没有路由匹配导致ActionController UrlGenerationError

Question

我根据Hartl的教程创建了一个ToDoList，并按照video和worded tutorial添加了标记系统。我一直遵循到第10节，他们要求我将new.html.erb文件修改为源代码中所示的代码。为了临时解决代码的结构差异，我将编辑一些其他文件，例如本例中的micropost_form partial。有时，我在视频代码和措辞教程中的代码之间进行了交替，因为其中一些会产生错误消息或无法产生所需的功能。这是我认为与该问题有关的文件。

_micropost_form.html.erb（将在用户主页上显示的填写表格）

<%= simple_form_for @micropost do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="field">
    <%= f.label :content %><br />
    <%= f.text_area :content, placeholder: "Add new task..." %>
  </div>
  <div class="field">
    <%= f.label :tag_list, "Tags (separated by commas)" %><br />
    <%= f.text_field :tag_list %> 
  </div>
  <%= f.submit "Add Task", class: "btn btn-primary" %>
<% end %>

micropost.html.erb（用于显示单个微博）

<li id="micropost-<%= micropost.id %>">
  <%= link_to gravatar_for(micropost.user, size: 50), micropost.user %>
  <span class="user"><%= link_to micropost.user.name, user_path(micropost.user) %></span>
  <span class="content"><%= micropost.content %></span>
  <p><small>Tags: <%= raw micropost.tags.map(&:name).map { |t| link_to t, tag_path(t) }.join(', ') %></small</p>
  <span class="timestamp">
    Posted <%= time_ago_in_words(micropost.created_at) %> ago.
    <% if current_user?(micropost.user) %>
      <%= link_to "Done", micropost_path(micropost), method: :delete, data: { confirm: "Keep up the good work!" } %>
    <% end %>
  </span>
</li>

routes.rb

Rails.application.routes.draw do
  resources :users
  resources :microposts          

  get    '/about',   to: 'static_pages#about'
  get    '/contact', to: 'static_pages#contact'
  get    '/signup',  to: 'users#new'
  post    '/signup',  to: 'users#create'
  get    '/login',    to: 'sessions#new'
  post   '/login',    to: 'sessions#create'
  delete '/logout',   to: 'sessions#destroy'
  get   '/users/admin',     to: 'users#admin'

  get 'tags/:tag', to: 'microposts#index', as: :tag

  root   'static_pages#home'
end

micropost_controller

class MicropostsController < ApplicationController
  before_action :logged_in_user, only: [:create, :destroy]
  before_action :correct_user,   only: :destroy


  def index
    params[:tag] ? @microposts = Micropost.tagged_with(params[:tag]) : @microposts = Micropost.all
  end


  def show
    @micropost = Micropost.find(params[:id])
  end

  def create
    @micropost = current_user.microposts.build(micropost_params)
    if @micropost.save
      flash[:success] = "Micropost created!"
      redirect_to root_url
    else
      @feed_items = []
      render 'static_pages/home'
    end
  end

  def destroy
    @micropost.destroy
    flash[:success] = "You have deleted a task!"
    redirect_to request.referrer || root_url
  end

  private

    def micropost_params
      params.require(:micropost).permit(:content, :tag_list, :tag, 
        {tag_ids: [] }, :tag_ids)
    end

    def correct_user
      @micropost = current_user.microposts.find_by(id: params[:id])
      redirect_to root_url if @micropost.nil?
    end
end

Micropost模型

class Micropost < ApplicationRecord
  belongs_to :user
  has_many :taggings
  has_many :tags, through: :taggings
  default_scope -> { order(created_at: :desc) }
  validates :user_id, presence: true
  validates :content, presence: true, length: {maximum: 140 }
  attr_accessor :tag_list



  def self.tagged_with(name)
    Tag.find_by!(name: name).microposts
  end

  def self.tag_counts
    Tag.select('tags.*, count(taggings.tag_id) as count')
    .joins(:taggings).group('taggings.tag_id')
  end

  def tag_list
    tags.map(&:name).join(', ')
  end

  def tag_list=(names)
    self.tags = names.split(',').map do |n|
      Tag.where(name: n.strip).first_or_create!
    end
  end
end

标记模型

class Tag < ApplicationRecord
    attr_accessor :name
  has_many :taggings
  has_many :microposts, through: :taggings
end

static_pages控制器

class StaticPagesController < ApplicationController
  def home
    if logged_in?
      @micropost  = current_user.microposts.build
      @feed_items = current_user.feed.paginate(page: params[:page])
    end
  end

  def help
  end

  def about
  end

  def contact
  end
end

feed.html.erb

<% if @feed_items.any? %>
  <ol class="microposts">
    <%= render @feed_items %>
  </ol>
  <%= will_paginate @feed_items %>
<% end %>

我遇到以下错误

ActionController::UrlGenerationError in StaticPages#home
No route matches {:action=>"index", :controller=>"microposts", :tag=>nil}, missing required keys: [:tag]

app/views/microposts/_micropost.html.erb:5:in `block in _app_views_microposts__micropost_html_erb___3891111682689684005_70324923859580'
app/views/microposts/_micropost.html.erb:5:in `map'
app/views/microposts/_micropost.html.erb:5:in `_app_views_microposts__micropost_html_erb___3891111682689684005_70324923859580'
app/views/shared/_feed.html.erb:3:in `_app_views_shared__feed_html_erb__3168328449514417483_70324923896060'
app/views/static_pages/home.html.erb:13:in `_app_views_static_pages_home_html_erb__3511776991923566869_70324898321240'

有人可以在这里提出什么问题吗？请让我知道是否需要更多信息。

更新：我已经实现了以下答案提供的一些更改，但仍然不明白为什么未检测到:tag，以及为什么红色代码实际上被突出显示了。

Answer 1

ActionController::UrlGenerationError in StaticPages#home
No route matches {:action=>"index", :controller=>"microposts", :tag=>nil}, missing required keys: [:tag]

问题是您的微博没有索引路径。

Rails.application.routes.draw do
  root   'static_pages#home'
  get    '/readme',    to: 'static_pages#readme'
  get    '/about',   to: 'static_pages#about'
  get    '/contact', to: 'static_pages#contact'
  get    '/signup',  to: 'users#new'
  post    '/signup',  to: 'users#create'
  get    '/login',    to: 'sessions#new'
  post   '/login',    to: 'sessions#create'
  delete '/logout',   to: 'sessions#destroy'
  get   '/users/admin',     to: 'users#admin'
  resources :users
  resources :microposts,          only: [:create, :destroy] #Here's the problem
  get 'tags/:tag', to: 'microposts#index', as: :tag
end

更改为：

resources :microposts, only: [:index, :create, :destroy]

编辑：

另一个问题是

if logged_in?
  @micropost  = current_user.microposts.build #this just returns a new 1
  @feed_items = current_user.feed.paginate(page: params[:page])
end

您可能想要类似的东西：

if logged_in?
  @microposts  = current_user.microposts
  @feed_items = Micropost.all.paginate(page: params[:page])
end

这将为您提供所有用户的微博。然后，您可以在视图中遍历它们。

Answer 2

我实际上发现问题的原因很简单。运行rails console后，似乎我的db：seed甚至没有正确倾斜，导致我的标签具有nil的名称，并导致我找不到路由。深入研究Rails console is adding nil instead of values以解决我的种子添加问题，我意识到我已经添加了attr_accessor，忘记了应该通过命令行将常规属性添加到Migration中，而不是直接写入Model中。根据帖子删除它会更新我的数据库，并且代码可以正常工作。