#active_admin

activeadmin - The administration framework for Ruby on Rails applications.

Active Admin provides a very useful back-end framework for website administration and it is stocked with useful features.

Like all software, it does have a few issues. Out of the box, its stylesheets conflict with other stylesheets called in application.css using the sprockets require_tree directive.

When using Active Admin with a Rails 4 application that runs in a Heroku production environment, bugs arise in asset compilation. Often the Active Admin stylesheets are not compiled in production.

Here are some steps to help you remedy these problems:

1. Inside of environments/production.rb

config.serve_static_assets = true

config.assets.compile = true

2. Inside of initializers/assets.rb

Rails.application.config.assets.precompile += %w( application.js application.css.scss active_admin.css.scss active_admin.js.coffee active_admin/print.css )

3. To remedy conflicts between ActiveAdmin stylesheets and application stylesheets you may remove the require_tree directive inside of application.css and require each stylesheet explicitly.

Alternatively, you may place active_admin.css.scss and active_admin.js in vendor/assets instead of app/assets. This prevents inclusion of Active Admin assets when the sprockets directive require_tree is used. Require_tree is the default sprockets directive in application.css for a new Rails 4 app. Putting the Active Admin assets in vendor/assets avoids this conflict.

4. After pushing to your production repository, precompile and restart the server:

heroku run rake assets:precompile

A Rails 3.2 project I'm working on uses the ActiveAdmin library to handle backend updates. It's a fantastic library.

The users had a request that when updating a resource they would stay on the edit page rather than the default redirect to the index. The solution was to override ActiveAdmin's controller update method:

    controller do

        def update

            update! do |format|

                format.html { redirect_to edit_resource_path(resource) }

            end

        end

If you're running into a problem toggling all checkboxes in index page for batch action in Active Admin you should:

1. Download jquery-migrate

2. Added it as asset and require it in active_admin.js manifest file

I have just started as a full time Frontiersman after a long 7 years of finishing off a Computer Science degree(I hope). I've been through a week and its going really well; the people are awesome and I'm learning a lot.

Something I told myself was that once I started full time I really wanted to push myself as a developer. I figured one good way to help consolidate things that I am learning is to write a weekly blog post about things I found of particular interest in the previous week. So here are what I hope are the first of many posts to come.

Bogus Gateway in Active Merchant

The first thing I want to talk about is the BogusGateway that ActiveMerchant provides. I had done some work previously with Active Merchant but this was the first time I had come across it. Basically, it gives you a gateway which allows you to test with without having to actually hit a banks api with a test account or stub out all the calls. Generally you'd set it up something like this:

module Example class Application < Rails::Application ... @@CreditCardGateway = ActiveMerchant::Billing::Gateway.new end end

Example::Application.configure do ... Gimme::CreditCardGateway = ActiveMerchant::Billing::ActualGateway.new(:login => 'RealMerchant', :password => 'password') end

Example::Application.configure do ... Gimme::CreditCardGateway = ActiveMerchant::Billing::BogusGateway.new(:login => 'TestMerchant', :password => 'password') end

You then pass it a ActiveMerchant::Billing::CreditCard object with a number of 1 for valid or 2 for invalid (anything else throws an error). You can then make calls on the gateway like you normally would. The only small issue with this is that 1 and 2 aren't valid credit card numbers so if in your method you check that the card is valid (as you should), you will need to stub the call to valid? out.

Has many through through

This is something that caught me last week. I had the following associations. 

class Airplane < ActiveRecord::Base has_many :airplane_remotes has_many :remotes, :through => :airplane_remotes end

class AirplaneRemote < ActiveRecord::Base belongs_to :airplane belongs_to :remotes end

class Remote < ActiveRecord::Base has_many :airplane_remotes has_many :airplanes, :through => :airplane_remotes end

class Battery < ActiveRecord::Base belongs_to :remotes has_many :airplanes, :through => :remotes end

If you call battery.remote.airplanes you will get the list of airplanes that are associated with its remote. If you call battery.airplanes you get an empty collection. In anything below Rails 3.1 you can't have a has many through through relationship.

Active Admin f.has_many

I also had the chance to play around with ActiveAdmin a bit last week and was very impressed with it. One thing that I was really impressed with was the nice little addition to the Formtastic form builder it has. What it allows you to do is specify a has many relationship in the following way.

ActiveAdmin.register Example do ... form do |f| f.inputs do f.input :name f.has_many :programs end f.buttons end end

This will use ajax to create new program associations without having to refresh or write any custom javascript. You need to make sure that Example accepts_nested_attributes_for :programs otherwise it won't work One slight drawback is whilst it will allow you to destroy any newly created associations, it won't allow you to destroy any pre-existing ones. Even so, I found this really neat.

As I think I've said before a lot of the topics on this blog aren't ground breaking stuff but I figure it might be useful to people who are learning like I am.

I've been mucking about with Active Admin, at times trying to bend it to my will. I've been frustrated as hell trying to get it to do some fairly simple stuff, and at times elated when I find a way to do it. The project documentation is, let's say - progressing, and sometimes the best to work things out is to delve into the innards.

I had some success today while integrating the Paper Trail gem into my project. Paper Trail adds versioning of objects. It also permits you to switch to any version at any time, and record information about the nature of the version, for instance, who made the change.

In my project I don't have a standard user, since the project is solely for administration, I have a manager model. Active Admin allows me to choose the model I want as a user object with Devise (for authentication):

# /config/initializers/active_admin.rb ActiveAdmin.setup do |config| config.authentication_method = :authenticate_manager! config.current_user_method = :current_manager end

To integrate paper_trail, I need to tell it who the current user is, by default it's looking for a method in the application controller called current_user. Since I don't have a current user, instead I have a current manager, I need to override a method called user_for_paper_trail. This is typically done in the application controller.

Active Admin provides for a way to include before, after and around filters by adding them to it's config. So I can include a before filter for the overridden method required by paper_trail in the config. This much is clear from the comments in the active_admin config file.

# /config/initializers/active_admin.rb ActiveAdmin.setup do |config| config.before_filter :user_for_paper_trail end

What I was unclear about was where to put my method definition. I can't simply put it in the ApplicationController as that is ignored by Active Admin. I assumed I had to override the admin controller in some way, and include the def block in the active_admin registration block for the model.

This is what I learned eventually, and it seems to work. I am able to wrap my method in a controller block, like this:

# /app/admin/posts.rb ActiveAdmin.register Post do controller do def user_for_paper_trail current_manager end end end