angular / angular/angular-cli

Direct template loading in AngularWebpackPlugin results in empty component templates

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#29,728 7 comments 1 reaction 0 assignees View on GitHub
area: @ngtools/webpack freq1: low severity5: regression type: bug/fix
Dominant language
TypeScript
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Description

### Command

build

### Is this a regression?

- [x] 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:

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

The template is completely empty.

### Exception or Error

```text

```

### Your Environment

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

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. :heart:

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

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

Contributor guide

Open the contributing guide

Research direction

Start in packages/ngtools/webpack/src/resource_loader.ts at the resource-loading logic linked in the report, then reproduce the behavior using the ng-webpack595 and ng-webpack598 branches. Verify the directTemplateLoading=false build output by inspecting AppComponent_Template in dist/repro-webpack-template/main.js. Done means the processed template is no longer empty and still contains the transformed "hello you" content.

Written by the indexing model from the issue text.

Assessment

Tech stack
angular, typescript, webpack
Domain
build-system
Issue type
Bug
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
52/100

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