How to update a model record? [Rails 4] - ruby-on-rails

Question

I need to update my Pack model in my Rails application, but every time I submit the form, nothing happens. Here's the code:
packs_controller.rb
def edit
#pack = Pack.find(params[:id])
end
def update
#pack = Pack.find(params[:id])
if #pack.update_attributes(pack_params)
flash[:success] = "Update successful!"
redirect_to '/packs'
else
render 'edit'
end
end
private
def pack_params
params.require(:pack).permit(:amount)
end
_edit_packs.html.haml
= form_for(#pack) do |f|
.form-group
= f.label :amount
= f.text_field :amount, :autofocus => true, class: 'form-control'
= f.submit 'Submit', :class => 'button right'
Any ideas?
EDIT
Here is the log when pressing submit:
Started PATCH "/packs/11" for 127.0.0.1 at 2014-06-13 19:27:12 +0200
Started PATCH "/packs/11" for 127.0.0.1 at 2014-06-13 19:27:12 +0200
Processing by PacksController#update as HTML
Processing by PacksController#update as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"oa20eUeZPxbV+mX0mQyDyFibwWCnOlrtP/9uoKq2HU0=", "pack"=>{"amount"=>"1"}, "commit"=>"Submit", "id"=>"11"}
Parameters: {"utf8"=>"✓", "authenticity_token"=>"oa20eUeZPxbV+mX0mQyDyFibwWCnOlrtP/9uoKq2HU0=", "pack"=>{"amount"=>"1"}, "commit"=>"Submit", "id"=>"11"}
Pack Load (0.1ms) SELECT "packs".* FROM "packs" WHERE "packs"."id" = ? ORDER BY created_on DESC LIMIT 1 [["id", 11]]
Pack Load (0.1ms) SELECT "packs".* FROM "packs" WHERE "packs"."id" = ? ORDER BY created_on DESC LIMIT 1 [["id", 11]]
(0.1ms) begin transaction
(0.1ms) begin transaction
Pack Exists (0.1ms) SELECT 1 AS one FROM "packs" WHERE ("packs"."created_on" = '2014-06-13' AND "packs"."id" != 11) LIMIT 1
Pack Exists (0.1ms) SELECT 1 AS one FROM "packs" WHERE ("packs"."created_on" = '2014-06-13' AND "packs"."id" != 11) LIMIT 1
(0.0ms) rollback transaction
(0.0ms) rollback transaction
Rendered packs/_edit_packs.html.haml (1.8ms)
Rendered packs/_edit_packs.html.haml (1.8ms)
Rendered packs/edit.html.haml within layouts/application (2.5ms)
Rendered packs/edit.html.haml within layouts/application (2.5ms)
User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 3 ORDER BY "users"."id" ASC LIMIT 1
User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = 3 ORDER BY "users"."id" ASC LIMIT 1
Rendered layouts/_navigation_links.html.erb (1.2ms)
Rendered layouts/_navigation_links.html.erb (1.2ms)
Rendered layouts/_navigation.html.haml (1.9ms)
Rendered layouts/_navigation.html.haml (1.9ms)
Rendered layouts/_messages.html.haml (0.1ms)
Rendered layouts/_messages.html.haml (0.1ms)
Completed 200 OK in 28ms (Views: 22.0ms | ActiveRecord: 0.6ms)
Completed 200 OK in 28ms (Views: 22.0ms | ActiveRecord: 0.6ms)
EDIT 2
After having looked through some of the comments, and thinking about the problem, it seems like there's a problem with my uniqueness validation on the :created_on field, which stores the date the record was created on.
EDIT 3
Confirmed: :created_on is the root of the problem! I have a validation that enforces the uniqueness of :created_on. When I remove it, the form works. Here is my model:
pack.rb
class Pack < ActiveRecord::Base
belongs_to :user
default_scope -> { order('created_on DESC') }
scope :today, -> { where(:created_at => (Time.now.beginning_of_day..Time.now)) }
scope :week, -> { where(:created_at => (Time.now.beginning_of_week..Time.now))}
scope :month, -> { where(:created_at => (Time.now.beginning_of_month..Time.now))}
scope :year, -> { where(:created_at => (Time.now.beginning_of_year..Time.now))}
validates :user_id, presence: true
validates :created_on, uniqueness: true
validates :amount, presence: true, length: { maximum: 1 }
end
Any suggestions on how to get around this? Should I start a new question?

Answer 1

Based on your logs, it looks like you have multiple packs in your database that were created_on is equal to '2014-06-13' which will cause the created_on uniqueness validation to fail.
Check this in the rails console:
Pack.where(created_on: '2014-06-13')
If there is more than one, delete the extras and it should work.

Answer 2

If you are trying to limit a pack to one per user per day you need to add a scope option to the created on validation:
validates :created_on, uniqueness: true, scope: user