Ruby on rails 轨道3和托架波形：can'；t将nil转换为字符串

我试图在rails应用程序中使用carrierwave gem实现上传图像，但当我按下表单的提交按钮时，我收到了以下错误：“无法将nil转换为字符串”

应用程序跟踪：

app/controllers/uploads_controller.rb:48:in `new'
app/controllers/uploads_controller.rb:48:in `create'

请求：

{"utf8"=>"✓",
"authenticity_token"=>"VsgoOE/BQwwT0aQRRMO22kxdPgC/BS2H/CnHVBi4Cfw=",
"upload"=>{"name"=>"aaa",
"description"=>"aa",
"image"=>[#<ActionDispatch::Http::UploadedFile:0x508a8b0 @original_filename="c1147374806dce0ec967015c041fec3b.jpg",
@content_type="image/jpeg",
@headers="Content-Disposition: form-data; name=\"upload[image][]\"; filename=\"c1147374806dce0ec967015c041fec3b.jpg\"\r\nContent-Type: image/jpeg\r\n",
@tempfile=#<File:C:/Users/user/AppData/Local/Temp/RackMultipart20150621-5356-1gm0atx>>]},
"commit"=>"Upload"}

carrierwave保存图像的目录：

public
    uploads
        upload
            image
                1
                ...

应用程序跟踪引用的第48行是

@upload=upload.new（params[：upload]）

如何解决此问题？ 我不明白为什么上传是

nil

。 有人能帮我找到正确的方法吗

一些细节：OS Win7 Pro、Rails v.3.2.21、Carrierwave v.0.10.0、IDE Rubymine v.7.1.2

编辑1： 根据@sreena的建议，我从上传切换到图像，现在这是请求消息：

Parameters: {"utf8"=>"✓",
"authenticity_token"=>"G1zpdyCbXRJYqAR5m5hscMjQOry85KN7toNhJznOFok=",
"upload"=>{"name"=>"titolo", "description"=>"descrizione",
"image"=>[#<ActionDispatch::Http::UploadedFile:0x534aef0 @original_filename="2.jpg", 
@content_type="image/jpeg", @headers="Content-Disposition: form-data;
name=\"upload[image][]\"; filename=\"2.jpg\"\r\nContent-Type: image/jpeg\r\n",
@tempfile=#<File:C:/Users/user/AppData/Local/Temp/RackMultipart20150624-4180-14oypoq>>]},
"commit"=>"Upload"}

参数：{“utf8”=>“✓",
“真实性令牌”=>“G1zpdyCbXRJYqAR5m5hscMjQOry85KN7toNhJznOFok=“，
“上传”=>{“名称”=>“标题”、“说明”=>“说明”，
“图像”=>[#]}，
“提交”=>“上载”}

---

按下submit按钮后，现在我收到表单中出现的另一个错误：

“图像不能为空”

您应该像这样在控制器中传递创建参数

@upload=upload.new（参数[：图像]）

---

，它应该是图像不上传

在上传者页面中添加此功能

def上传参数
参数require（：upload）.permit（：image，：name，：description）
结束

在def中创建如下添加

def创建
@上传=上传。新建（上传参数）
@upload.user\u id=当前用户id
回应待办事项|格式|
如果@upload.save

            format.html { redirect_to @upload, notice: 'Image was uploaded.' }
            format.json { render json: @upload, status: :created, location: @upload }

        else
            format.html { render action: "new" }
            format.json { render json: @upload.errors, status: :unprocessable_entity }
        end
    end
end

---

最后我解决了这个问题。 我只是用以下方式更改create方法

def create
    @upload =  current_user.uploads.build(params[:upload])
    @upload.image = params[:upload]["image"]
    respond_to do |format|
    if @upload.save

        format.html { redirect_to @upload, notice: 'Image was uploaded.' }
        format.json { render json: @upload, status: :created, location: @upload }

    else
        format.html { render action: "new" }
        format.json { render json: @upload.errors, status: :unprocessable_entity }
    end
end

---

我听从了你的建议，但现在我收到了一条新的错误消息：“图像不能为空”（当我按下提交按钮时）。它似乎无法识别图像。编辑中的新请求错误。很抱歉延迟，当我尝试上载图像时，添加了该功能，但我收到消息“无法将nil转换为字符串”“，所以我认为这应该是一个gem版本的问题。无论如何，谢谢你的建议！

create_table "uploads", :force => true do |t|
    t.string   "name"
    t.string   "description"
    t.integer  "user_id"
    t.datetime "created_at",  :null => false
    t.datetime "updated_at",  :null => false
    t.string   "image"
end

public
    uploads
        upload
            image
                1
                ...

Parameters: {"utf8"=>"✓",
"authenticity_token"=>"G1zpdyCbXRJYqAR5m5hscMjQOry85KN7toNhJznOFok=",
"upload"=>{"name"=>"titolo", "description"=>"descrizione",
"image"=>[#<ActionDispatch::Http::UploadedFile:0x534aef0 @original_filename="2.jpg", 
@content_type="image/jpeg", @headers="Content-Disposition: form-data;
name=\"upload[image][]\"; filename=\"2.jpg\"\r\nContent-Type: image/jpeg\r\n",
@tempfile=#<File:C:/Users/user/AppData/Local/Temp/RackMultipart20150624-4180-14oypoq>>]},
"commit"=>"Upload"}

            format.html { redirect_to @upload, notice: 'Image was uploaded.' }
            format.json { render json: @upload, status: :created, location: @upload }

        else
            format.html { render action: "new" }
            format.json { render json: @upload.errors, status: :unprocessable_entity }
        end
    end
end

def create
    @upload =  current_user.uploads.build(params[:upload])
    @upload.image = params[:upload]["image"]
    respond_to do |format|
    if @upload.save

        format.html { redirect_to @upload, notice: 'Image was uploaded.' }
        format.json { render json: @upload, status: :created, location: @upload }

    else
        format.html { render action: "new" }
        format.json { render json: @upload.errors, status: :unprocessable_entity }
    end
end