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In Angular View Engine, there are two kinds of decorator inheritance: 1) both the parent and child classes have decorators This case is supported by InheritDefinitionFeature, which merges some fields of the definitions (such as the inputs or queries). 2) only the parent class has a decorator If the child class is missing a decorator, the compiler effectively behaves as if the parent class' decorator is applied to the child class as well. This is the "undecorated child" scenario, and this commit adds a migration to ngcc to support this pattern in Ivy. This migration has 2 phases. First, the NgModules of the application are scanned for classes in 'declarations' which are missing decorators, but whose base classes do have decorators. These classes are the undecorated children. This scan is performed recursively, so even if a declared class has a base class that itself inherits a decorator, this case is handled. Next, a synthetic decorator (either @Component or @Directive) is created on the child class. This decorator copies some critical information such as 'selector' and 'exportAs', as well as supports any decorated fields (@Input, etc). A flag is passed to the decorator compiler which causes a special feature `CopyDefinitionFeature` to be included on the compiled definition. This feature copies at runtime the remaining aspects of the parent definition which `InheritDefinitionFeature` does not handle, completing the "full" inheritance of the child class' decorator from its parent class. PR Close #33362 |
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| .. | ||
| migration.ts | ||
| missing_injectable_migration.ts | ||
| README.md | ||
| undecorated_child_migration.ts | ||
| undecorated_parent_migration.ts | ||
| utils.ts | ||
ngcc migrations
There are some cases where source code needs to be migrated before ngtsc can compile it correctly.
For example, there are cases where ngtsc expects directives need to be explicitly attached to classes, whereas previously they were not required.
There are two ways this can happen:
- in a project being developed, the code can be migrated via a CLI schematic.
- in a package already published to npm, the code can be migrated as part of the ngcc compilation.
To create one of these migrations for ngcc, you should implement the Migration interface and add
an instance of the class to the DecorationAnalyzer.migrations collection.
This folder is where we keep the Migration interface and the implemented migrations.
Each migration should have a unit test stored in the ../../test/migrations directory.