Nested Attributes Duplication

[Emmanuel Mathews]

I have a duplication problem when using the accepts nested attributes method. I have an app thats an ecommerce app, when I create a new product and add a nested attribute everything works fine. But if I hit edit product and then update changes it creates a duplicate of the nested attributes I had on there before, and it keeps doing it each time I update, even when no changes are made. Is there something Im missing? or is it related to rails 4

This is my model, controller for the following

Product Model

class Product < ActiveRecord::Base

has_many :variants

accepts_nested_attributes_for :variants

end

Variant Model

class Variant < ActiveRecord::Base

belongs_to :product

end

Product Controller

def new

    @product = Product.new

    3.times { @product.variants.build }

end

def update

    respond_to do |format|

      if @product.update(product_params)

        format.html { redirect_to @product, notice: 'Product was successfully updated.' }

        format.json { head :no_content }

      else

        format.html { render action: 'edit' }

        format.json { render json: @product.errors, status: :unprocessable_entity }

      end

    end

  end

  private

    # Use callbacks to share common setup or constraints between actions.

    def set_product

      @product = Product.find(params[:id])

    end

    # Never trust parameters from the scary internet, only allow the white list through.

    def product_params

      params.require(:product).permit(:name, :description, :brand_id, :category_id, :subcategory_id, :slug, variants_attributes: [:sku, :color, :size, :price, :stock, :slug ] )

    end

end