如何在Coffeescript inhertiance中从父级访问子模型静态

Question

I have the following BaseModel class

namespace 'Models', (exports) ->
  class exports.BaseModel
    toJSON: =>
      if @jsonProperties? then ko.toJSON( @, @jsonProperties() ) else null

Then my Profile class that inherits the BaseModel class

namespace 'Models', (exports) ->
  class exports.Profile extends exports.BaseModel
    constructor: ( @options ) ->
      @FirstName = ko.observable( @options.FirstName )
      @LastName = ko.observable( @options.LastName )

  @jsonProperties: -> 
    return [ "FirstName", "LastName" ]

This allows me to call something like the following

profile = new Models.Profile
  FirstName: 'blah'
  LastName: 'blah'   

profile.toJSON()

However within the base model @jsonProperties is undefined because it's kind of like a static function on the class type. The reason I want this is so that I can reference it in other classes like so Models.Profile.jsonProperties()

Is is possible for me to get access to something like this from within the BaseModel?

---

EDIT: Adding in a placeholder fix until I come up with something better

I've done the following to get it working but I'd rather not have to repeat this line in every Model that I create, it seems like there should be a generic way to do this from the BaseModel.

namespace 'Models', (exports) ->
  class exports.Profile extends exports.BaseModel
    constructor: ( @options ) ->
      @jsonProperties = Models.Profile.jsonProperties

Answer 1

If I understood what you are trying to achieve, you can fix it by defining jsonProperties as both a "static" Class method and an instance method. Here is a simplified code (don't have access to the namespace util and knockout):

class BaseModel
  toJSON: =>
    if @jsonProperties? 
      for value in @jsonProperties()
        @[value]
    else
      null

class Profile extends BaseModel
  constructor: ( @options ) ->
    @FirstName = @options.FirstName
    @LastName = @options.LastName

  @jsonProperties: -> 
    return [ "Class FirstName", "Class LastName" ]

  jsonProperties: -> 
    return [ "FirstName", "LastName" ]

prof = new Profile
  FirstName: 'Leandro'
  LastName: 'Tallmaris'   

alert(prof.toJSON());

alert(Profile.jsonProperties());

The first alert should give you Leandro, Tallmaris , while the second Class FirstName, Class SecondName .