Question

This is my first question here, though I’m frequent visitor. I tried to find answers on my own to this but no joy.

So, I have a class in coffescript (Rails 3.1) like this:

root = global ? window

class root.CTimelineGraph
  constructor: (div, @w, @nw, @table_name) ->
    @columnNames = ""
    @dbReadTable(@table_name)
    ..

dbReadTable: (table_name) ->
    if table_name == "SOMETABLE" then @dbReadTableA1()

dbReadTableA1: ->
    sipa = ""
    $.ajax
      async: false
      type: "GET"
      url: "ajax/getcolumnnames"
      dataType: 'json'
      success: (data) ->
        sipa = data
    @columnNames = sipa

My question is, how can I populate @columnNames (declared in the constructor) with the data that I get back from ajax/getcolumnnames controller? I’m using third variable sipa to get data out of success function. Am I doing this wrong?

The code I posted is working. I’m asking the question because I intend to have many instances of this class all calling dbReadTable a lot.

Thanks.

Answer 1

Here’s a better way, without the extra variable:

dbReadTableA1: =>
  $.ajax
    async: false
    type: "GET"
    url: "ajax/getcolumnnames"
    dataType: 'json'
    success: (data) =>
      @columnNames = data

The key is the double arrow which binds this to your class instance in the success callback, which makes @columnNames available inside the function. This also assumes that dbReadTableA1 is declared as a member function in the class.