Ruby on Rails form_for 创建空对象

Question

我的 alerts/views/ 文件夹中有一个名为 _form.html.erb 的部分。我从我的 agencies/views/ 文件夹中的显示页面呈现部分内容。

一切都正确呈现，部分确实创建了一个新警报，但警报完全是空的。

alerts_controller 创建方法

def create
  @alert = Alert.new(body: params[:body],
                   severity: params[:severity],
                   agency_id: @current_member.id)

    respond_to do |format|
      if @alert.save
        format.html { redirect_to @alert.agency, notice: 'Alert was successfully created.' }
        format.json { render :show, status: :created, location: @alert}
      else
        format.html { render :new }
        format.json { render json: @alert.errors, status: :unprocessable_entity }
      end
    end
  end

_form.html.erb

<%= form_for(Alert.new) do |f| %>
  <div class="input-group">
    <div class="field">
      <%= f.label :body %><br>
      <%= f.text_field :body %>
    </div>
    <div class="field">
      <%= f.label :severity %><br>
      <%= f.number_field :severity %>
    </div>
    <div class="action">
      <%= f.submit %>
    </div>
  </div>
<% end %>

没有错误，只是创建的警报完全是空的。主体、严重性和 agency_id 变量均为零。

我试过更换线路

<%= form_for(Alert.new) do |f| %>

有了这个：

<%= form_for(@alert) do |f| %>

并添加此行：

@alert = Alert.new

代理控制器中的显示方法。

但是无论哪种方式都会发生同样的事情。我做错了什么？

编辑

这是我点击提交时开始的日志，在 alerts.create 方法中加载重定向之前结束。

Started POST "/alerts" for ::1 at 2016-03-31 18:29:43 -0400
Processing by AlertsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"CgpepnYUec9uUoE/Ys6SAkOlzmK+w2q9IN782sXNoXnB3UyuegiS6m+W+mW+nXu4EIL8P8xH6JdigU8FfmzhVw==", "alert"=>{"body"=>"This is the body text", "severity"=>"12345"}, "commit"=>"Create Alert"}
  Account Load (0.1ms)  SELECT  "accounts".* FROM "accounts" WHERE "accounts"."id" = ? LIMIT 1  [["id", 7]]
  Agency Load (0.1ms)  SELECT  "agencies".* FROM "agencies" WHERE "agencies"."id" = ? LIMIT 1  [["id", 2]]
   (0.1ms)  begin transaction
  SQL (0.2ms)  INSERT INTO "alerts" ("agency_id", "created_at", "updated_at") VALUES (?, ?, ?)  [["agency_id", 2], ["created_at", "2016-03-31 22:29:43.014846"], ["updated_at", "2016-03-31 22:29:43.014846"]]
   (135.8ms)  commit transaction
  Agency Load (0.1ms)  SELECT  "agencies".* FROM "agencies" WHERE "agencies"."id" = ? LIMIT 1  [["id", 2]]
Redirected to http://localhost:3000/agencies/2
Completed 302 Found in 141ms (ActiveRecord: 136.2ms)

当我注释掉 alerts.create 方法并添加这一行时：

render plain: params

这是输出：

{"utf8"=>"✓", 
"authenticity_token"=>"3OfteFX41SV/5NxpTcKbP7AKhLm/ZKah+NXVn84e2xwXMP9wWeQ+AH4gpzORkXKF4y225M3gJIu6imZAdb+bMg==", 
"alert"=>{"body"=>"This is the body text.", "severity"=>"12345"},
"commit"=>"Create Alert", "controller"=>"alerts", "action"=>"create"}

Answer 1

从您的 params 调试中可以明显看出根本原因。 params 散列中有一个 alert 键。 alert 值是 body 和 severity.

的散列

在您的控制器中，您引用了 params[:body] 和 params[:severity]。那些应该是 params[:alert][:body] 和 params[:alert][:severity].

有没有理由不使用 Rails' 强参数？您可以重构为：

def create
  @alert = Alert.new(alert_params.merge(agency_id: @current_member.id)
  …
end
…

private

  def alert_params
    params.require(:alert).permit(:body, :severity)
  end

Answer 2

在 create method 参数中应该是这样的。

因为你的参数 "alert"=>{"body"=>"This is the body text.", "severity"=>"12345"}

def create
  @alert = Alert.new(body: params[:alert][:body],
                   severity: params[:alert][:severity],
                   agency_id: @current_member.id)

    respond_to do |format|
      if @alert.save
        format.html { redirect_to @alert.agency, notice: 'Alert was successfully created.' }
        format.json { render :show, status: :created, location: @alert}
      else
        format.html { render :new }
        format.json { render json: @alert.errors, status: :unprocessable_entity }
      end
    end
  end

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