javascript doesn't seem to be getting data from rails source

Question

I am using dataTables to display a nice table to display various information. The javascript successfully sends poll requests to the database/webserver, however the javascript doesn't seem to be getting any current data.

Here is my controller

class CommentsController < ApplicationController
  before_filter :authenticate_user!
  before_filter :get_current_user

  # GET /comments
  # GET /comments.json

  def get_current_user
    @user=current_user
  end

  def index
    @comments = @user.comments

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @comments }
    end
  end

View:

<h1>Listing comments</h1>

<table id="comments_id" class="display">
<thead>
  <tr>
    <th>String</th>
    <th>secondString</th>
    <th></th>
    <th></th>
  </tr>
</thead>
<tbody>
</tbody>
</table>

<br />

<%= link_to 'New Comment', new_comment_path %>
<h1>Listing comments</h1>

<table id="comments_id" class="display">
<thead>
  <tr>
    <th>State</th>
    <th>Environment</th>
    <th>dns</th>
    <th></th>
    <th></th>
    <th></th>
  </tr>
</thead>
<tbody>
</tbody>
</table>

<br />

<%= link_to 'New Comment', new_comment_path %>
<h1>Listing comments</h1>

<table id="comments_id" class="display">
<thead>
  <tr>
    <th>State</th>
    <th>Environment</th>
    <th>dns</th>
    <th></th>
    <th></th>
    <th></th>
  </tr>
</thead>
<tbody>
</tbody>
</table>

<br />

<%= link_to 'New Comment', new_comment_path %>

comments.js:

function InitOverviewDataTable()
{
  oOverviewTable =$('#desktops_id').dataTable(
  {
    "bPaginate": true,
    "bJQueryUI": true,  // ThemeRoller-stöd
    "bLengthChange": false,
    "bFilter": false,
    "bSort": false,
    "bInfo": true,
    "bAutoWidth": true,
    "bProcessing": true,
    "iDisplayLength": 10,
    "sAjaxSource": 'desktops'
  });
}

function RefreshTable(tableId, urlData)
{
  $.getJSON(urlData, null, function( json )
  {
    table = $(tableId).dataTable();
    oSettings = table.fnSettings();

    table.fnClearTable(this);

    for (var i=0; i<json.aaData.length; i++)
    {
      table.oApi._fnAddData(oSettings, json.aaData[i]);
    }

    oSettings.aiDisplay = oSettings.aiDisplayMaster.slice();
    table.fnDraw();
  });
}

function AutoReload()
{
  RefreshTable('#desktops_id', 'desktops');

  setTimeout(function(){AutoReload();}, 3000);
}

$(document).ready(function () {
  InitOverviewDataTable();
  setTimeout(function(){AutoReload();}, 3000);
});

I am seeing the correct queries being pushed through on the database side:

Started GET "/comments" for 127.0.0.1 at 2013-01-22 18:46:16 -0500
Processing by CommentsController#index as JSON
  User Load (0.5ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
  Comment Load (0.4ms)  SELECT "comments".* FROM "comments" WHERE "comments"."user_id" = 1
Completed 200 OK in 6ms (Views: 3.2ms | ActiveRecord: 0.9ms)

However on firefox's web console I am seeing that as it polls, no data is being retrieved...and when the dataTable is stuck at "loading data"

[19:04:37.395] GET http://localhost:3000/comments?_=1358899476292 [HTTP/1.1 200 OK  38ms]
[19:04:39.344] GET http://localhost:3000/comments [HTTP/1.1 304 Not Modified  15ms]
[19:04:42.360] GET http://localhost:3000/comments [HTTP/1.1 304 Not Modified  18ms]

Thanks for your help

Can you provide a console log dump of the `json` variable? Does it contain the key `aaData`? — mccannf, Jan 23 '13 at 00:23
I ran firebug and found this........... TypeError: json.aaData is undefined [Break On This Error] for (var i=0; i — Pinpin, Jan 23 '13 at 03:17
Have a look at this question, particularly the one with the fnReloadAjax() definition: http://stackoverflow.com/questions/5566541/how-to-reload-the-datatablejquery-data — mccannf, Jan 23 '13 at 20:38

Dirk von Grünigen · Answer 1 · 2013-11-01T14:16:12.730

The problem is that the JSON data coming from your server doesn't have a value for the key aaData because you're serializing ActiveRecord objects.

I would generally change the way you use the DataTable plugin because it looks like you're using internal APIs (e.g. _fnAddData), which is a little bit nasty.

Instead I would recommend the approach which Ryan Bates shows in its RailsCast #340 on Datatables. This way worked really well for me and I never had problems with it.

javascript doesn't seem to be getting data from rails source

1 Answers1