AOT compiler - include lazy loaded external module

Question

I am trying to include external module (hosted in git/npm repository) as lazy-loaded module in my Angular application.

I am compiling my external module with ngc compiler:

node_modules/.bin/ngc -p tsconfig-aot.json

This is how my compiler config looks:

{
  "extends": "./tsconfig.json",
  "compilerOptions": {
    "baseUrl": "src",
    "declaration": true,
    "outDir": "./release/src"
  },
  "files": [
    "./src/index.ts"
  ],
  "angularCompilerOptions": {
    "genDir": "release",
    "skipTemplateCodegen": true,
    "entryModule": "index#ExternalModule",
    "skipMetadataEmit": false,
    "strictMetadataEmit": true
  }
}

And in my main app I am lazy loading given module:

RouterModule.forRoot([
      { path: '', component: HomeComponent, pathMatch: 'full'},
      { path: 'lazy', loadChildren: './lazy/lazy.module#LazyModule'},
      { path: 'external', loadChildren: '@angular-universal-serverless/external-module/release#ExternalModule'}
])

For compilation purposes I am using @ngtools/webpack plugin.

The JIT compilation works without any problems, but AOT compilation gives me error:

ERROR in ./src/ngfactory lazy
Module not found: Error: Can't resolve '/path/to/my/project/angular-universal-serverless/src/ngfactory/node_modules/@angular-universal-serverless/external-module/release/src/index.js' in '/Users/mtreder/Documents/private/work/angular-universal-serverless/src/ngfactory'
 @ ./src/ngfactory lazy
 @ ./~/@angular/core/@angular/core.es5.js
 @ ./src/main.server.aot.ts

So I decided to check what is the output from ngc compiler (whic is called under the hood by the webpack plugin):

node_modules/.bin/ngc -p tsconfig.server.aot.json

And in fact, my module is missing in the /path/to/my/project/angular-universal-serverless/src/ngfactory/node_modules catalog.

ls src/ngfactory/node_modules/
@angular        @nguniversal        @types          idb         ng-http-sw-proxy    rxjs            typescript-collections

How can I force ngc to place given modules in the ngfactory output directory?

My main application can be found here: https://github.com/maciejtreder/angular-universal-serverless/tree/externalModule

And external module here: https://github.com/maciejtreder/angular-external-module

Answer 1

1) The first problem here is that AOT compiler doesn't compile your module(node_modules folder is excluded by default), so you have to include it in files option of your ts configs:

tsconfig.browser.json

tsconfig.server.json

tsconfig.server.aot.json

"files": [
  "./node_modules/@angular-universal-serverless/external-module/release/src/externalComponent/external.module.d.ts"
],
"include": [
  "./src/main.browser.ts",
  "./src/app/lazy/lazy.module.ts",
  "./src/app/httpProxy/http-proxy.module.ts"
]

We can't add it to includes array because typescript will exclude it

Files included using "include" can be filtered using the "exclude" property

See more details in the doc

2) Then \node_modules\@angular-universal-serverless\external-module\release\package.json should has typings field like:

"name": "@angular-universal-serverless/external-module",
"main": "./src/index.js",
"typings": "./src/externalComponent/external.module.d.ts", <=== this one

We have to use external.module.d.ts because angular doesn't create ngfactory file for index.d.ts while @ngtools/webpack plugin creates map for ContextElementDependency:

const factoryPath = lazyRoute.replace(/(\.d)?\.ts$/, '.ngfactory.ts');
// where lazyRoute === .../external-module/release/src/externalComponent/external.module.d.ts
const lr = path.relative(this.basePath, factoryPath);
this._lazyRoutes[k + '.ngfactory'] = path.join(this.genDir, lr);

If you don't want to change package.json then change loadChildren field:

{ 
  path: 'external', 
  loadChildren: '@angular-universal-serverless/external-module/release/src/externalComponent/external.module#ExternalModule'
}

Answer 2

maybe it's too late, but I hope this could help someone.

I wrote a very simple node script to be run right after npm install. It is indeed a post install script. It copies source files from node_modules into a folder under the main project. It then updates references to lazy loaded modules in the main routes file.

It worked perfectly for my team and we increased app performances very much.

The script is short and well documented, please check it out

https://gist.github.com/insanediv/8b4ebba06824a3eb8233e10287a1cdcd