为什么使用form_for时它必须是current_user而不是@user

Question

谢谢你花时间停下来。我有一个问题，我很困惑，但希望得到更好的理解。在我过去的项目中，我能做到

<%= form_for @user, :html => { :multipart => true } do |f| %> 
<p class="editpage">Profile Picture: <%= f.file_field :avatar %></p> 
<%= f.submit %> 
<% end %> 

但在我目前的项目。当我使用@user时，当我尝试上传图片时，它会一直说要求的密码。我有我的用户控制器的私人参数中有：密码和：password_confirmation。目前，我想通了，上传的图片没有问题的唯一方法是用

<%= form_for current_user, :html => { :multipart => true } do |f| %> 
    <p class="editpage">Profile Picture: <%= f.file_field :avatar %></p> 
    <%= f.submit "Upload" %> 
<% end %> 

有人能帮助解释为什么这已发生。我很高兴它以某种方式工作，但我想更好地了解为什么它需要成为current_user而不是@user，因为我试图更新用户信息。感谢您的帮助和解释。

新增信息，我的ApplicationController内内终端

helper_method :current_user 


def current_user 
if session[:user_id] 
    @current_user = User.find(session[:user_id]) 
else 
    @current_user = nil 
end 
end 

错误

Started POST "/users" for 127.0.0.1 at 2015-08-25 02:04:55 +0900 
Processing by UsersController#create as HTML 
    Parameters: {"utf8"=>"✓", "authenticity_token"=>"e3DrDAhJPV4vgma9tg7wk9g589ZRDNInynWlXDv7oJQ=", "user"=> {"avatar"=>#<ActionDispatch::Http::UploadedFile:0x007f8784a00ec0 @tempfile=# <Tempfile:/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/RackMultipart20150825- 4587-14jh732>, @original_filename="10920917_10152994488342090_418253413398867864_n.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"user[avatar]\"; filename=\"10920917_10152994488342090_418253413398867864_n.jpg\"\r\nContent-Type: image/jpeg\r\n">}, "commit"=>"Upload"} 
Command :: file -b --mime '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c7 20150825-4587-1ka91nc.jpg' 
Command :: identify -format '%wx%h,%[exif:orientation]' '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c7 20150825-4587-1p9nueh.jpg[0]' 2>/dev/null 
Command :: identify -format %m '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh.jpg[0]' 
Command :: convert '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh.jpg[0]' -auto-orient -resize "200x200>" '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh20150825-4587-1alffdu' 
Command :: file -b --mime '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh20150825-4587-1alffdu' 
Command :: identify -format '%wx%h,%[exif:orientation]' '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh.jpg[0]' 2>/dev/null 
Command :: identify -format %m '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh.jpg[0]' 
Command :: convert '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh.jpg[0]' -auto-orient -resize "120x" -crop "120x120+0+20" +repage '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh20150825-4587-1kd13uh' 
Command :: file -b --mime '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh20150825-4587-1kd13uh' 
Command :: identify -format '%wx%h,%[exif:orientation]' '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh.jpg[0]' 2>/dev/null 
Command :: identify -format %m '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh.jpg[0]' 
Command :: convert '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh.jpg[0]' -auto-orient -resize "75x" -crop "75x75+0+12" +repage '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh20150825-4587-1recdb2' 
Command :: file -b --mime '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh20150825-4587-1recdb2' 
Command :: identify -format '%wx%h,%[exif:orientation]' '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh.jpg[0]' 2>/dev/null 
Command :: identify -format %m '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh.jpg[0]' 
Command :: convert '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh.jpg[0]' -auto-orient '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh20150825-4587-1vsru58' 
Command :: file -b --mime '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1p9nueh20150825-4587-1vsru58' 
    (0.4ms) begin transaction 
    Command :: file -b --mime '/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/47a027085753557774697c8014ad69c720150825-4587-1ksrnek.jpg' 
    (0.1ms) rollback transaction 
Redirected to http://localhost:3000/ 
Completed 302 Found in 625ms (ActiveRecord: 0.5ms) 

** UserController的*

class UsersController < ApplicationController 
def index 
    @user = User.new 
    @users = User.all 
    # if current_user 
    # @leaders = @current_user.leaders 
    # end 
end 

def create 
    @user = User.new(user_params) 
    if @user.save 
    session[:user_id] = @user.id 
    cookies[:user_id] = @user.id 
    flash[:notice] = "Successfully Registerd" 
    redirect_to "/" 
    else 
    flash[:alert] = @user.errors.full_messages 
    redirect_to "/" 
    end 
end 

def new 
    @user = User.new 
end 

def edit 
    @user = User.friendly.find(params[:id]) 
    current_user 
end 

def show 
    @user = User.friendly.find(params[:id]) 
    current_user 
    # if @current_user 
    # @followerlink = Follow.where(leader_id: @user.id, 
    #        follower_id: @current_user.id).first 
    # end 
end 

def update 
    @user = User.friendly.find(params[:id]) 
    if @user.update(user_params) 
    flash[:notice] = "You have successfully update your information" 
    redirect_to "/" 
    end 
end 

def destroy 
    @user = User.friendly.find(params[:id]) 
    @user.destroy 
end 


def user_params 
    params.require(:user).permit(:background, :username_or_email, :first_name, :last_name, :email, :password, :password_confirmation, :user_name, :avatar) 
end 
end 

UserModel

class User < ActiveRecord::Base 

    extend FriendlyId 
    friendly_id :user_name, use: :slugged 

    has_many :conversations, :foreign_key => :sender_id 
    after_create :create_default_conversation 

    has_attached_file :avatar, :styles => { 
    :medium => "200x200>", 
    :small => "120x120#", 
    :thumb => "75x75#", 
    :default_url => "http://www.adtechnology.co.uk/images/UGM-default-user.png" 
    } 

    validates_attachment_content_type :avatar, :content_type => /\Aimage\/.*\Z/ 

    has_attached_file :background, :styles => { 
    :medium => "200x200>", 
    :small => "120x120#", 
    :thumb => "75x75#", 
    :default_url => "http://www.adtechnology.co.uk/images/UGM-default-user.png" 
    } 

    validates_attachment_content_type :background, :content_type => /\Aimage\/.*\Z/ 

    validates :password, presence: true, on: :create 

end 

Answer 1

您正在使用此表单创建用户。

Processing by UsersController#create as HTML 

而既然你只是想添加一个化身，那么你就是想要做一个更新。您需要指定要向服务器发出的请求类型，因此请将:method => :PUT添加到您的表单中。

<%= form_for @user, :method => :PUT , :html => { :multipart => true } do |f| % 

此外，你需要有任何有密码的has_secure_password方法。 Read about it here。很高兴知道它是什么以及它做了什么。

has_secure_password 
validates :password, presence: true, allow_nil: true 

我增加了一个allow_nil: true，以便您可以更新而无需指定密码。你可以调试发生了什么你的变量

一种方法是使用inspect

例如：

@user.inspect 
    current_user.inspect 

如果你希望看到什么样的属性，你的模型，你可以使用它作为以及：

User.inspect 

Answer 2

您试图创建一个新用户，其参数看起来缺少适当的验证，所以提交正在回滚。

您的用户模式需要密码是存在于创建新用户：

Parameters: {"utf8"=>"✓", "authenticity_token"=>"e3DrDAhJPV4vgma9tg7wk9g589ZRDNInynWlXDv7oJQ=", "user"=> {"avatar"=>#<ActionDispatch::Http::UploadedFile:0x007f8784a00ec0 @tempfile=# <Tempfile:/var/folders/83/2r02tq2d3934d30syfmpz9yw0000gn/T/RackMultipart20150825- 4587-14jh732>, @original_filename="10920917_10152994488342090_418253413398867864_n.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"user[avatar]\"; filename=\"10920917_10152994488342090_418253413398867864_n.jpg\"\r\nContent-Type: image/jpeg\r\n">}, "commit"=>"Upload"} 

：

validates :password, presence: true, on: :create 

然而，发生故障的请求（从您发布的终端错误）没有密码传递

如果您修改控制器的新动作：

高清新 @user = User.new（密码： “一些密码”） 结束

，然后把@user在你的form_for调用，它应该工作。

编辑：我假设您正在寻找创建操作，但是，我认为Hristo Georgiev提供了正确的解决方案。