Method: Paperclip::ClassMethods#has_attached_file

Defined in:
lib/paperclip.rb

- (Object) has_attached_file(name, options = {})

has_attached_file gives the class it is called on an attribute that maps to a file. This is typically a file stored somewhere on the filesystem and has been uploaded by a user. The attribute returns a Paperclip::Attachment object which handles the management of that file. The intent is to make the attachment as much like a normal attribute. The thumbnails will be created when the new file is assigned, but they will not be saved until save is called on the record. Likewise, if the attribute is set to nil is called on it, the attachment will not be deleted until save is called. See the Paperclip::Attachment documentation for more specifics. There are a number of options you can set to change the behavior of a Paperclip attachment:

  • url: The full URL of where the attachment is publically accessible. This can just as easily point to a directory served directly through Apache as it can to an action that can control permissions. You can specify the full domain and path, but usually just an absolute path is sufficient. The leading slash must be included manually for absolute paths. The default value is “/system/:class/:attachment/:id_partition/:style/:filename”. See Paperclip::Attachment#interpolate for more information on variable interpolaton.

    :url => "/:class/:attachment/:id/:style_:filename"
    :url => "http://some.other.host/stuff/:class/:id_:extension"
  • default_url: The URL that will be returned if there is no attachment assigned. This field is interpolated just as the url is. The default value is “/:attachment/:style/missing.png”

    has_attached_file :avatar, :default_url => "/images/default_:style_avatar.png"
    User.new.avatar_url(:small) # => "/images/default_small_avatar.png"
  • styles: A hash of thumbnail styles and their geometries. You can find more about geometry strings at the ImageMagick website (www.imagemagick.org/script/command-line-options.php#resize). Paperclip also adds the “#” option (e.g. “50x50#”), which will resize the image to fit maximally inside the dimensions and then crop the rest off (weighted at the center). The default value is to generate no thumbnails.

  • default_style: The thumbnail style that will be used by default URLs. Defaults to original.

    has_attached_file :avatar, :styles => { :normal => "100x100#" },
                      :default_style => :normal
    user.avatar.url # => "/avatars/23/normal_me.png"
  • keep_old_files: Keep the existing attachment files (original + resized) from being automatically deleted when an attachment is cleared or updated. Defaults to false.

  • preserve_files: Keep the existing attachment files in all cases, even if the parent record is destroyed. Defaults to false.

  • whiny: Will raise an error if Paperclip cannot post_process an uploaded file due to a command line error. This will override the global setting for this attachment. Defaults to true.

  • convert_options: When creating thumbnails, use this free-form options array to pass in various convert command options. Typical options are “-strip” to remove all Exif data from the image (save space for thumbnails and avatars) or “-depth 8” to specify the bit depth of the resulting conversion. See ImageMagick convert documentation for more options: (www.imagemagick.org/script/convert.php) Note that this option takes a hash of options, each of which correspond to the style of thumbnail being generated. You can also specify :all as a key, which will apply to all of the thumbnails being generated. If you specify options for the :original, it would be best if you did not specify destructive options, as the intent of keeping the original around is to regenerate all the thumbnails when requirements change.

    has_attached_file :avatar, :styles => { :large => "300x300", :negative => "100x100" }
                               :convert_options => {
                                 :all => "-strip",
                                 :negative => "-negate"
                               }

    NOTE: While not deprecated yet, it is not recommended to specify options this way. It is recommended that :convert_options option be included in the hash passed to each :styles for compatibility with future versions. NOTE: Strings supplied to :convert_options are split on space in order to undergo shell quoting for safety. If your options require a space, please pre-split them and pass an array to :convert_options instead.

  • storage: Chooses the storage backend where the files will be stored. The current choices are :filesystem, :fog and :s3. The default is :filesystem. Make sure you read the documentation for Paperclip::Storage::Filesystem, Paperclip::Storage::Fog and Paperclip::Storage::S3 for backend-specific options.

It's also possible for you to dynamically define your interpolation string for :url, :default_url, and :path in your model by passing a method name as a symbol as a argument for your has_attached_file definition:

class Person
  has_attached_file :avatar, :default_url => :default_url_by_gender

  private

  def default_url_by_gender
    "/assets/avatars/default_#{gender}.png"
  end
end


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# File 'lib/paperclip.rb', line 183

def has_attached_file(name, options = {})
  HasAttachedFile.define_on(self, name, options)
end

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