Question

我一直试图弄清楚这个错误已经有一段时间了，并且已经看过类似的问题，但似乎仍无法解决这个问题。

这是添加用户权重的表单：

<%= form_for @weight do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="field">
    <%= f.text_field :weight, placeholder: "Enter weight" %>
  </div>
  <div class="field">
    <%= f.hidden_field :date, :value => Time.now %>
  </div>
  <%= f.submit "Add weight", class: "btn" %>  
<% end %>

控制器：

class WeightsController < ApplicationController
before_action :correct_user, only: [:create, :update, :destroy]

def new
  @weight = Weight.new
end

def create
  @weight = current_user.weights.build(weight_params)
  if @weight.save
    flash[:success] = "Weight added!"
    redirect_to current_user
  else
    flash[:notice] = "Can not add weight"
    redirect_to current_user
  end
end

def update
  @weight = current_user.weights.order("created_at").last
  if @weight.update_attributes(weight_params)
    flash[:success] = "Weight updated"
    redirect_to current_user
  else
    flash[:notice] = "Can not update weight"
    redirect_to current_user
  end

端

def edit
  @weight = Weight.find(params[:id])
end

def show
  @weight = current_user.weights.order("created_at").last
end

private

def weight_params
  params.require(:weight).permit(:weight, :date, :user_id)
end

def correct_user
  @user = User.find(params[:id])
  redirect_to(root_url) unless current_user?(@user)
end

端

我一直收到这个错误：

Completed 500 Internal Server Error in 13ms (ActiveRecord: 4.4ms)
2016-03-24T02:58:16.916469+00:00 app[web.1]: 
2016-03-24T02:58:16.916496+00:00 app[web.1]:
ActionView::Template::Error (First argument in form cannot contain nil or be empty):
2016-03-24T02:58:16.916497+00:00 app[web.1]:     1: <%= form_for @weight    do |f| %>
2016-03-24T02:58:16.916498+00:00 app[web.1]:     2:   <%= render 'shared/error_messages', object: f.object %>
2016-03-24T02:58:16.916499+00:00 app[web.1]:     3:   <div class="field">
2016-03-24T02:58:16.916499+00:00 app[web.1]:     4:     <%= f.label :weight, placeholder: "Enter weight" %>
2016-03-24T02:58:16.916500+00:00 app[web.1]:   app/views/shared/_add_weight_form.html.erb:1:in `_app_views_shared__add_weight_form_html_erb___3897731957600552245_69888716309360'

请注意，我还有一个重量的编辑表格：

<%= form_for @weight do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="field">
    <%= f.text_field :weight, placeholder: "Add weight" %>
  </div>
  <div class="field">
    <%= f.hidden_field :date, :value => Time.now %>
  </div>
  <%= f.submit "Update Weight", class: "btn btn-primary" %>  
<% end %>

这是我的新错误：

Started POST "/weights" for 98.7.88.139 at 2016-03-24 03:48:15 +0000
2016-03-24T03:48:15.107703+00:00 app[web.1]: Processing by      WeightsController#create as HTML
2016-03-24T03:48:15.107835+00:00 app[web.1]:   Parameters:       {"utf8"=>"✓",   "authenticity_token"=>"rpBU/21hOohssd2Cqbme8rZ0PbsxC3rz9cCW/kLEMJbZa4F6qFjBIRMSX9wpZSu/joOfvDgqLIitEshO6cL/kQ==", "weight"=>{"weight"=>"55",  "date"=>"2016-03-24 03:48:11 +0000"}, "commit"=>"Add weight"}
2016-03-24T03:48:15.110855+00:00 app[web.1]:   User Load (1.3ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1  [["id", nil]]
2016-03-24T03:48:15.112601+00:00 app[web.1]: Completed 404 Not Found in 5ms (ActiveRecord: 1.3ms)
2016-03-24T03:48:15.114746+00:00 app[web.1]: 
2016-03-24T03:48:15.114753+00:00 app[web.1]: ActiveRecord::RecordNotFound (Couldn't find User with 'id'=):
2016-03-24T03:48:15.114754+00:00 app[web.1]:   app/controllers/weights_controller.rb:55:in `correct_user'

Answer 1

以下是代码应该如下的代码：

新表格：

<%= form_for :weight do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="field">
    <%= f.text_field :weight, placeholder: "Enter weight" %>
    <%= hidden_field_tag :id, :value => current_user.id %>
  </div>
  <div class="field">
    <%= f.hidden_field :date, :value => Time.now %>
  </div>
  <%= f.submit "Add weight", class: "btn" %>  
<% end %>

编辑表单：

<%= form_for @weight do |f| %>
  <%= render 'shared/error_messages', object: f.object %>
  <div class="field">
    <%= f.text_field :weight, placeholder: "Add weight" %>
  </div>
  <div class="field">
    <%= f.hidden_field :date, :value => Time.now %>
    <%= hidden_field_tag :id, :value => current_user.id %>
  </div>
  <%= f.submit "Update Weight", class: "btn btn-primary" %>  
<% end %>

在这种情况下，通过将id字段作为隐藏字段添加到表单中，您将无法获得user.id nil error for create＆amp;更新方法和您的before_action过滤器将正常工作。 或你可以简单地删除更新＆amp;从before_action过滤器列表创建方法，如：

before_action :correct_user, only: [:destroy]

Answer 2

您要求控制器在创建时验证用户。但是在后期路线中没有params[:id]，即使有，也会有重量。

因此，如果您想验证用户，您可以在用户下嵌套权重，也可以使用会话来查找当前用户。（假设你正在使用Devise，对吧？）

因此，产生错误的原因是before_action过滤器。更改逻辑，或删除创建操作的过滤器

Form_for“表单中的第一个参数不能包含nil或为空”错误

2 个答案: