Rails：并非所有关联的用户帖子都出现在列表中

Question

目前共有三种型号：users、teachers和posts。

我能够建立关联，以便教师可以看到他们的用户的帖子，这些关联（感谢迄今为止大家的帮助）：

class Teacher < ActiveRecord::Base
  has_many :users
  has_many :posts, through: :users
def user_posts
    Post.where(id: users.map(&:id))
  end
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable
end

另外，用户：belongs_to :teacher, has_many :posts 发帖：belongs_to :user

目标是让教师看到他们用户的帖子。但是，它只是部分起作用 - 错误是 当老师查看他的用户的帖子时，只显示少数帖子。

例如，用户 Corey 发布了 2 个帖子。但是他的老师菲尼先生只能看到其中的一条。我已尝试重置数据库并创建新条目，但问题仍然存在。有谁知道为什么会这样以及任何潜在的解决方案？

教师控制器

class TeachersController < ApplicationController
  before_action :find_teacher, only: [:index]

def index
 @posts = @findteacher.user_posts
 @teachers = Teacher.all
end

def show
  @teacher = Teacher.find_by_username(params[:id])
end

private
  def find_teacher
    @findteacher = current_teacher
  end
end

用户控制器

class UsersController < ApplicationController

def self.find_for_authentication(conditions)
  conditions = ["username = ? or email = ?", conditions[authentication_keys.first], conditions[authentication_keys.first]]
  # raise StandardError, conditions.inspect
  super
end

def index
    @users = User.all
end

def show
  @user = User.find_by_username(params[:id])
end
end

 def destroy
    @user.destroy
    respond_to do |format|
      format.html { redirect_to :back, notice: 'User was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

帖子控制器

class PostsController < ApplicationController

  before_action :set_post, only: [:show, :edit, :update, :destroy]

  # GET /posts
  # GET /posts.json

def index
  if params[:user_id]
    @posts = Post.where(user_id: params[:user_id])
  else
    @posts = Post.all
  end
end

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

  # GET /posts/new
  def new
    @post = current_user.posts.build

  end

  # GET /posts/1/edit
  def edit
  end

  # POST /posts
  # POST /posts.json
  def create
    @post = current_user.posts.build(post_params)

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

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

  # DELETE /posts/1
  # DELETE /posts/1.json
  def destroy
    @post.destroy
    respond_to do |format|
      format.html { redirect_to :back, notice: 'Post was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

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

    # Never trust parameters from the scary internet, only allow the white list through.
    def post_params
      params.require(:post).permit(:user_id, :username, :Duration, :Rating)
    end
end

教师索引.html.erb

<p id="notice"><%= notice %></p>

<h1><%= current_teacher.username %>  student posts</h1>

Studio Posts for <%= current_teacher.username %> (Your id: <%= current_teacher.id %>)

<p>
<table>
  <thead>
    <tr>
       <th>UserID</th>
      <th>User</th>
      <th>Created At</th>
      <th>Duration</th>
      <th>Rating</th>
      <th>TeacherID</th>

      <th colspan="3"></th>

    </tr>
  </thead>

  <tbody>
    <% @posts.each do |post| %>

      <tr>
        <td><%= post.user_id %></td>
        <td><%= link_to post.user.username, post.user %></td>

        <td><%= post.created_at %></td>
        <td><%= post.Duration %></td>
        <td><%= post.Rating %></td>
        <td><%= post.user.teacher_id %></td>
        <td><%= link_to 'Show', post %></td>
        <td><%= link_to 'Edit', edit_post_path(post) %></td>
        <td><%= link_to 'Destroy', post, method: :delete, data: { confirm: 'Are you sure?' } %></td>
      </tr>
    <% end %>
  </tbody>

</table>

架构（只是其中的一部分）

create_table "users", force: :cascade do |t|
    t.string   "email",                  default: "", null: false
    t.string   "encrypted_password",     default: "", null: false
    t.string   "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          default: 0,  null: false
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.inet     "current_sign_in_ip"
    t.inet     "last_sign_in_ip"
    t.datetime "created_at",                          null: false
    t.datetime "updated_at",                          null: false
    t.string   "username"
    t.integer  "teacher_id"
end

...

  create_table "posts", force: :cascade do |t|
    t.integer  "user_id"
    t.integer  "Duration"
    t.text     "Rating"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.text     "username"
...
  create_table "users", force: :cascade do |t|
    t.string   "email",                  default: "", null: false
    t.string   "encrypted_password",     default: "", null: false
    t.string   "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          default: 0,  null: false
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.inet     "current_sign_in_ip"
    t.inet     "last_sign_in_ip"
    t.datetime "created_at",                          null: false
    t.datetime "updated_at",                          null: false
    t.string   "username"
    t.integer  "teacher_id"
  end

Answer 1

问题出在Teacher类的这个方法中

def user_posts
  Post.where(id: users.map(&:id))
end

查询应该是Post.where(user_id: users.map(&:id)

可能 Corey 有一个 id=1，他发布了 2 个帖子，一个是 id=1，一个是 id=2，但两者都有 user_id=1。您的原始查询执行此Post.where(id: [1])，导致仅显示一篇帖子。但正确的查询应该是Post.where(user_id: [1])，它返回用户的所有帖子。