app
├── projects/
│   └── logging-lib/
│       ├── src/
│       │   ├── lib/                     # (1)
│       │   │   ├── logging-lib.component.ts
│       │   │   ├── logging-lib.module.ts
│       │   │   └── logging-lib.service.ts
│       │   └── public-api.ts            # (2)
│       ├── ng-package.json              # (3)
│       └── package.json                 # (4)
├── angular.json
├── package.json
└── tsconfig.json

Now let's go into details of some files:

Library Code (1)
This folders contains the code of the library, currently a module, component and service. This is the main and only entry point of our library right now.
Public API (2)
The file contains the public API of the library. It exports all members that should be available to the outside world. That's the Angular Module, component and service inside the src/lib/ folder.
ng-package.json (3)
The file contains the configuration for ng-packagr. It specifies the path of the build output and the entry file which points to public-api.ts.
package.json (4)
This is the package.json of your library (not to be confused with the package.json of our Angular workspace in the root folder). Here you specify the name, version and dependencies of your library.

Our objective is to create library & use it across application(s)

As the name indicates we shall create a simple logger service & try to use it across application(s)

New library structure after cleaning up :

main-app
├── projects/
│   └── logging-lib/
│       ├── src/
│       │   ├── lib/                     
│       │   │   ├── logger.service.ts
│       │   │   └── logging-lib.module.ts
│       │   └── public-api.ts
│       ├── ng-package.json
│       └── package.json
├── angular.json
├── package.json
└── tsconfig.json

// File Name : logger.service.ts
import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class LoggerService {

  constructor() { }

  log(value: string) {
    console.log(`Logging from Logger Service`);
    console.log(value);
  }
}

// File Name : public-api.ts
/*
 * Public API Surface of logging-lib
 */

export * from './lib/logger-service';
export * from './lib/logging-lib.module';

Lets build logging-lib project, using below command :

ng build logging-lib --watch

If the build is through without any errors, we can use our library service inside application(s).

File Structure after library build :

main-app
├── dist/logging-lib
├── node_modules/
├── projects/
├── angular.json
├── package.json
└── tsconfig.json

One super helpful command that i found in Angular CLI is to use generate command with --dry-run flag.

ng generate component <path-to-create-component> --project admin-app --dry-run

ng generate service <path-to-create-service> --project logging-lib --dry-run

--dry-run flag will not make any changes to file structure but will show where the new generated files are going to be added.

Now let's make final change to consume our library service inside application

main-app
├── projects/
│   └── admin-app/
│       ├── src/
│       │   ├── app/                     
│       │   │   ├── app.component.ts
├── angular.json
├── package.json
└── tsconfig.json

// File Name : app.component.ts

import { Component, OnInit } from '@angular/core';
import { LoggerService } from 'logging-lib';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss']
})
export class AppComponent implements OnInit{
  title = 'admin-app';

  constructor(private loggerService: LoggerService) {}

  ngOnInit(): void {
    this.loggerService.log(this.title);
  }

}