rails在Windows上生成scaffold命令导致ArgumentError

Question

我使用"rails generate scaffold project"创建了一个新的web应用程序。我过去已经在运行其他版本rails和ruby的Linux和Mac OSX上做过这件事，一切都很好，但这次我在Windows 7上工作。这是我的环境

C:Usersuser1Company>ruby -v
ruby 2.0.0p451 (2014-02-24) [x64-mingw32]
C:Usersuser1Company>rails -v
DL is deprecated, please use Fiddle
Rails 4.1.0
C:Usersuser1Company>

在运行scaffold命令后，我运行了rakedb:migrate，并成功创建了我的第一个项目。然后我可以编辑项目，但当我点击更新时，我会收到以下错误消息

ArgumentError (When assigning attributes, you must pass a hash as an argument.):

完整的服务器日志消息

Started PATCH "/projects/1" for 127.0.0.1 at 2014-04-29 05:16:33 -0700
Processing by projectsController#update as HTML
  Parameters: {"utf8"=>"√", "authenticity_token"=>"gST6BUQNwOZQDYVj60DXLuFANv1JsM02YAIM+xYwt/M=", "commit"=>"Update project", "id"=>"1"}
  project Load (0.0ms)  SELECT  "projects".* FROM "projects"  WHERE "projects"."id"= ? LIMIT 1  [["id", 1]]
   (1.0ms)  begin transaction
   (0.0ms)  rollback transaction
Completed 500 Internal Server Error in 10ms
ArgumentError (When assigning attributes, you must pass a hash as an argument.):
  app/controllers/projects_controller.rb:44:in `block in update'
  app/controllers/projects_controller.rb:43:in `update'
  Rendered C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/actionpack-4.1.0/lib/action_dispatch/middleware/templates/rescues/_source.erb (2.0ms)
  Rendered C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/actionpack-4.1.0/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb (2.0ms)
  Rendered C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/actionpack-4.1.0/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (2.0ms)
  Rendered C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/actionpack-4.1.0/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (104.0ms)

这是我的"更新"方法(由scaffold命令自动创建(

# PATCH/PUT /projects/1
# PATCH/PUT /projects/1.json
def update
  respond_to do |format|
    if @project.update(project_params)
      format.html { redirect_to @project, notice: 'Update Successful!' }
      format.json { render :show, status: :ok, location: @project }
    else
      format.html { render :edit }
      format.json { render json: @project.errors, status: :unprocessable_entity }
    end
  end
end

我尝试删除"PATCH/"关键字，但没有成功。我用以下方法替换了整个方法(这对我的另一个应用程序有效，但这次在Windows上无效(

# PATCH/PUT /projects/1
# PATCH/PUT /projects/1.json
def update
  @project = Project.find(params[:id])
  if @project.update_attributes(params[:project])
    flash[:notice] = "Update Successful!"
  end
  respond_with(@project)
end

但这并没有什么区别。

我也尝试过(我通过浏览SO找到了这个(

# PUT /projects/1
# PUT /projects/1.json
def update
  @project = Project.find(params[:id])
  respond_to do |format|
    if @project.update_attributes(params[:project])
      format.html { redirect_to @project, notice: 'Update Successful!' }
      format.json { head :ok }
    else
      format.html { render action: "edit" }
      format.json { render json: @project.errors, status: :unprocessable_entity }
    end
  end

但也没有成功

以下是其他工作方法(都是由"rails generate scaffold"命令自动生成的，它们都工作得很好(

# GET /projects
# GET /projects.json
def index
  @projects = project.all
end
# GET /projects/1
# GET /projects/1.json
def show
end
# GET /projects/new
def new
  @project = project.new
end
# GET /projects/1/edit
def edit
end
# POST /projects
# POST /projects.json
def create
  @project = project.new(project_params)
  respond_to do |format|
    if @project.save
      format.html { redirect_to @project, notice: 'Creation Successful!' }
      format.json { render :show, status: :created, location: @project }
    else
      format.html { render :new }
      format.json { render json: @project.errors, status: :unprocessable_entity }
    end
  end
end

为什么"rails generate scaffold"命令在Windows上不起作用，而在Linux和Mac OSX上运行良好？

更新1

以下是由"rails generate scaffold"命令自动创建的其他方法

class ProjectsController < ApplicationController
  before_action :set_project, only: [:show, :edit, :update, :destroy]
  <other methods listed above : index, show, new, edit, create, update, and destroy>
  private
    # Use callbacks to share common setup or constraints between actions.
    def set_project
      @project = Project.find(params[:id])
    end
    # Never trust parameters from the scary internet, only allow the white list through.
    def project_params
      params[:project]
    end
end

进行Kirti Thorat建议的更改后的工作代码

这就是对我有效的

# PATCH/PUT /projects/1
# PATCH/PUT /projects/1.json
def update
@project = Project.find(params[:id])
  respond_to do |format|
    if @project.update(project_params)
      format.html { redirect_to @project, notice: 'Project was successfully updated.' }
      format.json { render :show, status: :ok, location: @project }
    else
      format.html { render :edit }
      format.json { render json: @project.errors, status: :unprocessable_entity }
    end
  end
end
private
  # Use callbacks to share common setup or constraints between actions.
  def set_project
    @project = Project.find(params[:id])
  end
  # Never trust parameters from the scary internet, only allow the white list through.
  def project_params
    params.require(:project).permit(:UnitMgtAddress)
  end

Answer 1

您刚刚创建了一个没有任何其他字段的scaffold。因此，projects表只有3个默认字段id、created_at和updated_at。因为在你的update行动中，当你这样做时：

if @project.update(project_params)

或

if @project.update_attributes(params[:project])

您会得到错误，因为update和update_attributes需要一个Hash作为参数，而params[:project]为零。查看服务器日志中的params哈希

{"utf8"=>"√", "authenticity_token"=>"gST6BUQNwOZQDYVj60DXLuFANv1JsM02YAIM+xYwt/M=", "commit"=>"Update project", "id"=>"1"}

它没有密钥project

可能的解决方案

不添加新字段

如果您不打算在projects表中添加任何新字段，那么进行update操作是没有意义的，因为您将更新哪个字段？

添加新字段

您可以根据需要向projects表中添加新字段，如name、duration等(通过创建迁移来添加新字段(。

之后，您只需要更新project_params方法，如下所示：

def project_params
  params.require(:project).permit(:name, :duration)
end