activerecord GROUPed BY in batches

We are all familiar with activerecord .find_in_batches. The main idea behind it is not allowing to load thousands of ActiveRecord objects in memory which would cause tear down the server. I looked at this method and I looked at `.group` which applies GROUP BY clause. Just for fun, I thought what if I receive these “grouped_by” data in batches, something like

 scope.grouped_by_in_batches(group_by_column) do |batch, value|
  batch is an array same as we get in case of `find_in_batches`
  value is the grouped value of the column

Hence I worked on this idea, made a pull request which obliviously did not work, as this was not a common use case, thats all fine. I agree to it. Even I never got to use it till date. However in attempt to do so, I really enjoyed writing test cases for it, getting interacted with a couple of ruby/rails expertise. Feeling happy about it.

Highlight changes being made on ActiveRecord object inside email

I simply needed one helper method which would help me highlight changes being made on any ActiveRecord object inside email. Below is one example of that I have come up with and would like to extend it in my future projects too.

It gave me some insights into ActiveRecord::Base#previous_changes and ActiveRecord::Base#reflections. Nice to learn such ActiveRecord features.

samg/diffy also helped me out decorating text changes

Screenshot from 2014-01-16 13:50:15

Adding to my MailerHelper

activeadmin cool tweaks

tweak 1: Make some column quick-editable on the index list page


Ok… so I want to be quickly able to edit few names, here on the same list page, something like below


Thats simply great!

Now it makes me quickly update any name there itself on the list page, <enter> will make it, <escape> will ignore it, and <tab> will move to the next one. awesome.

And to make it work I just need to have one line of code change

All I need to say is `editable_test_column`, and its done.

And here how it works, you will need to define a couple of things

You need to define editable_text_column, this you could place inside app/admin/lib/

Then you will need to add some javascript …

and some css stuff

Thats it.

Next, I would love to quickly alter article type say having a dropdown there to save my time

tweak 2: quick editable dropdowns on list page


Ohh, now this is again great!   … no? It actually updates the article type on value change. nice.

Let see the code behind

and to define `column_select`

CustomHelper is one of my helper modules that really helps me render dropdown the way I need, and provides me some nice options, one may choose to use the default rails select helpers

Then you need some javascript


I do have worked out several more tweaks like toggle button for boolean column, show/hide columns on the list page, auto-populate/suggest feature for string filters, one can make use ActiveAdmin icons too, then for one of my requirements I have set up the whole custom header and a dozens of custom pages. I would easily say that ActiveAdmin is just simple and awesome, one can really customize it to the extreme, the code structure will allow you to imagine and implement a number of custom scenarios.

google “chef-solo rails deploy git submodule checkout branch sha”

Working with chef resource deploy, faced several issues with Git provider, for examples

– enable_submodule does not work properly
– it does not get the latest code from submodules
– it does not allow you to choose specific branch and sha of any submodule
– in fact for main repo it does not allow you to switch to any specific branch and sha
– for some reason it says branch=version, who knows why ….

I tried correcting all above, and below is one of my examples, its working for me

dealing with concerns

Taking care of concerns, my views are

They are meant not to have large/GOD classes

They are not specific to ActiveRecord

They are there to help us out find out dependencies easier

They should not be dependent on each other, if module A has concern :b, then there should exist paths “root/a.rb” and “/root/a/b.rb“. Though this we ourself have to make sure about concerns path by writing additional code at initialization

I always willing to write clean and neat code, and have end up maintaining my concerns the following ways

  1. Reopening Class
  2. Include Module
  3. Extend ActiveSupport::Concern

I do have one doubt though, out of 3 approaches, which one is good for faster execution?

DRYing if @current_user.nil?

While working on one of rails applications, as I usually tend to check whether user is logged in, specially in views as follows

<% if @current_user.nil? %>
  <a href='url to login page'>
<% else %>
  <a href='some url where logged in user have access'>
<% end %>

And over some period I found this pattern repeating everywhere.

I thought of DRYing it, I wanted to have a kind of before_filter for every link that appear on the page, every link should go for login if that page or feature require user entity. and this should be handled by a common thing, similar to before_filter: login_require, on server side. I intend to achieve similar in views. A while back when I read up about html5 custom data attribute, and unobtrusive javascript etc, referring to them, I got one idea as described below, though it is not something that I am making use of custom data attribute exactly, but I found this idea useful and working. May be someone would have good suggestions here for me.

I will put any link which require user login as follows

<a href="/feature/page/" login-require >Feature</a>

And then I will have my after_load.js which will have the following event binding

jQuery('a[login-require]').bind('click', function() {
  <% if @current_user.nil? %>
    return false;
  <% else %>
    return true;
  <% end %>