Rails 7.0.4- form_for - collection_select 在编辑操作中有多个选项

Question

我有三个表：

• 职员
• 工作人员_地点
• 地点

商业案例：员工可以在多个地点工作。 Staff 和 Location 之间的关联是通过 staff_locations 表完成的。 在创建员工条目时，我正在选择他/她所属的位置。 这工作正常。

但是我在编辑操作中正确显示 collection_select 时遇到问题。 它显示的次数与 staff_locations 表中与 staff_id 匹配的条目的数量一样多。

我不知道如何解决这个问题，到目前为止我没有在任何地方找到任何好的提示。

楷模

class Staff < ApplicationRecord
has_many :visits, dependent: :destroy
has_many :work_schedules
has_many :customers, through: :visits

    has_many :staff_locations, dependent: :destroy
    has_many :locations, through: :staff_locations
    
    accepts_nested_attributes_for :staff_locations, allow_destroy: true

def staff_locations_attributes=(staff_locations_attributes)

        staff_locations_attributes.values[0][:location_id].each do |loc_id| 
            if !loc_id.blank?
                staff_location_attribute_hash = {}; 
                staff_location_attribute_hash['location_id'] = loc_id;              
                            
                staff_location = StaffLocation.create(staff_location_attribute_hash)
                self.staff_locations << staff_location
            end
            
        end
    end

end

class StaffLocation < ApplicationRecord
belongs_to :staff
belongs_to :location

validates :staff_id, :location_id, uniqueness: true
end

class Location < ApplicationRecord
has_many :staff_locations
has_many :staffs, through: :staff_locations
end

员工控制器

class StaffsController < ApplicationController
before_action :set_staff, only: %i [ show edit update destroy ]

def index
@staffs = Staff.all
end

def show
end

def new
@staff = Staff.new
@staff.staff_locations.build
end

def create
@staff = Staff.new(staff_params)

    if @staff.save
      redirect_to @staff
    else
      render :new, status: :unprocessable_entity
    end

end

def edit
end

def update
respond_to do |format|
if @staff.update(staff_params)
format.html { redirect_to @staff, notice: 'Staff was successfully updated.' }
format.json { render :show, status: :ok, staff: @staff }
else
format.html { render :edit }
format.json { render json: @staff.errors, status: :unprocessable_entity }
end
end
end

def destroy
end

private
    def staff_params
      params.require(:staff).permit(:first_name, :last_name, :status, :staff_type, staff_locations_attributes: [:location_id => [] ])
      #due to multiple select in the new staff form, staff_locations_attributes needs to contain Array of location_ids.
      #Moreover check Staff model's method: staff_locations_attributes. It converts staff_locations_attributes into hashes.
    end

    def set_staff
      @staff = Staff.find(params[:id])
    end

end

形式偏

<%= form_for(@staff) do |form| %>

    <div>
        <% if params["action"] != "edit" %>
            
            <%= form.fields_for :staff_locations do |staff_location_form| %>
                <%= staff_location_form.label :location_id, 'Associated Locations' %><br>
                <%= staff_location_form.collection_select :location_id, Location.all, :id, :loc_name, {include_blank: false}, {:multiple => true } %>
            <% end %>
    
        <% else %>
    
            <%= form.fields_for :staff_locations do |staff_location_form| %>
                <%= staff_location_form.label :location_id, 'Associated Locations' %><br>
                <%= staff_location_form.collection_select :location_id, Location.all, :id, :loc_name, {selected: @staff.locations.map(&:id).compact, include_blank: false}, {:multiple => true} %>
                <% #debugger %>
            <% end %>
    
        <% end %>
    </div>
    
    <div>
        <%= form.submit %>
    </div>

<% end %>

更新

在@Beartech 建议的更改之后，更新方法工作正常。 然而，新的行动停止了。 下面我粘贴了我在提交表单时捕获的内容，以在 Staff 表中创建一个条目并在 Staff_locations 表中创建两个相关条目。

在将 objetct 保存到数据库之前，我在控制台中进行了检查：

• @职员
• @staff.location_ids
• staff_params

之后我确实保存了。 我不明白为什么它以 FALSE 状态结束。

   14|     #@staff.staff_locations.build
    15|   end
    16| 
    17|   def create
    18|     @staff = Staff.new(staff_params)
=>  19|     debugger
    20| 
    21|     respond_to do |format|
    22|       if @staff.save
    23|         format.html { redirect_to @staff, notice: 'Staff was successfully created.' }
=>#0    StaffsController#create at ~/rails_projects/dentysta/app/controllers/staffs_controller.rb:19
  #1    ActionController::BasicImplicitRender#send_action(method="create", args=[]) at ~/rails_projects/dentysta/vendor/bundle/ruby/3.0.0/gems/actionpack-7.0.4/lib/action_controller/metal/basic_implicit_render.rb:6
  # and 75 frames (use `bt' command for all frames)

(ruby) @staff
#<Staff:0x00007f2400acb2e8 id: nil, first_name: "s", last_name: "dd", status: "Active", staff_type: "Doctor", created_at: nil, updated_at: nil>

(ruby) @staff.location_ids
[4, 5]

(ruby) staff_params
#<ActionController::Parameters {"first_name"=>"s", "last_name"=>"dd", "status"=>"Active", "staff_type"=>"Doctor", "location_ids"=>["", "4", "5"]} permitted: true>

(ruby) @staff.save
  TRANSACTION (0.1ms)  begin transaction
  ↳ (rdbg)//home/mw/rails_projects/dentysta/app/controllers/staffs_controller.rb:1:in `create'
  StaffLocation Exists? (0.1ms)  SELECT 1 AS one FROM "staff_locations" WHERE "staff_locations"."staff_id" IS NULL LIMIT ?  [["LIMIT", 1]]
  ↳ (rdbg)//home/mw/rails_projects/dentysta/app/controllers/staffs_controller.rb:1:in `create'
  StaffLocation Exists? (0.1ms)  SELECT 1 AS one FROM "staff_locations" WHERE "staff_locations"."location_id" = ? LIMIT ?  [["location_id", 4], ["LIMIT", 1]]
  ↳ (rdbg)//home/mw/rails_projects/dentysta/app/controllers/staffs_controller.rb:1:in `create'
  CACHE StaffLocation Exists? (0.0ms)  SELECT 1 AS one FROM "staff_locations" WHERE "staff_locations"."staff_id" IS NULL LIMIT ?  [["LIMIT", 1]]
  ↳ (rdbg)//home/mw/rails_projects/dentysta/app/controllers/staffs_controller.rb:1:in `create'
  StaffLocation Exists? (0.3ms)  SELECT 1 AS one FROM "staff_locations" WHERE "staff_locations"."location_id" = ? LIMIT ?  [["location_id", 5], ["LIMIT", 1]]
  ↳ (rdbg)//home/mw/rails_projects/dentysta/app/controllers/staffs_controller.rb:1:in `create'
  TRANSACTION (0.1ms)  rollback transaction
  ↳ (rdbg)//home/mw/rails_projects/dentysta/app/controllers/staffs_controller.rb:1:in `create'
false

(rdbg) c    # continue command

  TRANSACTION (0.1ms)  begin transaction
  ↳ app/controllers/staffs_controller.rb:22:in `block in create'
  StaffLocation Exists? (0.2ms)  SELECT 1 AS one FROM "staff_locations" WHERE "staff_locations"."staff_id" IS NULL LIMIT ?  [["LIMIT", 1]]
  ↳ app/controllers/staffs_controller.rb:22:in `block in create'
  StaffLocation Exists? (0.1ms)  SELECT 1 AS one FROM "staff_locations" WHERE "staff_locations"."location_id" = ? LIMIT ?  [["location_id", 4], ["LIMIT", 1]]
  ↳ app/controllers/staffs_controller.rb:22:in `block in create'
  CACHE StaffLocation Exists? (0.0ms)  SELECT 1 AS one FROM "staff_locations" WHERE "staff_locations"."staff_id" IS NULL LIMIT ?  [["LIMIT", 1]]
  ↳ app/controllers/staffs_controller.rb:22:in `block in create'
  StaffLocation Exists? (0.2ms)  SELECT 1 AS one FROM "staff_locations" WHERE "staff_locations"."location_id" = ? LIMIT ?  [["location_id", 5], ["LIMIT", 1]]
  ↳ app/controllers/staffs_controller.rb:22:in `block in create'
  TRANSACTION (0.1ms)  rollback transaction
  ↳ app/controllers/staffs_controller.rb:22:in `block in create'
  Rendering layout layouts/application.html.erb
  Rendering staffs/new.html.erb within layouts/application
  Location Count (0.1ms)  SELECT COUNT(*) FROM "locations"
  ↳ app/views/staffs/_form.html.erb:36
  Location Load (0.1ms)  SELECT "locations".* FROM "locations"
  ↳ app/views/staffs/_form.html.erb:36
  Rendered staffs/_form.html.erb (Duration: 18.5ms | Allocations: 2989)
  Rendered staffs/new.html.erb within layouts/application (Duration: 21.7ms | Allocations: 3059)
  Rendered layout layouts/application.html.erb (Duration: 24.6ms | Allocations: 4054)
Completed 422 Unprocessable Entity in 2302301ms (Views: 30.1ms | ActiveRecord: 1.8ms | Allocations: 174939)

Answer 1

编辑重要提示：使用多选可能会出现意想不到的用户界面问题。 当您使用下面的代码时，现有记录的多选将加载现有关联位置突出显示为选择。 如果您不触摸该表单元素然后保存表单，它们将保持关联。 但是整个多选列表可能不会立即显示。 如果此人看不到所有选定的元素，他们可以单击一个元素，这将取消选择所有其他元素，从而在记录保存时删除这些关联。 我编辑了答案以添加size:到 HTML 属性。 这将显示所有选项，以便他们可以看到选择了哪些选项以及单击一个选项时会发生什么（取消选择所有其他选项需要 shfit/option select 才能重新选择）。 我会考虑这是否是您正在做的事情的正确界面元素。 您可能希望将collection_check_boxes视为正确的 UI 元素，因为它们必须有目的地取消选择任何想要删除的内容，并且不必在每次添加或删除一个位置时都重新选择它们。

我花了一段时间才记住如何做到这一点。 这是因为您专注于连接表。 通常这就是您想要多个表单域时会做的事情。 但您实际上是在寻求利用has_many关系。

请记住，您的accepts_nested_attributes_for为您提供了一种location_ids=方法，它允许您仅通过传递 ID 来设置这些位置。 Rails 将负责使用连接 model 建立关联。

在您的控制台中尝试：

@staff = Staff.first
# returns a staff object
@staff.locations
#returns an array of location objects due to the has_many
@staff.location_ids
# [12, 32]
@staff.location_ids = [12, 44, 35]
#this will update the joined locations to those locations by id. If any current locations are not in that array, they get deleted from the join table.

改变你的强参数：

  params.require(:staff).permit(:first_name, :last_name, :status,
  :staff_type, staff_locations_attributes: [:location_id => [] ])

到：

  params.require(:staff).permit(:first_name, :last_name, :status,
 :staff_type, :location_ids => [] )

在您的表单中，您只需要一个表单元素，使用@staff上的方法构建：

<%= f.label :locations %><br />
<%= f.collection_select :location_ids, Location.all, :id, :name,{selected: @staff.location_ids, 
include_blank: false}, {:multiple => true, size: Location.all.count } %>

所以这是可行的，因为.location_ids是@staff上的有效方法， Location.all返回所有位置的集合，然后这两个符号（：id 和：name）都是单个位置 object 的有效方法。然后在selected...您只是使用相同的.location_ids来抓取已经存在的那些以将它们标记为已选中。

我忘了怎么做，已经有一段时间了。 一旦我记得它是那么容易。

Answer 2

对于那些将来会遇到类似情况的人，我现在正在粘贴对我有用的东西。 @Beartech 再次感谢您的帮助。 它为我节省了很多时间。

楷模

class Staff < ApplicationRecord
    has_many :visits, dependent: :destroy
    has_many :work_schedules
    has_many :customers, through: :visits

    has_many :staff_locations, dependent: :destroy
    has_many :locations, through: :staff_locations

    accepts_nested_attributes_for :staff_locations, allow_destroy: true
end

class StaffLocation < ApplicationRecord
  belongs_to :staff
  belongs_to :location
end

class Location < ApplicationRecord
    has_many :staff_locations
    has_many :staffs, through: :staff_locations
end

员工控制器

class StaffsController < ApplicationController
  before_action :set_staff, only: %i[ show edit update destroy ]

  def index
    @staffs = Staff.all
  end

  def show
    #debugger
  end

  def new
    @staff = Staff.new
  end

  def create
    @staff = Staff.new(staff_params)
    debugger

    respond_to do |format|
      if @staff.save!
        format.html { redirect_to @staff, notice: 'Staff was successfully created.' }
        format.json { render :show, status: :ok, staff: @staff }
        #redirect_to @staff
      else
        format.html { render :new, status: :unprocessable_entity, notice: 'Somthing went wrong' }
        format.json { render json: @staff.errors, status: :unprocessable_entity }
        #render :new, status: :unprocessable_entity
      end
    end
  end

  def edit
  end

  def update
    respond_to do |format|
      if @staff.update(staff_params)
        format.html { redirect_to @staff, notice: 'Staff was successfully updated.' }
        format.json { render :show, status: :ok, staff: @staff }
      else
        format.html { render :edit }
        format.json { render json: @staff.errors, status: :unprocessable_entity }
      end
    end
  end

  def destroy
  end

  private
    def staff_params
      params.require(:staff).permit(:first_name, :last_name, :status, :staff_type, :location_ids => [] )    
    end

    def set_staff
      @staff = Staff.find(params[:id])
    end

end

_form部分

<%= form_for(@staff) do |form| %>
    <div>
        <%= form.label :first_name %><br>
        <%= form.text_field :first_name %>
        <% @staff.errors.full_messages_for(:first_name).each do |message| %>
            <div><%= message %></div>
        <% end %>
    </div>

    <div>
        <%= form.label :last_name %><br>
        <%= form.text_field :last_name %>
        <% @staff.errors.full_messages_for(:last_name).each do |message| %>
            <div><%= message %></div>
        <% end %>
    </div>

    <div>
        <%= form.label :staff_type %><br>
        <%= form.collection_select :staff_type, Staff.valid_types, :to_s, :to_s, {include_blank: false}, {:multiple => false} %>
        <% @staff.errors.full_messages_for(:staff_type).each do |message| %>
            <div><%= message %></div>
        <% end %>
    </div>

    <div>
        <%= form.label :status %><br>
        <%= form.collection_select :status, Staff.valid_statuses, :to_s, :to_s, {include_blank: false}, {:multiple => false} %>
        <% @staff.errors.full_messages_for(:status).each do |message| %>
            <div><%= message %></div>
        <% end %>
    </div>

    <div>
        <%= form.label :locations %><br />
        <%= form.collection_select :location_ids, Location.all, :id, :loc_name,{selected: @staff.location_ids, include_blank: false}, {:multiple => true, size: Location.all.count } %>
    </div>

    <div>
        <%= form.submit %>
    </div>

<% end %>