Ruby on rails 按班级对学生进行分类

我有一个学生模型，其中包含名称：string和教室：string列

我希望有一个页面列出每个班级的学生

i、 e.
本地主机：3000/学生/1E1
本地主机：3000/学生/1E2
本地主机：3000/学生/1E3
等

我似乎无法解决问题。这是我第一次尝试自己开发Rails应用程序。但我真的被卡住了！希望有人能帮我

此代码在我的学生\u controller.rb中

class StudentsController < ApplicationController
  def index
    @students = Student.all
  end

  def show
    @student = Student.find(params[:id])
  end


  def sort_by_class
    @student = Student.find(params[:id])
    @class = @student.classroom
  end

end

<h1>Students#show</h1>
<p>Find me in app/views/students/show.html.erb</p>


<%= @student.name %>
<%= @student.classroom%>

class Student < ActiveRecord::Base

  has_and_belongs_to_many :classrooms

end

class Classroom < ActiveRecord::Base

  has_and_belongs_to_many :students

end

class Student < ActiveRecord::Base

  belongs_to :classroom

end

class Classroom < ActiveRecord::Base

  has_many :students

end

class ClassroomsController < ApplicationController
  def index
    @classrooms = Classroom.all
  end

  def show
    @classroom = Classroom.find(params[:id])
  end
end

<h1><%= @classroom.number %></h1>

<table>
  <thead>
  <tr>
    <th> Name </th>
  </tr>
  </thead>
  <tbody>
    <% @classroom.students.each do |student| %>
      <tr>
        <td><%= student.name %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<h1>Classrooms</h1>
<table>
  <% @classrooms.each do |classroom| %>
    <tr>
      <td><%= classroom %></td>
      <td><%= link_to(classroom, classroom_path(classroom)) %></td>
    </tr>
  <% end %>
</table>

<h1>Classroom <%= @classroom %> Students</h1>
<table>
  <% @students.each do |student| %>
    <tr>
      <td><%= student.name %></td>
    </tr>
  <% end %>
</table>

class StudentsController

此代码位于my show.html.erb

class StudentsController < ApplicationController
  def index
    @students = Student.all
  end

  def show
    @student = Student.find(params[:id])
  end


  def sort_by_class
    @student = Student.find(params[:id])
    @class = @student.classroom
  end

end

<h1>Students#show</h1>
<p>Find me in app/views/students/show.html.erb</p>


<%= @student.name %>
<%= @student.classroom%>

class Student < ActiveRecord::Base

  has_and_belongs_to_many :classrooms

end

class Classroom < ActiveRecord::Base

  has_and_belongs_to_many :students

end

class Student < ActiveRecord::Base

  belongs_to :classroom

end

class Classroom < ActiveRecord::Base

  has_many :students

end

class ClassroomsController < ApplicationController
  def index
    @classrooms = Classroom.all
  end

  def show
    @classroom = Classroom.find(params[:id])
  end
end

<h1><%= @classroom.number %></h1>

<table>
  <thead>
  <tr>
    <th> Name </th>
  </tr>
  </thead>
  <tbody>
    <% @classroom.students.each do |student| %>
      <tr>
        <td><%= student.name %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<h1>Classrooms</h1>
<table>
  <% @classrooms.each do |classroom| %>
    <tr>
      <td><%= classroom %></td>
      <td><%= link_to(classroom, classroom_path(classroom)) %></td>
    </tr>
  <% end %>
</table>

<h1>Classroom <%= @classroom %> Students</h1>
<table>
  <% @students.each do |student| %>
    <tr>
      <td><%= student.name %></td>
    </tr>
  <% end %>
</table>

学生秀
在app/views/students/show.html.erb中查找我

按类排序是另一种路径，还是要在索引中按类排序

假设教室是与学生的关联（属于：教室），并且在学生表中有一个教室id列，您可以执行类似于student.order（：教室id）

的操作，最好将“教室”作为模型并与学生关联：

m-n学生和教室协会： 在终端中生成：

rails g model classroom number:string
rails g migration create_classrooms_student classroom:references student:references

rails g model classroom number:string
rails g migration add_classroom_id_to_students classroom:references

模型/student.rb

class StudentsController < ApplicationController
  def index
    @students = Student.all
  end

  def show
    @student = Student.find(params[:id])
  end


  def sort_by_class
    @student = Student.find(params[:id])
    @class = @student.classroom
  end

end

<h1>Students#show</h1>
<p>Find me in app/views/students/show.html.erb</p>


<%= @student.name %>
<%= @student.classroom%>

class Student < ActiveRecord::Base

  has_and_belongs_to_many :classrooms

end

class Classroom < ActiveRecord::Base

  has_and_belongs_to_many :students

end

class Student < ActiveRecord::Base

  belongs_to :classroom

end

class Classroom < ActiveRecord::Base

  has_many :students

end

class ClassroomsController < ApplicationController
  def index
    @classrooms = Classroom.all
  end

  def show
    @classroom = Classroom.find(params[:id])
  end
end

<h1><%= @classroom.number %></h1>

<table>
  <thead>
  <tr>
    <th> Name </th>
  </tr>
  </thead>
  <tbody>
    <% @classroom.students.each do |student| %>
      <tr>
        <td><%= student.name %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<h1>Classrooms</h1>
<table>
  <% @classrooms.each do |classroom| %>
    <tr>
      <td><%= classroom %></td>
      <td><%= link_to(classroom, classroom_path(classroom)) %></td>
    </tr>
  <% end %>
</table>

<h1>Classroom <%= @classroom %> Students</h1>
<table>
  <% @students.each do |student| %>
    <tr>
      <td><%= student.name %></td>
    </tr>
  <% end %>
</table>

模型/student.rb

class StudentsController < ApplicationController
  def index
    @students = Student.all
  end

  def show
    @student = Student.find(params[:id])
  end


  def sort_by_class
    @student = Student.find(params[:id])
    @class = @student.classroom
  end

end

<h1>Students#show</h1>
<p>Find me in app/views/students/show.html.erb</p>


<%= @student.name %>
<%= @student.classroom%>

class Student < ActiveRecord::Base

  has_and_belongs_to_many :classrooms

end

class Classroom < ActiveRecord::Base

  has_and_belongs_to_many :students

end

class Student < ActiveRecord::Base

  belongs_to :classroom

end

class Classroom < ActiveRecord::Base

  has_many :students

end

class ClassroomsController < ApplicationController
  def index
    @classrooms = Classroom.all
  end

  def show
    @classroom = Classroom.find(params[:id])
  end
end

<h1><%= @classroom.number %></h1>

<table>
  <thead>
  <tr>
    <th> Name </th>
  </tr>
  </thead>
  <tbody>
    <% @classroom.students.each do |student| %>
      <tr>
        <td><%= student.name %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<h1>Classrooms</h1>
<table>
  <% @classrooms.each do |classroom| %>
    <tr>
      <td><%= classroom %></td>
      <td><%= link_to(classroom, classroom_path(classroom)) %></td>
    </tr>
  <% end %>
</table>

<h1>Classroom <%= @classroom %> Students</h1>
<table>
  <% @students.each do |student| %>
    <tr>
      <td><%= student.name %></td>
    </tr>
  <% end %>
</table>

或者简单的方法：

为教室创建新控制器

class ClassroomsController < ApplicationController
  def index
    @classrooms = Student.group(:classroom).pluck(:classroom)
  end

  def show
    @classroom = params[:id]
    @students = Student.where(params[:id])
  end
end

class ClassroomsController

index.html.erb

class StudentsController < ApplicationController
  def index
    @students = Student.all
  end

  def show
    @student = Student.find(params[:id])
  end


  def sort_by_class
    @student = Student.find(params[:id])
    @class = @student.classroom
  end

end

<h1>Students#show</h1>
<p>Find me in app/views/students/show.html.erb</p>


<%= @student.name %>
<%= @student.classroom%>

class Student < ActiveRecord::Base

  has_and_belongs_to_many :classrooms

end

class Classroom < ActiveRecord::Base

  has_and_belongs_to_many :students

end

class Student < ActiveRecord::Base

  belongs_to :classroom

end

class Classroom < ActiveRecord::Base

  has_many :students

end

class ClassroomsController < ApplicationController
  def index
    @classrooms = Classroom.all
  end

  def show
    @classroom = Classroom.find(params[:id])
  end
end

<h1><%= @classroom.number %></h1>

<table>
  <thead>
  <tr>
    <th> Name </th>
  </tr>
  </thead>
  <tbody>
    <% @classroom.students.each do |student| %>
      <tr>
        <td><%= student.name %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<h1>Classrooms</h1>
<table>
  <% @classrooms.each do |classroom| %>
    <tr>
      <td><%= classroom %></td>
      <td><%= link_to(classroom, classroom_path(classroom)) %></td>
    </tr>
  <% end %>
</table>

<h1>Classroom <%= @classroom %> Students</h1>
<table>
  <% @students.each do |student| %>
    <tr>
      <td><%= student.name %></td>
    </tr>
  <% end %>
</table>

教室

show.html.erb

class StudentsController < ApplicationController
  def index
    @students = Student.all
  end

  def show
    @student = Student.find(params[:id])
  end


  def sort_by_class
    @student = Student.find(params[:id])
    @class = @student.classroom
  end

end

<h1>Students#show</h1>
<p>Find me in app/views/students/show.html.erb</p>


<%= @student.name %>
<%= @student.classroom%>

class Student < ActiveRecord::Base

  has_and_belongs_to_many :classrooms

end

class Classroom < ActiveRecord::Base

  has_and_belongs_to_many :students

end

class Student < ActiveRecord::Base

  belongs_to :classroom

end

class Classroom < ActiveRecord::Base

  has_many :students

end

class ClassroomsController < ApplicationController
  def index
    @classrooms = Classroom.all
  end

  def show
    @classroom = Classroom.find(params[:id])
  end
end

<h1><%= @classroom.number %></h1>

<table>
  <thead>
  <tr>
    <th> Name </th>
  </tr>
  </thead>
  <tbody>
    <% @classroom.students.each do |student| %>
      <tr>
        <td><%= student.name %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<h1>Classrooms</h1>
<table>
  <% @classrooms.each do |classroom| %>
    <tr>
      <td><%= classroom %></td>
      <td><%= link_to(classroom, classroom_path(classroom)) %></td>
    </tr>
  <% end %>
</table>

<h1>Classroom <%= @classroom %> Students</h1>
<table>
  <% @students.each do |student| %>
    <tr>
      <td><%= student.name %></td>
    </tr>
  <% end %>
</table>

课堂学生

我只想要这样的页面……localhost:3000/students/1E1 localhost:3000/students/1E2 localhost:3000/students/1E3。那么：课堂应该是另一种模式吗？还是应该是学生属性之一？创建关系时使用

：references

。它将自动在该字段上创建索引。谢谢大家。现在我明白了。我不认为课堂作为一种模式是完全有意义的。。。对于像你们这样善良慷慨的人来说，学习是伟大的。再次感谢。：）@Exsemt还删除了

\u id

后缀，因为它现在不需要。