nested_forms_presentation.md

Easy Nested Forms with Rails

Introduction

• What are nested forms?
  • Forms that allow you to save information not only for a base element, but for related elements of the main element

Basic Form

• Someone is asking for a SalesOrder Form in which the client name can be set (as plain text)
• What is required to accomplish that?

  • SalesOrder model

      class SalesOrder < ActiveRecord::Base
        # Allows to set a name
      end

  • View for displaying the form

      = form_for :sales_order do |sof|
        = sof.label_field :name
        = sof.text_field :name
        = sof.submit

  • SalesOrder info processing in the controller

      class SalesOrdersController
        def create
          sales_order = params[:sales_order]
          sales_order.save
        end
      end

Nested Form

• Suddenly, that someone is asking for allowing to save a Product for a Salesorder
• What is required to accomplish it?

  • Models

    • Product model

        class Product < ActiveRecord::Base
          belongs_to :sales_order
        end
      

    • SalesOrder model

        class SalesOrder < ActiveRecord::Base
          has_many :products
          accepts_nested_attributes_for :products
        end
      

  • View for displaying the form

      = form_for :sales_order do |sof|
        - #other content
        = sof.fields_for :product do |pf|
          = pf. :name
          = pf.text_field :name
        = sof.submit

  • SalesOrder info processing in the controller

      class SalesOrdersController
        def create
          sales_order = params[:sales_order]
          sales_order.save
        end
      end

    • The same than in the previous example!

Can Rails handle complex forms?

• Complex Nested Forms can be accomplished:
  • For instance, to have a SalesOrder Form having a Product having ProductVariant
  • Nested Forms addition in Real Time
    • As many as needed
    • You can take advantage of the "unobstrusive javascript" feature from Rails
      • You add the fewer JS required, which makes even easier to maintain the forms

Conclusion

• As we seen, Rails Nested Forms are very practical, easy to setup, and to maintain
• Also, Rails handles the params by you, so you don't have to worry about that
• A very viable option for implementing Nested Forms when working on a Rails App