aasm_actionable is a Rails extension that helps factor out boilerplate state and authorization conditionals from view code. Using pundit for authorization, it allows developers to write partials for user actions that are automatically displayed to the user if the model is in an appropriate state, and the user has sufficient permissions.
aasm_actionable to your Gemfile, and run Bundler to install it. You will also want to install Pundit, as described in the Pundit documentation.
Each action that aasm_actionable may display requires the developer to provide three things:
- An event with the same name as the desired action, ex.
- A method on the pundit policy for the model on which the action is to be performed, ex.
- A partial for the model with the same name as the action, ex.
Additionally, you may wish to create a controller method and route to handle the action being performed. By convention, the controller method should have the same name as the action, ie.
do_action for the example above.
Once you have provided one or more actions for a model, you can render a model instance's available actions by including
AasmActionable::ControllerMixin in your controller, and adding
<%= render_state_actions my_instance %> in your view. The default template uses styles and code from Bootstrap 3, so you should either ensure that it is included in your application, or change the default template (see Custom Rendering below.)
Consider the following contrived Order model (in
app/models/order.rb) for a (trivial) online store:
class Order < ActiveRecord::Base include AASM aasm do state :new, initial: true state :processing state :shipping event :confirm do transitions from: :new, to: :processing end event :dispatch do transitions from: :processing, to: :shipping end end end
Suppose that users in an inventory tracking role manually confirm an order by double-checking if the item is in stock, while users in shipping are responsible for marking an order as dispatched. We would like to render appropriate actions on a view of the order, depending on the order's state and the role that the user occupies. Confirmation does not add any new information to the order, but dispatching the order requires a shipping number.
First, we need to define an policy to describe which users can perform which actions. In
app/policies/order.rb, we create a new
OrderPolicy class, and define appropriate
class OrderPolicy < ApplicationPolicy # ... other default policy methods (ex. show?) omitted for conciseness. def confirm? user.in_role? :inventory end def dispatch? user.in_role? :shipping end end
Next, we add methods to the order controller to handle these actions, along with the mixin:
class OrderController < ApplicationController include AasmActionable::ControllerMixin # ... other controller methods omitted ... def show @order = find_order authorize @order end def confirm @order = find_order authorize @order if order.confirm! redirect_to order else # ... handle the error and re-render the order page ... end end def dispatch @order = find_order authorize @order dispatch_params = params.require(:order).permit(:shipping_number) order.assign_attributes(dispatch_params) if order.dispatch! redirect_to order else # ... handle the error and re-render the order page ... end end private def find_order Order.find(params[:id]) end end
(You may want to consider using responders or a similar library to cut down on boilerplate in your custom controller methods.)
We must also add the new actions to
# ... other routes omitted ... resources :orders do member do post 'confirm' post 'dispatch' end end # ...
Next, we create a partial for each action. For example, for the dispatch action we might write the following
<% form_for @order, url: dispatch_order_path, method: :post do %> <div> <%= f.label :shipping_number %>: <%= f.text_field :shipping_number %> </div> <%= f.submit "Dispatch" %> <% end %>
Finally, we render the actions in the order view by adding
<%= render_state_actions @order %> to
The default template for
aasm_actionable can be customized as necessary. Run
rails g aasm_actionable:views to copy the template to app/views/aasm_actionable/_list.html.erb, and edit it as required.