[Gem]圖片上傳-Carrierwave

4.增加欄位到model

rails g migration add_image_to_img imgurl(需要用到上傳的那個model)

5. DB Migrate

rake db:migrate

6.修改model

mount_uploader :imgurl, ImgUploade

7.加入form

<%= f.file_field :imgurl  %>

8.完成即可顯示圖片：

image_tag(@foo.imgurl_url)
或
image_tag(@foo.imgurl_url(:thumb)) #取得壓縮的圖檔，搭配補充3

補充設定：

1.縮圖設定：

vi app/uploaders/image_uploader.rb

2.將include CarrierWave::MiniMagick前面的註解拿掉(本例是使用MiniMagick，使用前需先下載)

於app/uploaders/img_uploader.rb修改：

# Include RMagick or MiniMagick support:
# Include CarrierWave::RMagick
include CarrierWave::MiniMagick

3.修改縮圖大小:

於app/uploaders/img_uploader.rb加入：
version :thumb do
  process :resize_to_fit => [50, 50]
end

version :rectangle do
  process :resize_to_fit => [300, 300]
end

4.只允許上傳圖片

於app/uploaders/img_uploader.rb加入：
def extension_white_list
    %w(jpg jpeg gif png)
end

5.修改儲存路徑

於app/uploaders/img_uploader.rb加入：

def store_dir
    'public/my/upload/directory'
end

Carriewaveupload GitHub

參考文章1

參考文章2