I'm trying to solve a pretty common (as I thought) task.
There're three models:
class Product < ActiveRecord::Base
validates :name, presence: true
has_many :categorizations
has_many :categories, :through => :categorizations
accepts_nested_attributes_for :categorizations
end
class Categorization < ActiveRecord::Base
belongs_to :product
belongs_to :category
validates :description, presence: true # note the additional field here
end
class Category < ActiveRecord::Base
validates :name, presence: true
end
My problems begin when it comes to Product new/edit form.
When creating a product I need to check categories (via checkboxes) which it belongs to. I know it can be done by creating checkboxes with name like 'product[category_ids][]'. But I also need to enter a description for each of checked relations which will be stored in the join model (Categorization).
I saw those beautiful Railscasts on complex forms, habtm checkboxes, etc. I've been searching StackOverflow hardly. But I haven't succeeded.
I found one post which describes almost exactly the same problem as mine. And the last answer makes some sense to me (looks like it is the right way to go). But it's not actually working well (i.e. if validation fails). I want categories to be displayed always in the same order (in new/edit forms; before/after validation) and checkboxes to stay where they were if validation fails, etc.
Any thougts appreciated. I'm new to Rails (switching from CakePHP) so please be patient and write as detailed as possible. Please point me in the right way!
Thank you. : )
Looks like I figured it out! Here's what I got:
My models:
class Product < ActiveRecord::Base
has_many :categorizations, dependent: :destroy
has_many :categories, through: :categorizations
accepts_nested_attributes_for :categorizations, allow_destroy: true
validates :name, presence: true
def initialized_categorizations # this is the key method
[].tap do |o|
Category.all.each do |category|
if c = categorizations.find { |c| c.category_id == category.id }
o << c.tap { |c| c.enable ||= true }
else
o << Categorization.new(category: category)
end
end
end
end
end
class Category < ActiveRecord::Base
has_many :categorizations, dependent: :destroy
has_many :products, through: :categorizations
validates :name, presence: true
end
class Categorization < ActiveRecord::Base
belongs_to :product
belongs_to :category
validates :description, presence: true
attr_accessor :enable # nice little thingy here
end
The form:
<%= form_for(@product) do |f| %>
...
<div class="field">
<%= f.label :name %><br />
<%= f.text_field :name %>
</div>
<%= f.fields_for :categorizations, @product.initialized_categorizations do |builder| %>
<% category = builder.object.category %>
<%= builder.hidden_field :category_id %>
<div class="field">
<%= builder.label :enable, category.name %>
<%= builder.check_box :enable %>
</div>
<div class="field">
<%= builder.label :description %><br />
<%= builder.text_field :description %>
</div>
<% end %>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
And the controller:
class ProductsController < ApplicationController
# use `before_action` instead of `before_filter` if you are using rails 5+ and above, because `before_filter` has been deprecated/removed in those versions of rails.
before_filter :process_categorizations_attrs, only: [:create, :update]
def process_categorizations_attrs
params[:product][:categorizations_attributes].values.each do |cat_attr|
cat_attr[:_destroy] = true if cat_attr[:enable] != '1'
end
end
...
# all the rest is a standard scaffolded code
end
From the first glance it works just fine. I hope it won't break somehow.. :)
Thanks all. Special thanks to Sandip Ransing for participating in the discussion. I hope it will be useful for somebody like me.
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