Presenter的未定义局部变量或方法`params'

Question

我有一个索引视图，它变得有点笨重，所以我将所有数据库查询移动到演示器中以尝试清理内容。

但是，在任何查询中使用 params[:something] 都会使演示者出错：

undefined local variable or method params for QuestionPresenter:0x007fd6d569c158

我曾尝试将参数移动到 applicationcontroller 和模型中的辅助方法中，但没有成功。

我怎样才能让演示者可以使用这些参数？或者演示者不打算处理这些参数？

旧的 question_controller.rb

def index       
   if params[:tag]
      @questions = @question.tagged_with(params[:tag]).paginate(page: params[:page], per_page: 20)
    elsif params[:search]
      @questions = @question.paginate(page: params[:page], per_page: 20).search(params[:search])
    else
      @newest = @questions.newest.paginate(page: params[:page], per_page: 2)
      @unanswered = @question.unanswered.paginate(page: params[:page], per_page: 2).search(params[:search])
      @votes = @question.by_votes.paginate(page: params[:page], per_page: 2).search(params[:search])
  end 
end

QuestionsController.rb（新索引操作）

def index
  @presenter = QuestionPresenter.new
end

question_presenter.rb

class QuestionPresenter
  def initialize
    @questions = Question
    @tags = Tag
  end

  def questions
    @questions.paginate(page: params[:page], per_page: 20).search(params[:search])
  end

  def tags
   @tags.joins(:taggings).select('tags.*, count(tag_id) as "tag_count"').group(:tag_id).order(' tag_count desc')
  end

  def tagged_questions
    @questions.tagged_with(params[:tag])
  end

  def newest
    @questions.newest.paginate(page: params[:page], per_page: 20)
  end

  def unanswered
    @questions.unanswered.paginate(page: params[:page], per_page: 20)
  end

  def votes
    @questions.by_votes.paginate(page: params[:page], per_page: 20)
  end
end

index.html.erb

<%= render partial: "questions/tag_cloud", locals: {tags: @presenter.tags} %>

<% if params[:search] %> 
  <%= render partial: "questions/questions", locals: {questions: @presenter.questions} %>
<% elsif params[:tag] %>
  <%= render partial: "questions/questions", locals: {questions: @presenter.tagged_questions}%>
<% else %>
  <%= render partial: "questions/tabbed_index", locals: {questions: @presenter.newest, unanswered: @presenter.unanswered, votes: @presenter.votes} %>
<% end %>

Answer 1

您必须将 params 哈希值从控制器传递给您的 QuestionPresenter：

QuestionsController.rb（新索引操作）

def index
  @presenter = QuestionPresenter.new(params)
end

question_presenter.rb

class QuestionPresenter
  def initialize(params = {})
    @questions = Question
    @tags = Tag
    @params = params
  end

  def params
    @params
  end

  ...

end