CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-5rails-activerecord
jean182
jean182

Reputation: 3515

How to implement Update and destroy methods with a has many through association? Rails 5

Hi I'm having trouble by making the update and destroy method in my posts_controller, I'm able to create new Posts but I'm not able to update and I want to know how to destroy the model while destroying all the associations with the other model it.

My models: Post Model

class Post < ApplicationRecord
 has_many :comments, dependent: :destroy
 has_many :has_categories
 has_many :categories, through: :has_categories

 validates :title, presence: true,
 length: { minimum: 5 }
 after_create :save_categories

 def categories=(value)
  @categories = value
 end

 private

 def save_categories
   @categories.each do |category_id|
    HasCategory.create(category_id: category_id, post_id: self.id)
   end
 end
end

Has_Category model

class HasCategory < ApplicationRecord
  belongs_to :post
  belongs_to :category
end

Category Model

class Category < ApplicationRecord
  validates :name, presence: true
  has_many :has_categories
  has_many :posts, through: :has_categories
end

So in my partial form for the new and the edit actions is like this

<%= form_with model: @post, local: true do |form| %>
  <!--Inputs before the categories-->
  <div>
    <label>Categories</label>
    <% @categories.each do |category| %>
      <div>
        <%= check_box_tag "categories[]", category.id %> <%= category.name %>
      </div>
    <% end %>
 </div>
 <div>
  <%= form.submit %>
 </div>
<% end %>

My posts_controller create and update method

def create
  @post = Post.new(post_params)
  @post.categories = params[:categories]
  if @post.save
    redirect_to @post
  else
    render :new
  end
end

def update
  @post = Post.find(params[:id])
  @post.categories = params[:categories]
  if @post.update(post_params)
    redirect_to @post
  else
    render :edit
  end
end

My create action is working but the update action is just updating the inputs before the check_box_tag. I know that the save_categories method on my Post model is the one who is taking the array I'm receiving from the form and creating the HasCategory association, How should I make the update action or even the destroy action given the situation that Is a many to many association?

Upvotes: 0

Views: 528

Answers (1)

Vasilisa
Vasilisa

Reputation: 4640

The line has_many :categories, through: :has_categories gives you category_ids for post. So you can change your form:

<%= form_with model: @post, local: true do |form| %>
  <!--Inputs before the categories-->
  <div>
    <label>Categories</label>
    <%= f.collection_check_boxes(:category_ids, @categories, :id, :name) 
  </div>
  <div>
   <%= form.submit %>
  </div>
<% end %>

and controller:

def create
  # you need it here for correct rerendering `new` on validation error
  @categories = Category.all # or maybe you have here more complicated query
  @post = Post.new(post_params)      
  if @post.save
    redirect_to @post
  else
    render :new
  end
end

def update
  # you need it here for correct rerendering `edit` on validation error
  @categories = Category.all # or maybe you have here more complicated query        
  @post = Post.find(params[:id])
  if @post.update(post_params)
    redirect_to @post
  else
    render :edit
  end
end

private

def post_params
  params.require(:post).permit(:name, :some_other_post_params, category_ids: [])
end

You need to remove callback and categories=(value) method from the Post model. And define @categories in the new and edit actions. If it equals Category.all you can just put it to the form: f.collection_check_boxes(:category_ids, Category.all, :id, :name), without defining @variable

Upvotes: 0

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