Using ng update with @angular-builders/custom-webpack

[wszydlak]

Describe the Bug

Currently, doing ng update will not migrate applications properly when using @angular-builders/custom-webpack. This is due to @angular/cli migrations are checking if builder target is @angular-devkit/build-angular.

This issue is related to angular/angular-cli#24741 - there are more informations.

[just-jeb]

Hey @wszydlak, thanks for bringing this up.
Undoubtedly the right way to go is to add this capability to the builder. I also assume it wouldn't be that huge of an effort if you extend Angular CLI's schematics. If you want to submit a PR, it would be most appreciated.

For the meanwhile, a tolerable workaround for those who struggle with this issue:

1. Copy @angular-builders/custom-webpack specific properties from the config JSON to some other place.
2. Replace @angular-builders/custom-webpack builder target with @angular-devkit/build-angular (while removing the @angular-builders/custom-webpack specific properties).
3. Run ng update.
4. Replace @angular-devkit/build-angular build target with @angular-builders/custom-webpack.
5. Add @angular-builders/custom-webpack specific properties back to the config JSON.

Since @angular-builders/custom-webpack is by all means an extension to @angular-devkit/build-angular, all the changes that apply to the latter also apply to the former, so they should be applied on one hand and they shouldn't hurt anything on another.