Rails 上传图片

1.新建一个项目

    rails new avatar

2.在项目的Gemfile中添加：

gem 'carrierwave'  gem 'mini_magick'  

3.建立一个model

  rails g model user name:string email:string

4.建一个controller

  rails g controller users

5.为users表添加一个avatar字段

  rails g migration add_avatar_to_users avatar:string

6.rake db:migrate

7.生成Avatar

 rails generate uploader Avatar #将会生成文件app/uploaders/avatar_uploader.rb

8.为user的model user.rb添加如下代码，使表之间关联

 mount_uploader :avatar, AvatarUploader

9.接下来进行修改app/uploaders/avatar_uploader.rb

# encoding: utf-8class AvatarUploader < CarrierWave::Uploader::Base  # Choose what kind of storage to use for this uploader:   storage :file  # storage :fog  # Override the directory where uploaded files will be stored.  # This is a sensible default for uploaders that are meant to be mounted:  def store_dir  #定义上传到哪个文件夹下      "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"    end    def default_url  #可以定义默认图片，如过用户没有上传图片，则可以使用默认的图片    "avatar/#{version_name}.png"    end  # Add a white list of extensions which are allowed to be uploaded.  # For images you might use something like this:  def extension_white_list      %w(jpg jpeg gif png)     end  

10.添加routes

  resources :users

11.在user_controller.rb中

 def index        @users = User.all    end    def new        @user = User.new    end    def create        @user = User.new(user_params)        @user.save        redirect_to user_index_path    end    # def update    #     @user = User.find(params[:id])    #     @user.update(user_params)    #     redirect_to user_path    # end    private        def user_params            params.require(:user).permit(:name,:email,:avatar)        endend

12.views/user/

index.html.erb<% @users.each do |user| %>  <%= user.name%>  <%= image_tag user.avatar_url if user.avatar %><%end %>new.html.erb<%= form_for @user, :url=>user_index_path do |f| %>  <div class="field">    <%= f.label :name %>    <%= f.text_field :name %><hr/>    <%= f.file_field :avatar %>    <%= f.hidden_field :avatar_cache %>  </div><hr/>  <%= f.submit %><%end%>