Question

我以前遇到类似这个问题，但这次我无法解决它，我在这里做了很多搜索和谷歌，但我找不到我面临的相同情况

我有3个模特，学生，科目，参加，每次我尝试通过参加表格将学生分配给多个科目时，subject_id保存为null以防使用check_boxes ，我尝试使用f.association :subject，但它给出了相同的结果，数组"attend"=>{"student_id"=>"1", "subject_id"=>["1", "2", ""]}}中也有一个空值，这是我的代码

student.rb

class Student < ActiveRecord::Base
  attr_accessible :first_name, :middle_name, :last_name, :gender, :user_id
  belongs_to :user
  has_many :attends
  has_many :subjects, :through => :attends

  def full_name
    "#{self.first_name} #{self.last_name}"
  end
end

subject.rb中

class Subject < ActiveRecord::Base
  attr_accessible :subject_title, :subjectCode
  has_many :attends
  has_many :students, :through => :attends
end

attend.rb

class Attend < ActiveRecord::Base
  attr_accessible :student_id, :subject_id
  belongs_to :student
  belongs_to :subject
end

出席/ new.html.erb

<%= simple_form_for(@attend) do |f| %>
              <%= f.association :student, as: :select, label_method: :full_name, prompt: 'Select Student' %>
              <%= f.input :subject_id, collection:@subjects, as: :check_boxes,label_method: :subject_title, value_method: :id %>
              <% end %>

attends_controller.rb

class AttendsController < ApplicationController
  def index
    @attends = Attend.all
  end

  def show
    @attend = Attend.find(params[:id])

  end

  def new
    @attend = Attend.new
    @subjects = Subject.all
  end

  def create
    @attend = Attend.new(params[:attend])
    if @attend.save
      redirect_to attends_path
    else
      render 'new'
    end
  end

  def edit
    @attend = Attend.find(params[:id])
  end

  def update
    @attend = Attend.find(params[:id])
    if @attend.update_attributes(params[:attend])
      redirect_to attends_path
    else
      render 'edit'
    end
  end

  def destroy
    @attend = Attend.find(params[:id])
  end
end

服务器开发日志

  Parameters: {"utf8"=>"✓", "authenticity_token"=>"8Z9LTJbYpNnFtvLKs4MpO2pongrKmFkSIz0jzxcuQH0=", "attend"=>{"student_id"=>"1", "subject_id"=>["1", "2", ""]}}
  User Load (0.2ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
   (0.1ms)  begin transaction
  SQL (0.4ms)  INSERT INTO "attends" ("created_at", "student_id", "subject_id", "updated_at") VALUES (?, ?, ?, ?)  [["created_at", Sat, 14 Dec 2013 11:34:02 UTC +00:00], ["student_id", 1], ["subject_id", nil], ["updated_at", Sat, 14 Dec 2013 11:34:02 UTC +00:00]]
   (169.6ms)  commit transaction

Answer 1

您正试图以简单的形式保存中间关系。在您的控制器创建方法中，@ attend仅用于保存一条记录。但是你想在那里输入很多科目。问题只出在那里。

简单形式：has_many通过复选框nil值

1 个答案: