Direct template loading in AngularWebpackPlugin results in empty component templates

packages/ngtools/webpack/src/resource_loader.ts の、レポートでリンクされているリソース読み込みロジックから始め、次に ng-webpack595 ブランチと ng-webpack598 ブランチを使って動作を再現します。dist/repro-webpack-template/main.js の AppComponent_Template を調べて、directTemplateLoading=false のビルド出力を検証します。処理されたテンプレートが空ではなくなり、変換された "hello you" の内容が引き続き含まれていれば完了です。

Command

build

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

18.3.0

Description

A bugfix in webpack 5.96.0 has broken direct template loading.
https://github.com/webpack/webpack/issues/19235#issuecomment-2688250063

When using webpack 5.96.0 or higher, if you set the directTemplateLoading option to false in the AngularWebpackPlugin, component templates end up being empty.

Note: I've said that this is a regression even though technically nothing in the Angular CLI has changed, however if you are updating the Angular CLI regularly, you are probably also updating webpack regularly, so you will encounter this bug.

Minimal Reproduction

Start with this repository: https://github.com/reduckted/repro-webpack-template

This is the setup:

• Contains AppComponent that has a template with the content "hello world".
• A custom Angular builder is used to modify the webpack configuration and set AngularWebpackPlugin.options.directTemplateLoading to false.
• A custom loader is to the webpack configuration that replaces all occurrences of "world" with "you" in HTML files.

When this works, the AppComponent's template will end up containing "hello you".

Start by cloning the repository:

git clone https://github.com/reduckted/repro-webpack-template.git
cd repro-webpack-template

Switch to the ng-webpack595 branch (this uses webpack@5.95.0). and build:

git checkout ng-webpack595
npm i
npm run build

Open dist/repro-webpack-template/main.js and search for "AppComponent_Template". You will see that it looks like this:

template: function AppComponent_Template(rf, ctx) {
  if (rf & 1) {
    _angular_core__WEBPACK_IMPORTED_MODULE_0__["ɵɵtext"](0, "hello you\n");
  }
},

This works correctly and has replaced "world" with "you".

Now switch to the ng-webpack598 branch (this uses webpack@5.98.0). and build:

git checkout ng-webpack598
npm i
npm run build

Open dist/repro-webpack-template/main.js again and search for "AppComponent_Template". You will see that it looks like this:

template: function AppComponent_Template(rf, ctx) {},

The template is completely empty.

Exception or Error

Your Environment

_                      _                 ____ _     ___
    / \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|
   / △ \ | '_ \ / _` | | | | |/ _` | '__|   | |   | |    | |
  / ___ \| | | | (_| | |_| | | (_| | |      | |___| |___ | |
 /_/   \_\_| |_|\__, |\__,_|_|\__,_|_|       \____|_____|___|
                |___/
    

Angular CLI: 19.2.0
Node: 22.13.1
Package Manager: npm 11.1.0
OS: win32 x64

Angular: 19.2.0
... animations, cli, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router

Package                         Version
---------------------------------------------------------
@angular-devkit/architect       0.1902.0
@angular-devkit/build-angular   19.2.0
@angular-devkit/core            19.2.0
@angular-devkit/schematics      19.2.0
@ngtools/webpack                19.2.0
@schematics/angular             19.2.0
rxjs                            7.8.2
typescript                      5.7.3
zone.js                         0.15.0

Anything else relevant?

As @alexander-akait says here: https://github.com/webpack/webpack/issues/19235#issuecomment-2688250063

it was a bug fix in 5.96.0 and unfortunately your code relied on buggy behavior.

Thankfully, the fix is really simple, and @alexander-akait even provided an example of how to fix it. ❤️

This:
https://github.com/angular/angular-cli/blob/cb078c276861ce6fb6aaebc589b3c44fcb854c38/packages/ngtools/webpack/src/resource_loader.ts#L129

Needs to change to:

return `data:application/javascript,export { default } from "${filePath}?${NG_COMPONENT_RESOURCE_QUERY}";`;