Rails：用于在创建新子记录时选择现有父级的表单？

Question

I have a has_many and belongs_to association set up between two models: Project and Task.

I'd like to be able to create a form which enables me to create a new Task and assign an existing Project as a parent. For example, this form might have a pulldown for selecting from a list of existing projects.

There are only a finite set of projects available in this application, so I've created Project records via a seeds.rb file. I do not need to make a form for creating new Projects.

I believe I've achieved a solution by using a collection_select form helper tag in the new Task form. I'm pretty happy with how this works now, but just curious if there are other approaches to this problem.

#models/project.rb
class Project < ActiveRecord::Base
  has_many :tasks, :dependent => :destroy
end

#models/task.rb
class Task < ActiveRecord::Base
  belongs_to :project
end

#controllers/tasks_controller.rb
class TasksController < ApplicationController

  def new
    @task = Task.new

    respond_to do |format|
      format.html # new.html.erb
      format.xml  { render :xml => @task }
    end
  end

  def create
    @task = Task.new(params[:task])

    respond_to do |format|
      if @task.save
        format.html { redirect_to(@task, :notice => 'Task was successfully created.') }
        format.xml  { render :xml => @task, :status => :created, :location => @task }
      else
        format.html { render :action => "new" }
        format.xml  { render :xml => @task.errors, :status => :unprocessable_entity }
      end
    end
  end
end

#views/new.html.erb
<h1>New task</h1>

<%= form_for(@task) do |f| %>
  <div class="field">
    <%= f.label :name %><br />
    <%= f.text_field :name %>
  </div>
  <div class="select">
    <%= collection_select(:task, :project_id, Project.all, :id, :name) %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

<%= link_to 'Back', tasks_path %>

Answer 1

I just reviewed your code and this looks fantastic to me. One small tweak:

<%= f.collection_select(:project_id, Project.all, :id, :name) %>

This is just slightly cleaner in that you're still using the |f| block variable

Answer 2

Since you mentioned other approaches, I would definitely mention and actually recommend, you use formtastic . The associations are handled automatically and keeps your code clean and also gives you some great customization options.