Angular 6: "Cannot read property 'CLASS_TO_PLAIN' of undefined" when using the buildOptimizer

[realmar]

Hey all!

I'm using class-transformer in my angular app. I recently upgraded the project to Angular 6 and class-transformer started throwing the following exceptions when transforming from class to plain and from plain to class:

// class to plain
Cannot read property 'CLASS_TO_PLAIN' of undefined

// plain to class
Cannot read property 'PLAIN_TO_CLASS' of undefined

I noticed that those issues only occur when enabling the buildOptimizer: true in angular.json. I would appreciate any help on the matter!

[creativec0de]

i have the same problem too

[realmar]

This is an issue with the angular build-optimizer and has been discussed here. As per this comment, the issue should be fixed. However, it seems like there is a regression in the full release of v6 which causes the enums to be stripped out again:

• [6.0.0 Regression] build-optimizer breaks exports angular/angular-cli#10655
• ng build ---prod with "optimization: true" causes browser error. angular/angular-cli#10658

A workaround is described here

I have forked class-transformer and have fixed the issue there by just using strings for the TransformationType enum: (I also moved this enum to a separate file and removed the duplicate definition of it in index.ts)

export enum TransformationType {
    PLAIN_TO_CLASS = "0",
    CLASS_TO_PLAIN = "1",
    CLASS_TO_CLASS = "2"
}

If you would like I can open a PR with the changes, however I don't know if that would be fitting as the described behavior is a bug in angular and not in class-transformer. You can see the changes I made here.

[realmar]

This issue has now been fixed in v6.0.1 of the angular devkit (angular/devkit@959826b). Closing this issue.

[NoNameProvided]

Thanks for the clear explanation for the future readers.

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