Typescript Decorator or Inheritance for additional attributes

user_1822974 0
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Say I have currently the following model structure, 

class Entity {
   id : string;
}

class HateoasEntity extends Entity{
   _links : any;
   _msgs : any;
}

class EditableEntity extends HateoasEntity{
   _new : boolean;
   _editInProgress : boolean
}

class Employee extends EditableEntity{
    name : string;
    address : string;
}

For this, Can I create custom typescript decorators to add those metadata without inheritance?

@Entity
@HateoasEntity
@EditableEntity
class Employee{
  name : string;
  address: string;
}

Is it a good way to go with decorators? Or what i am trying to achieve is bad design?

typescript2.0 angular typescript
1 Answers

You can archive the desired behavior using typescript decorators by adding required fields to the class prototype. However you'll lose the main benefit of TypeScript - typing information.

Take a look on the Intersection types:

interface EntityFields {
   id : string;
}

interface HateoasFields {
   _links : any;
   _msgs : any;
}

interface EditableFields {
   _new : boolean;
   _editInProgress : boolean
}

interface EmployeeFields {
    name : string;
    address : string;
}

type Employee = EntityFields & HateoasFields & EditableFields & EmployeeFields

This way you still have typing information and you can easily reuse fields in other places.

user_41729790
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