Form object pattern in Rails

#rails

🤔 Motivation

In the case of ..,

The form in the view isn't made from only one model
You don't want to write the form specific logic in the model

You might want to introduce a form object. Because it isolates the responsibility from model/view/controller to form.

👍 Solution

1. Introduce a form class

# forms/dog_form.rb
class DogForm
  include ActiveModel::Model

  attr_accessor  :id, :name

  validates :name, presence: true

  # This method is for getting dog collection with some 制約 
  def search
    rel = Operation
    rel = rel.where(id: id) if id.present?
    rel = rel.where("name LIKE (?)", "%#{name}%") if name.present?
    rel = rel.newer
  end

  def save
    return false if invalid?
    # do something ( save, notify, logging)
    true
  end
end

2. Use it in any controller

# dogs_controller.rb
def index
  @serach_form = DogForm.new(params[:search])
  @dogs = @serach_form.search.page params[:page]
end

3. The erb will be like this

# dogs/index.html.erb
<%= form_for(@serach_form, as: 'search', url: manage_dogs_path, html:{method: :get}) do |f| %>
  <div>
    <div><%= f.text_field :id %></div>
    <div><%= f.text_field :name %></div>
  </div>
  <%= f.button t('words.actions.search') %>
<% end %>