Use paperclip to upload images

Currently, the two most popular Image Upload extensions on rails are fleximage and paperclip. If you only process images in one breath, it is fleximage, of course, but if you still need other MP3, FLV, and other attachments for multi-State Association, then select paperclip. In general, paperclip is much better than the older upload plug-ins, such as acts_as_attachment, attachment_fu, and file_column.

Installation support

This plug-in requires external support for rmagick and ImageMagick. For installation instructions, refer to my other article.

Install paperclip

 
Ruby script/plugin install git: // github.com/thoughtbot/paperclip.git
 

Build the main framework

Two modules are involved: user and photo. We use user_id to differentiate albums.

Mysql> Create Database scripts; rails album-D mysqlcd album Ruby script/plugin install git: // your script/generate authenticated user sessions Ruby script/generate scaffold photo User: belongs_to is_avatar: Boolean
 

Configure the username and password of database. yml In the config directory.

The next step is very important. We need to add the attachment upload capability to photo.

 
Ruby script/generate paperclip photo imagerake DB: migrate
 

We name the attachment image, so that paperclip adds four prefixes to the photo model: <attachment> _ (the name of the attachment we just gave) <attachment> _ file_name, <attachment> _ file_size, <attachment> _ content_type, and <attachment> _ updated_at), that is, image_file_name, image_file_size, image_content_type, and metadata.

Delete index.html under the publicdirectory and add the routing rules:

Map. Root: Users
 

Modify users_controller and add index action

 
Def index; End
 

Add View

 
<% = Link_to "album", photos_path %>
 

Modify _user_bar.html. ERB

 
<Div id = "user_bar"> <% if logged_in? %> <% = Link_to "logout", logout_path,: Title => "logout" %> <% = link_to "Welcome, <strong >#{ current_user.login} </strong> ", CURRENT_USER %> <% else %> <% = link_to" login ", login_path ,: title => "login" %> <% = link_to "register", signup_path,: Title => "register" %> <% end %> </div>
 

Template application.html. ERB and global assistant layout_helper.rb

 
     
   
   <% = javascript_include_tag: Defaults %>  <% = H (yield (: Title) | controller. action_name) %>  <% = stylesheet_link_tag 'blueprint', 'application' %> <% = yield (: Head) %>   
  
  

   
    <%-flash. each do | Name, MSG |-%> <% = content_tag: div, MSG ,: class => "# {name}" %> <%-end-%> <%-If show_title? -%> 
   
   
 <% = H yield (: Title) %> 
 <%-end-%> <% = render: partial => "users/user_bar" %> <% = yield %> 
  
  
   

Module layouthelper def title (page_title, show_title = true) @ content_for_title = page_title.to_s @ show_title = show_title end def show_title? @ Show_title endend
 

Modify application_controller

 
Class applicationcontroller: record_not_found protected def record_not_found render: file => file. Join (rails_root, 'public', '404.html '),: Status => 404 endend
 

Start the server and create a user named situ zhengmei. We need to use its ID.

Modify the photo module to implement the upload capability.

New _form.html. ERB

<% Form_for @ photo,: HTML =>{: multipart => true} Do | f |%> <% = f. error_messages %> <% if logged_in? %> <% = F. hidden_field: user_id,: value => current_user.id %> <% end %> <p> <% = f. label: is_avatar %> <br/> <% = f. check_box: is_avatar %> </P> <p> <% = f. file_field: Image %> </P> <p> <button type = "Submit"> <% = button_name %> </button> </P> <% end %>
 

Modify new.html. ERB

 
<% Title "Upload image" %> <% = render: Partial => 'form',: locals => {: button_name => "Upload" }%> <% = link_to 'back', photos_path,: class => "button" %>
 

Modify show.html. ERB

<Div class = "figure"> <% = image_tag @ photo. image. url,: ALT => "it is in harmony with GFW! "%> <Div class =" legend "> All: <% = H @ photo. user. login %>; whether it is an Avatar: <% = @ photo. is_avatar %> </div> <% = link_to 'edit', [: Edit, @ photo],: class => "button" %> <% = link_to 'Return', photos_path,: class => "button" %>
 

Modify photo. Rb

Class photo
 
So that it can run, very simple!
 
Upload images through URLs
 
Ruby script/generate migration addimageremoteurltophoto image_remote_url: stringrake DB: migrate
 
 
Modify the photo Model
 
Require 'open-Uri 'class photo: image_url_provided? Validates_presence_of: image_remote_url,: If =>: image_url_provided ?, : Message => 'invalid address 'private def image_url_provided? ! Self. image_url.blank? End def download_remote_image self. image = do_download_remote_image self. image_remote_url = image_url end def do_download_remote_image IO = open (URI. parse (image_url) def Io. original_filename; base_uri.path.split ('/'). last; end Io. original_filename.blank? ? Nil: Io rescue # Catch URL errors with validations instead of exceptions (errno: enoent, openuri: httperror, Etc...) endend
 
 
Modify _form.html. ERB
 
<% Form_for @ photo,: HTML =>{: multipart => true} Do | f |%> <% = f. error_messages %> <% if logged_in? %> <% = F. hidden_field: user_id,: value => current_user.id %> <% end %> <% if action_name = "new" %> <p> <% = f. label: is_avatar, "whether to be an avatar" %> <% = f. check_box: is_avatar %> </P> <% end %> <p> <% = f. file_field: Image %> <br/> or URL <% = f. text_field: image_url %> </P> <p> <button type = "Submit"> <% = button_name %> </button> </P> <% end %>
 
 
 
 
The upload is successful!
 
 
 
 
Add multiple styles and Verification
 
#........................ Has_attached_file: image,: default_url => "/images/rails.png",: styles =>{: thumb => "100x100 #",: gallery => "150x150>",: Avatar => "200x200>"} # The image cannot be deleted with this option # validates_attachment_presence: Image validates_attachment_size: image ,: less_than => 5. megabytes validates_attachment_content_type: image,: content_type => ['image/gif', 'image/PNG ', 'image/X-PNG', 'image/JPEG ', 'image/pjpeg ', 'image/jpg'] #........................
 
Delete Image
 
Because paperclip stores uploaded items on the hard disk by default, calling destroy action can only delete the data in the database, but cannot delete the related images. Therefore, we need to add the image deletion logic to the model.
 
#================================== OthersCode========================================================== ============== Delete an image ====================================== def delete_image = (value) @ delete_image =! Value. to_ I .zero? End def delete_image !! @ Delete_image end alias_method: delete_image ?, : Delete_image before_validation: clear_image def clear_image self. Image = nil if delete_image? &&! Image. Dirty? End #================================== other code ====== ====================
 
 
Modify _form.html. ERB
 
<% Form_for @ photo,: HTML =>{: multipart => true} Do | f |%> <% = f. error_messages %> <% if logged_in? %> <% = F. hidden_field: user_id,: value => current_user.id %> <% end %> <% if action_name = "new" %> <p> <% = f. label: is_avatar, "whether to be an avatar" %> <% = f. check_box: is_avatar %> </P> <% end %> <p> <% = f. file_field: Image %> <br/> or URL <% = f. text_field: image_url %> </P> <%-unless @ photo. new_record? |! @ Photo. image? -%> <Div> <% = image_tag (@ photo. image. URL (: Gallery),: ALT => 'photo',: Title => 'current image') %> <p> <% = f. label (: delete_image, 'delete image') %> <% = f. check_box (: delete_image) %> </P> </div> <%-end-%> <p> <button type = "Submit"> <% = button_name %> </button> </ p> <% end %>
 
Modify edit.html. ERB
 
<% Title "Edit image" %> <% = render: Partial => 'form',: locals => {: button_name => "Update" }%> <% = link_to 'enlarge ', @ photo,: class => "button" %> <% = link_to' Return ', photos_path ,: class => "button" %>
 
 
Modify update action
 
 
Def update @ photo = photo. Find (Params [: Id]) If @ photo. update_attributes (Params [: Photo]) Message = @ photo. delete_image ?? "Image deleted! ":" Image updated! "Flash [: Notice] = message redirect_to (@ photo) else render: Action =>" edit "end
 
<H1> listing photos  
 
 
 
Finally, paperclip is unfriendly to Windows. The most common problem in the Google discussion group is the "is not recognized by the 'identify' command" error, however, I have never met this blog post. It is absolutely no problem in the Linux environment.