Reflect
Get Started
Create and export decorators
At the very first beginning, we create two decorators, one of which is a class decorator and the other is a method decorator, as follows by using DecoratorGenerator
. We can save some fields if needed. Those fields are named context
in ts-reflect
and can be accessed when decorators are applied. Notice that function myMethodDecorator
accepts a parameter label
and then is passed to context. Users can customize the value of the label
when applying this decorator.
// create.ts
import { DecoratorGenerator, getClass, Zone } from '../src/main'
// create a zone and a decorator generator
export const myZone = new Zone()
export const DG = new DecoratorGenerator(myZone)
// create a context for your class decorator
export type MyClassDecoratorContext = { owner: string }
// create a context for your method decorator
export type MyMethodDecoratorContext = { label: string }
// create a class decorator
export const MyClassDecorator = function (): ClassDecorator {
return DG.generateClassDecorator({
// saves some fields
owner: 'James',
})
}
// create a method decorator
export const MyMethodDecorator = function (label: string): MethodDecorator {
return DG.generateMethodDecorator({ label })
}
Apply decorators and get context
We apply the decorators as follows. After a decorated class is loaded, its corresponding reflector can be obtained by the classContainer
. Use getContext
to access the context we save when creating the decorator. We can also obtain the reflector of the method myMethod
. Similar operations of getting and setting the context of all kinds of reflectors are the same.
Note that in TypeSrcipt, decorators (as functions) will be called when the generated JavaScript file is imported (or required). They will not be invoked again at the second time of importing (or requiring).
// apply.ts
// apply decorators to your class
@MyClassDecorator()
class MyClass {
@MyMethodDecorator('my_label')
public myMethod() {
// some codes
}
}
it('Simple test.', function () {
// get class context
const myClassReflector = getClass<MyClassDecoratorContext>(MyClass)
const owner = myClassReflector!.getContext(myZone, 'owner')
expect(owner).toBe('James')
// get method context
const myMethodReflector = myClassReflector!.getMethod<MyMethodDecoratorContext>('myMethod')
const label = myMethodReflector!.getContext(myZone, 'label')
expect(label).toBe('my_label')
})