Get all classes/constructors by given @decorators

Question

Hi all I am wonder if that is possible get all classes that have given decorator javascript/typescript.

I have class for example

@mydecorator
class SomeClass1{
}

and somewere else in module

@mydecorator
class SomeClass2{
}

then in other module in runtime i would like to get all classes or constructors that have decorator @mydecorator ... I am afraid that this is not possible :(

export function getaAllClassesByDecorator(decorator:string){
... return constructor or something that  i am able to call static method 
}

I was look for elegant way how to globally register class and than create. Something like dependency pattern. — Ivan Mjartan, Sep 22 '16 at 06:42
Yes, but i am developing mobile web i was looking for some general hamburger menu for each view. So my idea is add label PATH to each view/component than in hamburger menu component get all classes with attribute Path and generate menu tree structure. — Ivan Mjartan, Sep 22 '16 at 07:04
Maybe this helps: https://stackoverflow.com/questions/31618212/find-all-classes-in-a-javascript-application-that-extend-a-base-class/68470454#68470454 — Denis Giffeler, Jul 26 '21 at 07:03

score 12 · Accepted Answer · answered Sep 21 '16 at 19:13

12

You need to "register" all classes that uses @mydecorator somewhere. This register logic should be implemented in @mydecorator. For example:

export const registeredClasses = [];
export function mydecorator() {
     return function(target: Function) {
          registeredClasses.push(target);
     };
}

@mydecorator()
class SomeClass1{
}

@mydecorator()
class SomeClass2{
}

Now you can get all registered classes in the registeredClasses array

answered Sep 21 '16 at 19:13

pleerock

18,322
16
103
128

This approach is what i am looking for ... if that will work ... you made my day! Tomorrow i am going to check it :-) thx – Ivan Mjartan Sep 21 '16 at 19:18
take a look on my repos on github there are more complex examples how to use decorators – pleerock Sep 22 '16 at 04:56
2

Will that work? If the classes decorated by this decorator are never referenced directly they will not be registered, because the decorators will never be executed. Am I wrong? – BrightShadow Oct 07 '21 at 08:40
@BrightShadow I am going through this right now and I think I am in the safe boat. The decorator function is not triggering if the classes are in separate modules. In which case I have to import the classes with side effects only at which point we might use plain old registration. I guess I was looking to implement a Java Spring like setup with decorators. – Sayak Mukhopadhyay Oct 10 '21 at 16:20
2

not work if the class not be called . – viola Dec 09 '21 at 11:28

score 0 · Answer 2 · answered Sep 21 '16 at 19:13

You can't do that "automatically", but you can create a registry with said classes.
Then inside your decorator function you add these classes:

const REGISTRY: { [name: string]: any } = {};

function mydecorator(constructor) {
    REGISTRY[constructor.name] = constructor;
}

Then you can query this REGISTRY and know who used this decorator.

Get all classes/constructors by given @decorators

2 Answers2