Nested form in Ruby on Rails 1.0

Examples

• 0

  How to setup a nested form in Ruby on Rails
  0

  The first to thing to have: a model that contains a has_many relation with another model.

  class Project < ApplicationRecord
    has_many :todos
  end
  
  class Todo < ApplicationRecord
    belongs_to :project
  end
  

  In ProjectsController:

  class ProjectsController < ApplicationController
    def new
      @project = Project.new
    end
  end
  

  In a nested form, you can create child objects with a parent object at the same time.

  <%= nested_form_for @project do |f| %>
    <%= f.label :name %>
    <%= f.text_field :name %>
  
    <% # Now comes the part for `Todo` object %>
    <%= f.fields_for :todo do |todo_field| %>
      <%= todo_field.label :name %>
      <%= todo_field.text_field :name %>
    <% end %>
  <% end %>
  

  As we initialized @project with Project.new to have something for creating a new Project object, same way for creating a Todo object, we have to have something like this, and there are multiple ways to do so:

  1. In Projectscontroller, in new method, you can write: @todo = @project.todos.build or @todo = @project.todos.new to instantiate a new Todo object.

  2. You can also do this in view: <%= f.fields_for :todos, @project.todos.build %>

  For strong params, you can include them in the following way:

  def project_params
    params.require(:project).permit(:name, todo_attributes: [:name])
  end
  

  Since, the Todo objects will be created through the creation of a Project object, so you have to specify this thing in Project model by adding the following line:

  accepts_nested_attributes_for :todos
  

  created Dec 13 '16 at 17:46

  
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