How to create form for many to many association in Rails 4.2

Question

I'm trying to create Recipes app. In my app I have table Ingredients (name), table Recipes (type_of, code, description) join table Quantities (recipe_id, ingredient_id, quantity)

I would like to be able to add Ingredients to my Recipe while creating. Recipe can have many ingredients.

My models:

class Ingredient < ActiveRecord::Base
   has_many :quantities
   has_many :recipes, through: :quantities
   has_many :stock_of_ingredients
end

class Quantity < ActiveRecord::Base
  belongs_to :recipe
  belongs_to :ingredient

  accepts_nested_attributes_for :ingredient,
                                :reject_if => :all_blank
end

class Recipe < ActiveRecord::Base
   has_many :quantities
   has_many :ingredients, :through => :quantities
    accepts_nested_attributes_for :quantities,
           :reject_if => :all_blank,
           :allow_destroy => true
  accepts_nested_attributes_for :ingredients

end   

My Recipe controller was created from scaffolding so is

def create
    @recipe = Recipe.new(recipe_params)

    respond_to do |format|
      if @recipe.save
        format.html { redirect_to @recipe, notice: 'Recipe was successfully created.' }
        format.json { render :show, status: :created, location: @recipe }
      else
        format.html { render :new }
        format.json { render json: @recipe.errors, status: :unprocessable_entity }
      end
    end   end

I have also added

  def recipe_params
      params.require(:recipe).permit(:type_of_base, :code, :description, :quantities_attributes =>[:quantity, :recipe_id, :ingredient_id, :ingredient_attributes])
    end

I didn't know that I need quantity controller can that be created from base controller?

Now my form looks like this

<%= form_for(@recipe, html: { class: "form-horizontal", role: "form" }) do |f| %>
 ...

  <div class="form-group">
   ...
  </div>
<div class="ingderdient-wraper">
  <%= render "quantites/quantity_fields" %>
</div>


  <div class="form-group">
    <div class="col-sm-offset-2 col-sm-10">
      <%= f.submit class: "btn btn-primary" %>
    </div>
  </div>
<% end %>

And my rendered file

 <%= text_field :quantity %>
  <%= select :ingredient_ids, Ingredient.all.collect {|x| [x.name, x.id]}, {}, :multiple => true %>

But that not working properly also I would like to have a possibility to add more ingredient that one. Need a button ADD MORE.

If someone could explain to me how to get to the point. Regards

Answer 1

From what I understood you just need to make a javascript methods to dynamically generate the fields, you could follw this rails cast http://railscasts.com/episodes/197-nested-model-form-part-2. This is exactly what you need.

Answer 2

In my opinion, You have problem with Model. In this task You should use the has_and_belongs_to_many (habtm) association. You could see Active Record Associations

You could make Model:

class Ingredient < ActiveRecord::Base
   has_and_belongs_to_many :recipes
...
end

class Recipe < ActiveRecord::Base
   has_and_belongs_to_many :ingredients
...
end 

In migrations:

def self.up
    create_table :ingradients, force: true do |t|
      t.string :name    
      t.references :recipe, index: true
      t.timestamps null: false    
    end
    create_table :recipes, force: true do |t|
      t.string :name    
      t.references :ingradient, index: true
      t.timestamps null: false    
    end
    create_table :ingradients_recipes, force: true, id: false do |t|
      t.belongs_to :ingradient, index: true
      t.belongs_to :recipe, index: true
      t.integer    :quantity
    end
  end

I think the next steps will be simple...