Trouble updating nested attributes - ruby-on-rails

Question

I'm trying to build a small expense tracking app using Rails 4.1. When a user submits the expense request, it's state is marked as pending by default. The admin has to approve the request. I'm using state_machine gem to do this.
Comments are added from the expense show page using a nested_form_for like this:
<%= nested_form_for (#expense) do |f| %>
<div class="form-group">
<%= f.label :state %><br />
<%= f.collection_select :state, #expense.state_transitions, :event, :human_to_name, :include_blank => #expense.human_state_name, class: "form-control" %>
</div>
<%= f.fields_for :comments, #expense.comments.build do |comment| %>
<div class="form-group">
<%= comment.label :comment%>
<%= comment.text_area :comment, class: "form-control" %>
</div>
<% end %>
<%= f.submit "Submit", class: "btn btn-primary" %>
<% end %>
The controller looks like:
class ExpensesController < ApplicationController
def new
#expense = Expense.new
#item = #expense.items.build
#comment = #expense.comments.build
end
def show
#expense = Expense.find(params[:id])
#items = Item.where(:expense_id => #expense.id)
end
def update
#expense = Expense.find(params[:id])
if #expense.update(expense_params)
if #expense.state == "approved"
ExpenseMailer.expense_approved(#expense).deliver
flash[:notice] = "Expense Report Updated"
redirect_to expenses_path
elsif #expense.state = "rejected"
ExpenseMailer.expense_declined(#expense).deliver
flash[:notice] = "Expense Report Updated"
redirect_to expenses_path
end
else
render 'edit'
end
end
private
def expense_params
params.require(:expense).permit(:claim, :department_id, :expense_type_id, :expense_attachment, :state, :notes, items_attributes: [:id, :description, :amount, :issue_date, :_destroy], comments_attributes:[:id, :comment, :expense_id])
end
The problem is, if I add a comment without changing the state from the dropdown, I get the 'state is invalid' error and the edit page is shown. I can get past this by simply hitting the update button. But, the comments aren't created. On the other hand, if I change the state and add a comment, comments are shown without any issue.
The params value for that is:
Started PATCH "/expenses/14" for 127.0.0.1 at 2014-08-15 13:31:40 +0530
Processing by ExpensesController#update as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"MAEL2UYzos76NV6/eumHkXcpR2ge09wm6eOGQ+eEGCA=", "expense"=>{"state"=>"", "comments_attributes"=>{"0"=>{"comment"=>"vv"}}}, "commit"=>"Submit", "id"=>"14"}
The expense model with state machine looks like:
state_machine initial: :pending do
state :pending
state :approved
state :rejected
event :approved do
transition [:pending, :rejected] => :approved
end
event :rejected do
transition [:pending, :approved] => :rejected
end
end
Guess I'm making some mistake when it comes to building the comment attributes. Can someone let me know where I have to make changes?
Logger info for rejection:
Started GET "/expenses/17" for 127.0.0.1 at 2014-08-15 16:22:43 +0530
Processing by ExpensesController#show as HTML
Parameters: {"id"=>"17"}
[1m[35mExpense Load (0.2ms)[0m SELECT "expenses".* FROM "expenses" WHERE "expenses"."id" = ? LIMIT 1 [["id", 17]]
[1m[36mItem Load (0.1ms)[0m [1mSELECT "items".* FROM "items" WHERE "items"."expense_id" = ?[0m [["expense_id", 17]]
[1m[35mComment Load (0.2ms)[0m SELECT "comments".* FROM "comments" WHERE "comments"."expense_id" = ? [["expense_id", 17]]
Rendered expenses/show.html.erb within layouts/application (16.2ms)
Completed 200 OK in 45ms (Views: 42.8ms | ActiveRecord: 0.5ms)
Started PATCH "/expenses/17" for 127.0.0.1 at 2014-08-15 16:22:53 +0530
Processing by ExpensesController#update as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"MAEL2UYzos76NV6/eumHkXcpR2ge09wm6eOGQ+eEGCA=", "expense"=>{"state"=>"rejected", "comments_attributes"=>{"0"=>{"comment"=>"checking logger for rejected!"}}}, "commit"=>"Submit", "id"=>"17"}
[1m[36mExpense Load (0.2ms)[0m [1mSELECT "expenses".* FROM "expenses" WHERE "expenses"."id" = ? LIMIT 1[0m [["id", 17]]
[1m[35m (0.1ms)[0m begin transaction
[1m[36mSQL (8.1ms)[0m [1mUPDATE "expenses" SET "state" = ?, "updated_at" = ? WHERE "expenses"."id" = 17[0m [["state", "rejected"], ["updated_at", "2014-08-15 10:52:53.030676"]]
[1m[35mSQL (0.2ms)[0m INSERT INTO "comments" ("comment", "created_at", "expense_id", "updated_at") VALUES (?, ?, ?, ?) [["comment", "checking logger for rejected!"], ["created_at", "2014-08-15 10:52:53.040889"], ["expense_id", 17], ["updated_at", "2014-08-15 10:52:53.040889"]]
[1m[36m (4.2ms)[0m [1mcommit transaction[0m
Redirected to http://localhost:3000/expenses
Completed 302 Found in 24ms (ActiveRecord: 12.8ms)
Logger info for approval:
Started GET "/expenses/16" for 127.0.0.1 at 2014-08-15 16:22:30 +0530
Processing by ExpensesController#show as HTML
Parameters: {"id"=>"16"}
[1m[35mExpense Load (0.3ms)[0m SELECT "expenses".* FROM "expenses" WHERE "expenses"."id" = ? LIMIT 1 [["id", 16]]
[1m[36mItem Load (0.2ms)[0m [1mSELECT "items".* FROM "items" WHERE "items"."expense_id" = ?[0m [["expense_id", 16]]
[1m[35mComment Load (0.3ms)[0m SELECT "comments".* FROM "comments" WHERE "comments"."expense_id" = ? [["expense_id", 16]]
Rendered expenses/show.html.erb within layouts/application (167.3ms)
Completed 200 OK in 244ms (Views: 213.7ms | ActiveRecord: 1.1ms)
Started PATCH "/expenses/16" for 127.0.0.1 at 2014-08-15 16:22:41 +0530
Processing by ExpensesController#update as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"MAEL2UYzos76NV6/eumHkXcpR2ge09wm6eOGQ+eEGCA=", "expense"=>{"state"=>"approved", "comments_attributes"=>{"0"=>{"comment"=>"checking logger!"}}}, "commit"=>"Submit", "id"=>"16"}
[1m[36mExpense Load (0.2ms)[0m [1mSELECT "expenses".* FROM "expenses" WHERE "expenses"."id" = ? LIMIT 1[0m [["id", 16]]
[1m[35m (0.1ms)[0m begin transaction
[1m[36mSQL (0.5ms)[0m [1mUPDATE "expenses" SET "state" = ?, "updated_at" = ? WHERE "expenses"."id" = 16[0m [["state", "approved"], ["updated_at", "2014-08-15 10:52:41.604580"]]
[1m[35mSQL (0.5ms)[0m INSERT INTO "comments" ("comment", "created_at", "expense_id", "updated_at") VALUES (?, ?, ?, ?) [["comment", "checking logger!"], ["created_at", "2014-08-15 10:52:41.607555"], ["expense_id", 16], ["updated_at", "2014-08-15 10:52:41.607555"]]
[1m[36m (4.0ms)[0m [1mcommit transaction[0m
Redirected to http://localhost:3000/expenses
Completed 302 Found in 17ms (ActiveRecord: 5.3ms)

Answer 1

I don't know why you're getting an error, but I'll give you some ideas for the state_machine / aasm gems
--
State Machines
Since Rails is object-orientated, you have to appreciate how these state machine gems work - they are an extrapolation of the electronics method of setting up a "state machine" (to predicate finite "states" within a circuit):
What I'm trying to demonstrate with this is that by including a state machine in your application, you're actually indicating the state of an object (it's not just another attribute)
Currently, you're treating the state attribute of your Comment model as an attribute, when it can be treated as an object in itself
--
Object
Notice this functionality from the State Machine repo:
Notice how that has nothing to do with the state attribute?
I think you'd be better treating the state method as what it is - a way to influence the state_machine itself. I would do that in several ways:
Set the state "default" state in the state_machine declaration
Validate the state object using OOP principles
#app/models/expense.rb
Class Expense < ActiveRecord::Base
state_machine :state, :initial => :pending do #-> sets the state to "pending" unless specified otherwise
end
end
#app/controllers/expenses_controller.rb
Class ExpensesController < ApplicationController
def update
if #expense.approved?
...
end
end
end
--
Fix
In regards to your being unable to create a comment, I think the problem will be two-fold
Firstly, you're building your comments within the view. Apart from anything, this is bad practice (against MVC) - you'll be best building the associated objects inside your model:
#app/models/expense.rb
Class Expense < ActiveRecord::Base
def self.build id
expense = (id.present?) self.find id : self.new
expense.comments.build
return expense
end
end
This allows you to perform the following:
#app/controllers/expenses_controller.rb
Class ExpensesController < ApplicationController
def new
#expense = Expense.build
end
def edit
#expense = Expense.build params[:id]
end
end
This will basically give your nested comments form the pre-built nested objects required to fire the form for the edit & new methods (so you don't need to call #expense.comments.build in your view)
In regards to the non-saving functionality - I would certainly look at how you're saving the state attribute. I suspect it will be down to you not passing the attribute correctly (IE that you're using an incorrect value for the state param upon default submission)
I would recommend using the following:
Investigate your params from the "default" update
Does the state attribute match your model definition of the attributes?
If it does not, that will be your problem
--
UPDATE
Thanks for the update
Okay, so the problem seems to be that the state value is not being passed if it's default. I think the way to fix this will be to set a default value for the collection_select:
Remove :include_blank => #expense.human_state_name
Replace with <%= f.collection_select :state, #expense.state_transitions, :event, :human_to_name, { selected: #expense.human_state_name}, class: "form-control" %>
Update 2
Since state_machine gives you the ability to track & fire instance methods after a successful transition, you may wish to do the following:
#app/models/expense.rb
Class Expense < ActiveRecord::Base
state_machine :state, :initial => :pending do
state :pending
state :approved
state :rejected
event :approve do
transition [:pending, :rejected] => :approved
end
event :reject do
transition [:pending, :approved] => :rejected
end
after_transition :on => :approved, :do => :send_approval_email
after_transition :on => :rejected, :do => :send_rejection_email
def send_approval_email
ExpenseMailer.expense_approved(self).deliver #-> might need to call outide of state_machine block
end
def send_rejection_email
ExpenseMailer.expense_declined(self).deliver
end
end
end
This will give you the ability to perform the following:
#app/controllers/expenses_controller.rb
Class ExpensesController < ApplicationController
def update
#expense = Expense.find params[:id]
if #expense.update(expense_params)
flash[:notice] = "Expense Report Updated"
redirect_to expenses_path
end
end
end
By the way, you need to change your "events" to have different names to your "states". As per my object-oriented references above, you need to be able to call the likes of #object.approve etc