Rails -基于类别选择的子类别填充

Question

我试图为一个名为:子类别的属性提供一组输入值，它是基于另一个名为: based的属性的值的。

我有一份表格，上面有：

<div class="nested-fields">
<div class="container-fluid">

  <div class="form-inputs">

    <%= f.input :irrelevant, :as => :boolean, :label =>  "Is an ethics review required or applicable to this project?"  %>

    <%= f.input :category, collection: [ "Risk of harm", "Informed consent", "Anonymity and Confidentiality", "Deceptive practices", "Right to withdraw"], :label => "Principle",  prompt: 'select' %>

    <%= f.input :subcategory,  collection: text_for_subcategory(@ethic.category), :label => "Subcategory", prompt: 'select'  %>


    <%= f.input :considerations, as: :text, :label => "Identify the ethics considerations?",  :input_html => {:rows => 8} %>

    <%= f.input :proposal, as: :text, :label => "How will these considerations be managed?",  :input_html => {:rows => 8} %>

    </div>
  </div>
  </div>

然后我有一个助手，它有我想要用于:子类别的输入：

module EthicsHelper
    def text_for_subcategory(category)
      if @ethic.category == 'Risk of harm'
            [ "Physical Harm", "Psychological distress or discomfort", "Social disadvantage", "Harm to participants", "Financial status", "Privacy"]
        elsif @ethic.category == 'Informed consent'
            ["Explanation of research", "Explanation of participant's role in research"]
        elsif @ethic.category == 'Anonymity and Confidentiality'
            ["Remove identifiers", "Use proxies", "Disclosure for limited purposes"]
        elsif @ethic.category == 'Deceptive practices'  
            "Feasibility"   
        else @ethic.category == 'Right to withdraw' 
            "Right to withdraw from participation in the project"   
       end
    end  

end

有人能看到我哪里出了问题吗？我希望类别值确定子类别的输入字段的值。

当我尝试这样做时，我会发现一个错误：

undefined method `category' for nil:NilClass

controller I有一个具有以下操作的项目控制器：

def new
    @project = Project.new
    @project.ethics.build

   def show



end



  end

  # GET /projects/1/edit
  def edit
     @project.ethics_build unless @project.ethics
  end

项目有许多伦理道德，伦理属于工程。

Answer 1

这就是你做错的事！在text_for_subcategory(category)方法中，将category传递给它，但在if语句中检查@ethic.category。在下面重写它应该是可行的。

module EthicsHelper
  def text_for_subcategory(category)
    if category == 'Risk of harm'
        [ "Physical Harm", "Psychological distress or discomfort", "Social disadvantage", "Harm to participants", "Financial status", "Privacy"]
    elsif category == 'Informed consent'
        ["Explanation of research", "Explanation of participant's role in research"]
    elsif category == 'Anonymity and Confidentiality'
        ["Remove identifiers", "Use proxies", "Disclosure for limited purposes"]
    elsif category == 'Deceptive practices'  
        "Feasibility"   
    else category == 'Right to withdraw' 
        "Right to withdraw from participation in the project"   
    end
  end
end

注意，在表单中调用@ethic.category时，已经将category传递到方法中，因此助手中的category只是充当占位符。

因此，在控制器中，根本没有设置@ethics。在edit方法中，需要设置@ethics，使其显示如下代码。

def show
  @ethics = @project.ethics_build unless @project.ethics
end

现在我的假设是，您已经在一个@project方法中设置了before_action。