Question

我有属于提交的学生，我需要一个下拉菜单，向学生展示，以便用户可以选择其中一个。我尝试使用它，但它不起作用：

<%= collection_select(:student_name, :submission_id, Submission.all, :form_id, :title) %>

submission.rb：

class Submission < ActiveRecord::Base
  belongs_to :form
  has_one :student
end

student.rb：

class Student < ActiveRecord::Base
  belongs_to :submission
end

submission_controller.rb：

class SubmissionsController < ApplicationController
  before_action :set_submission, only: [:show, :edit, :update, :destroy]
  before_action :set_form

  # GET /submissions/new
  def new
    @submission = Submission.new
  end

  # GET /submissions/1/edit
  def edit
  end

  # POST /submissions
  # POST /submissions.json
  def create
    @submission = Submission.new(submission_params)
    @submission.form_id = @form.id

    respond_to do |format|
      if @submission.save
        format.html { redirect_to @form, notice: 'Submission was successfully created.' }
        format.json { render :show, status: :created, location: @submission }
      else
        format.html { render :new }
        format.json { render json: @submission.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /submissions/1
  # PATCH/PUT /submissions/1.json
  def update
    respond_to do |format|
      if @submission.update(submission_params)
        format.html { redirect_to @submission, notice: 'Submission was successfully updated.' }
        format.json { render :show, status: :ok, location: @submission }
      else
        format.html { render :edit }
        format.json { render json: @submission.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /submissions/1
  # DELETE /submissions/1.json
  def destroy
    @submission.destroy
    respond_to do |format|
      format.html { redirect_to submissions_url, notice: 'Submission was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_submission
      @submission = Submission.find(params[:id])
    end

    def set_form
      @form = Form.find(params[:form_id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def submission_params
      params.require(:submission).permit(:conflict, :computer, :extra_time, :am_pm)
    end
end

student_controller.rb：

class StudentsController < ApplicationController
  before_action :set_student, only: [:show, :edit, :update, :destroy]

  # GET /students
  # GET /students.json
  def index
    @students = Student.all
  end

  # GET /students/1
  # GET /students/1.json
  def show
  end

  # GET /students/new
  def new
    @student = Student.new
  end

  # GET /students/1/edit
  def edit
  end

  # POST /students
  # POST /students.json
  def create
    @student = Student.new(student_params)

    respond_to do |format|
      if @student.save
        format.html { redirect_to @student, notice: 'Student was successfully created.' }
        format.json { render :show, status: :created, location: @student }
      else
        format.html { render :new }
        format.json { render json: @student.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /students/1
  # PATCH/PUT /students/1.json
  def update
    respond_to do |format|
      if @student.update(student_params)
        format.html { redirect_to @student, notice: 'Student was successfully updated.' }
        format.json { render :show, status: :ok, location: @student }
      else
        format.html { render :edit }
        format.json { render json: @student.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /students/1
  # DELETE /students/1.json
  def destroy
    @student.destroy
    respond_to do |format|
      format.html { redirect_to students_url, notice: 'Student was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_student
      @student = Student.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def student_params
      params.require(:student).permit(:student_name)
    end
end

提交表格：

<%= form_for([@form, @submission]) do |f| %>
  <% if @submission.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@submission.errors.count, "error") %> prohibited this submission from being saved:</h2>

      <ul>
        <% @submission.errors.full_messages.each do |message| %>
          <li><%= message %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :conflict %><br />
    <%= f.radio_button :conflict, :Yes, required: :true %> Yes<br>
    <%= f.radio_button :conflict, :No, required: :true %> No
  </div>
  <br>
  <div class="field">
    <%= f.label :computer %><br />
    <%= f.radio_button :computer, :Yes, required: :true %> Yes<br>
    <%= f.radio_button :computer, :No, required: :true %> No
  </div>
  <br>
  <div class="field">
    <%= f.label :am_pm %><br />
    <%= f.radio_button :am_pm, :Am, required: :true %> Am<br>
    <%= f.radio_button :am_pm, :Pm, required: :true %> Pm
  </div>
  <br>
  <div class="field">
    <%= f.label "Student" %><br />
    <%= collection_select(:student_name, :submission_id, Submission.all, :form_id, :title) %>
  </div>
  <br>
  <div class="field">
    <%= f.label :extra_time %><br />
    <%= f.radio_button :extra_time, 25, required: :true %> 25%<br>
    <%= f.radio_button :extra_time, 50, required: :true %> 50%
  </div>
  <br>
  <div class="actions">
    <%= f.submit "Submit", class: "btn btn-primary" %>
  </div>
<% end %>

希望找到答案！感谢

Answer 1

我假设您有一个提交表单，并且您希望学生在其下方下拉。

如果是这种情况，请执行以下操作 -

<%= f.select(:student_id, Student.all.collect { |s| [s.name, s.id] }, {:include_blank => true, :selected => f.object.student_id}) %>

通过执行上述操作，名称将显示在下拉列表中，ID将与选项标记绑定。

有关详细信息，请查看此内容 - http://apidock.com/rails/ActionView/Helpers/FormBuilder/select

Answer 2

我找到了答案：

<%= collection_select(:student, :student_id, Student.all, :id, :student_name, prompt: true) %>

谢谢大家

DropDown与其他模型rails的名称

2 个答案: