我正在尝试在我的应用程序中设置多个标记。我使用了一个单独的标记和标记模型，它可以很好地标记单个模型。
然而，在建立关联后，当我想创建一个实际指向<%= select_tag(:kategory_id, options_for_select(@kategories), :prompt => "Select Category", class: "form-control") %>的新问题undefined method map for nil:NilClass时，我遇到了这个错误。我不知道它为什么指向这个，因为它和标签无关。我可能在某个地方犯了一个我无法理解的错误。
以下是我的设置方法。
我将taggable_id和taggable_type添加到标签表中。
class AddAttributesToTaggings < ActiveRecord::Migration[5.1]
def change
add_column :taggings, :taggable_id, :integer
add_column :taggings, :taggable_type, :string
add_index :taggings, [:taggable_type, :taggable_id]
end
end
Tag.rb
class Tag < ApplicationRecord
has_many :taggings
has_many :posts, through: :taggings, source: :taggable, source_type: Post
has_many :questions, through: :taggings, source: :taggable, source_type: Question
has_many :user_tags, dependent: :destroy
has_many :users, through: :user_tags
extend FriendlyId
friendly_id :name, use: :slugged
def should_generate_new_friendly_id?
name_changed?
end
end
标记.rb
class Tagging < ApplicationRecord
belongs_to :tag
belongs_to :taggable, :polymorphic => true
end
问题.rb
class Question < ApplicationRecord
belongs_to :user
belongs_to :kategory
validates :title, :content, presence: true
is_impressionable counter_cache: true, unique: :all
Question.order('impressions_count DESC')
scope :most_recent, -> { order(created_at: :desc) }
extend FriendlyId
friendly_id :title, use: :slugged
def should_generate_new_friendly_id?
title_changed?
end
include Taggable
def related_questions
Question.joins(:tags).where(tags: { id: self.tags.pluck(:id) }).where.not(id: self.id)
end
end
模型/关注点/taggable.rb
module Taggable
extend ActiveSupport::Concern
included do
has_many :taggings, :as => :taggable
has_many :tags, :through => :taggings
end
def tag_list
self.tags.collect do |tag|
tag.name
end.join(", ")
end
def tag_list=(tags_string)
tag_names = tags_string.split(",").collect{|s| s.strip.downcase}.uniq
new_or_found_tags = tag_names.collect { |name| Tag.friendly.find_or_create_by(name: name) }
self.tags = new_or_found_tags
end
end
schema.rb 中的标签和标记表
create_table "taggings", force: :cascade do |t|
t.bigint "tag_id"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "taggable_id"
t.string "taggable_type"
t.index ["tag_id"], name: "index_taggings_on_tag_id"
t.index ["taggable_type", "taggable_id"], name: "index_taggings_on_taggable_type_and_taggable_id"
end
create_table "tags", force: :cascade do |t|
t.string "name"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "slug"
t.index ["slug"], name: "index_tags_on_slug", unique: true
end
问题/\uform
<%= form_with(model: question, local: true) do |form| %>
<% if question.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(question.errors.count, "error") %> prohibited this question from being saved:</h2>
<ul>
<% question.errors.full_messages.each do |message| %>
<li><%= message %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<b><%= form.label "Category" %></b>
<%= select_tag(:kategory_id, options_for_select(@kategories), :prompt => "Select Category", class: "form-control") %>
</div>
<br>
<div class="field">
<b><%= form.label :title %></b>
<%= form.text_field :title, id: :question_title, class: "form-control" %>
</div>
<br>
<div class="field">
<%= form.label :content %>
<%= form.text_area :content, id: :question_content, class: "form-control" %>
</div>
<br>
<div>
<%= form.label :tag_list %>
<%= form.text_field :tag_list %>
</div>
<br>
<div class="actions">
<%= form.submit %>
</div>
<% end %>
问题_控制器.rb
class QuestionsController < ApplicationController
before_action :set_question, only: [:show, :edit, :update, :destroy]
before_action :authenticate_user!
before_action :find_contacts
before_action :find_kategory
impressionist :actions=>[:show,:index]
# GET /questions
# GET /questions.json
def index
if params[:kategory].blank?
@questions = Question.most_recent
else
@kategory_id = Kategory.find_by(name: params[:kategory]).id
@questions = Question.where(:kategory_id => @kategory_id).most_recent
end
end
# GET /questions/1
# GET /questions/1.json
def show
impressionist(@question)
@most_viewed = Question.order('impressions_count DESC').take(20)
end
# GET /questions/new
def new
@question = current_user.questions.build
@kategories = Kategory.all.map{ |k| [k.name, k.id] }
end
# GET /questions/1/edit
def edit
@kategories = Kategory.all.map{ |k| [k.name, k.id] }
end
# POST /questions
# POST /questions.json
def create
@question = current_user.questions.build(question_params)
@question.kategory_id = params[:kategory_id]
respond_to do |format|
if @question.save
flash[:success] = 'Your question was successfully posted.'
format.html { redirect_to @question }
format.json { render :show, status: :created, location: @question }
else
format.html { render :new }
format.json { render json: @question.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /questions/1
# PATCH/PUT /questions/1.json
def update
respond_to do |format|
if @question.update(question_params)
flash[:success] = 'Your question was successfully updated.'
format.html { redirect_to @question }
format.json { render :show, status: :ok, location: @question }
else
format.html { render :edit }
format.json { render json: @question.errors, status: :unprocessable_entity }
end
end
end
# DELETE /questions/1
# DELETE /questions/1.json
def destroy
@question.destroy
respond_to do |format|
flash[:success] = 'Your question has been deleted.'
format.html { redirect_to questions_url }
format.json { head :no_content }
end
end
def most_viewed
@questions = Question.order('impressions_count DESC').take(20)
end
private
# Use callbacks to share common setup or constraints between actions.
def set_question
@question = Question.friendly.includes(:tags).find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def question_params
params.require(:question).permit(:title, :content, :kategory_id, :tag_list)
end
def find_contacts
@contacts = user_signed_in? ? current_user.all_active_contacts : ''
end
def find_kategory
@questions = Kategory.where(:kategory_id => @kategory_id)
end
end
更新：**我现在可以在不添加任何标记的情况下保存问题，但添加了标记后，我得到了一个表单错误tagging is invalid**当我编辑问题时，标签会正确加载
错误日志：
Started POST "/questions" for 127.0.0.1 at 2018-07-13 12:01:01 +0100
Processing by QuestionsController#create as HTML
Parameters: {"utf8"=>"√", "authenticity_token"=>"hgLn8bzd6fVSzCIPtRd3P0Jp/LEso
/h5cKNBY0a80x3i4RF6tpLlRyqmls3xRFryqyP1/s/rLDVIt9C1/uK+qw==", "kategory_id"=>"1"
, "question"=>{"title"=>"Help!!! My Dell Inspiron 6400 is hanging", "content"=>"
Lorem ipsum dolor amet seitan offal ethical, beard viral lo-fi put a bird on it
salvia actually yr. Ethical ennui pitchfork fanny pack, gentrify seitan sartoria
l bespoke. Viral 90's church-key swag, you probably haven't heard of them banh m
i intelligentsia brunch DIY iceland wolf pitchfork. Everyday carry photo booth n
ormcore XOXO tumblr portland.rnrnBrooklyn heirloom kombucha, edison bulb leg
gings hell of DIY chartreuse austin tacos bitters. Blog hexagon copper mug blue
bottle cray. Post-ironic direct trade kale chips mumblecore. Craft beer squid cr
onut vape, hoodie bitters succulents ramps snackwave vegan small batch brunch ch
ia food truck umami. Chillwave blue bottle viral raclette authentic health goth
vape coloring book cardigan 3 wolf moon taxidermy. Gluten-free tote bag hella, l
omo pinterest direct trade gastropub tattooed. Iceland hammock post-ironic, bush
wick cornhole tumeric dreamcatcher blog palo santo chartreuse 90's food truck sy
nth chicharrones.", "tag_list"=>"hardware"}, "commit"=>"Create Question"}
User Load (2.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 ORDE
R BY "users"."id" ASC LIMIT $2 [["id", 3], ["LIMIT", 1]]
Private::Conversation Load (2.9ms) SELECT "private_conversations".* FROM "pri
vate_conversations" WHERE ("private_conversations"."recipient_id" = $1 OR "priva
te_conversations"."sender_id" = $2) [["recipient_id", 3], ["sender_id", 3]]
Private::Message Load (2.0ms) SELECT "private_messages".* FROM "private_messa
ges" WHERE "private_messages"."conversation_id" IN (2, 3, 4, 6)
Group::Conversation Load (3.9ms) SELECT "group_conversations".* FROM "group_c
onversations" INNER JOIN "group_conversations_users" ON "group_conversations"."i
d" = "group_conversations_users"."conversation_id" WHERE "group_conversations_us
ers"."user_id" = $1 [["user_id", 3]]
Group::Message Load (2.0ms) SELECT "group_messages".* FROM "group_messages" W
HERE "group_messages"."conversation_id" = 1
User Load (2.0ms) SELECT "users".* FROM "users" WHERE "users"."id" IN (2, 3,
5)
(40.0ms) SELECT "group_conversations"."id" FROM "group_conversations" INNER
JOIN "group_conversations_users" ON "group_conversations"."id" = "group_conversa
tions_users"."conversation_id" WHERE "group_conversations_users"."user_id" = $1
[["user_id", 3]]
CACHE (0.0ms) SELECT "group_conversations"."id" FROM "group_conversations" I
NNER JOIN "group_conversations_users" ON "group_conversations"."id" = "group_con
versations_users"."conversation_id" WHERE "group_conversations_users"."user_id"
= $1 [["user_id", 3]]
User Load (2.9ms) SELECT "users".* FROM "users" INNER JOIN "contacts" ON "use
rs"."id" = "contacts"."contact_id" WHERE "contacts"."user_id" = $1 AND "contacts
"."accepted" = $2 [["user_id", 3], ["accepted", "t"]]
User Load (4.9ms) SELECT "users".* FROM "users" INNER JOIN "contacts" ON "use
rs"."id" = "contacts"."user_id" WHERE "contacts"."contact_id" = $1 AND "contacts
"."accepted" = $2 ORDER BY "users"."created_at" ASC [["contact_id", 3], ["accep
ted", "t"]]
Tag Load (2.0ms) SELECT "tags".* FROM "tags" WHERE "tags"."name" = $1 LIMIT
$2 [["name", "hardware"], ["LIMIT", 1]]
Kategory Load (10.7ms) SELECT "kategories".* FROM "kategories"
(1.0ms) BEGIN
Question Exists (4.9ms) SELECT 1 AS one FROM "questions" WHERE ("questions".
"id" IS NOT NULL) AND "questions"."slug" = $1 LIMIT $2 [["slug", "help-my-dell-
inspiron-6400-is-hanging"], ["LIMIT", 1]]
Kategory Load (5.9ms) SELECT "kategories".* FROM "kategories" WHERE "kategor
ies"."id" = $1 LIMIT $2 [["id", 1], ["LIMIT", 1]]
(0.0ms) ROLLBACK
Rendering questions/new.html.erb within layouts/application
Rendered questions/_form.html.erb (17.6ms)
Rendered questions/new.html.erb within layouts/application (141.6ms)
Rendered layouts/navigation/header/_toggle_button.html.erb (1.0ms)
Rendered layouts/navigation/header/_home_button.html.erb (30.3ms)
User Load (28.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIM
IT $2 [["id", 5], ["LIMIT", 1]]
Rendered layouts/navigation/header/dropdowns/conversations/_private.html.erb (
73.2ms)
User Load (2.9ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMI
T $2 [["id", 3], ["LIMIT", 1]]
CACHE User Load (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = $
1 LIMIT $2 [["id", 5], ["LIMIT", 1]]
Rendered layouts/navigation/header/dropdowns/conversations/_private.html.erb (
109.4ms)
Rendered layouts/navigation/header/dropdowns/conversations/_group.html.erb (3.
9ms)
User Load (30.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIM
IT $2 [["id", 1], ["LIMIT", 1]]
Rendered layouts/navigation/header/dropdowns/conversations/_private.html.erb (
40.0ms)
CACHE User Load (0.0ms) SELECT "users".* FROM "users" WHERE "users"."id" = $
1 LIMIT $2 [["id", 3], ["LIMIT", 1]]
User Load (2.9ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMI
T $2 [["id", 2], ["LIMIT", 1]]
Rendered layouts/navigation/header/dropdowns/conversations/_private.html.erb (
100.6ms)
Rendered layouts/navigation/header/dropdowns/_conversations.html.erb (983.4ms)
User Load (2.0ms) SELECT "users".* FROM "users" INNER JOIN "contacts" ON "use
rs"."id" = "contacts"."user_id" WHERE "contacts"."contact_id" = $1 AND "contacts
"."accepted" = $2 [["contact_id", 3], ["accepted", "f"]]
Rendered layouts/navigation/header/dropdowns/contact_requests/_no_requests.htm
l.erb (1.0ms)
Rendered layouts/navigation/header/dropdowns/_contact_requests.html.erb (374.0
ms)
Rendered layouts/navigation/header/_dropdowns.html.erb (1713.9ms)
Rendered layouts/navigation/_header.html.erb (2485.4ms)
Kategory Load (2.9ms) SELECT "kategories".* FROM "kategories"
Rendered layouts/navigation/collapsible_elements/_constant_links.html.erb (2.0
ms)
(2.0ms) SELECT COUNT(*) FROM "questions" INNER JOIN "save_questions" ON "que
stions"."id" = "save_questions"."question_id" WHERE "save_questions"."user_id" =
$1 [["user_id", 3]]
Rendered layouts/navigation/collapsible_elements/_signed_in_links.html.erb (21
.5ms)
Rendered layouts/navigation/_collapsible_elements.html.erb (543.0ms)
Rendered layouts/_navigation.html.erb (3323.2ms)
Rendered layouts/application/_private_conversations_windows.html.erb (1.0ms)
Rendered layouts/application/_group_conversations_windows.html.erb (2.0ms)
Completed 200 OK in 22203ms (Views: 21796.6ms | ActiveRecord: 158.2ms)
您需要在创建和更新操作中定义@kategories = Kategory.all.map{ |k| [k.name, k.id] }。如果无法保存问题，则此操作会重新提交新的/编辑操作，并且需要@kategories来重新提交
如果你提供完整的服务器日志来创建操作，我可以尝试帮助你弄清楚-为什么@question不能保存
在我看来，您的@kategories或其中的某个东西(可能是name(为零，因此出现错误：((希望这是一件好事，因为您的标记可能一切都很好。(
确保new操作中的Kategory.all.map { |k| [k.name, k.id] }正在返回记录，并且此错误应该会消失。
注意：您也可以在此处使用options_from_collection_for_select。
# in the controller
def new
@question = current_user.questions.build
@kategories = Kategory.all
end
# and the view
<%= select_tag(:kategory_id, options_from_collection_for_select(@kategories, :name, :id), prompt: "Select Category", class: "form-control") %>
这样，如果你没有任何类别，你就不会出现错误——相反，你就没有任何可用的选项。