[Angular] [bug] Automatic component declaration for Angular not working with `forRoot`

Describe the bug One of the last Storybook releases introduced a new behavior for NgModules where Storybook only declares components dynamically if they were not declared already inside of an imported NgModule (see #6666 - Thanks to @MaximSagan for his awesome work!).

This new behavior also introduces an error with NgModules imported by a static forRoot method which is a really common pattern for Angular apps:

TypeError: Cannot read property ‘value’ of undefined

I already traced the error down to the line 60 in angular helpers. I would suggest to check the importItem for an existing key ngModule to identify forRoot-imports.

Click to expand diff

  const extractNgModuleMetadata = (importItem: any): NgModule => {
+ const target = importItem && importItem.ngModule ? importItem.ngModule : importItem;
  const decoratorKey = '__annotations__';
  const decorators: any[] =
    Reflect && Reflect.getOwnPropertyDescriptor
-     ? Reflect.getOwnPropertyDescriptor(importItem, decoratorKey).value
-     : importItem[decoratorKey];
+     ? Reflect.getOwnPropertyDescriptor(target, decoratorKey).value
+     : target[decoratorKey];

    if (!decorators || decorators.length === 0) {
      return null;
    }

    const ngModuleDecorator: NgModule | undefined = decorators.find(
      decorator => decorator instanceof NgModule
    );
    if (!ngModuleDecorator) {
      return null;
    }
    return ngModuleDecorator;
  };

I can provide a PR with this fix if you’re fine with this change.

To Reproduce Repo: https://github.com/pascaliske/form-elements Branch: feature/v8 Problematic line: https://github.com/pascaliske/form-elements/blob/feature/v8/.storybook/config.ts#L24 Steps to reproduce the behavior:

1. Clone repo at branch feature/v8
2. Start storybook with yarn run build && yarn run storybook
3. See error in almost every story

Expected behavior Storybook can extract Metadata from imported NgModules both with or without forRoot.

Screenshots n/a

Code snippets n/a

System:

• OS: MacOS 10.14.5
• Device: Macbook Pro 2019
• Browser: chrome
• Framework: angular
• Addons: notes, knobs, actions, links
• Version: v5.1.8

Additional context n/a

[pascaliske]

The bugfix from the PR works as expected. Thanks! 🙂

[shilman]

Ooh-la-la!! I just released https://github.com/storybookjs/storybook/releases/tag/v5.2.0-beta.9 containing PR #7224 that references this issue. Upgrade today to try it out!

You can find this prerelease on the @next NPM tag.

Closing this issue. Please re-open if you think there’s still more to do.