Generate Thumbnail From pdf in rails paperclip

Question

How can I generate the first page of a pdf as a thumbnail in paperclip?

I tried a lot but it's not working

  has_attached_file :book_url, :styles => {
      :thumb => "100x100#",
      :small  => "150x150>",
      :medium => "200x200" }

This is giving the name of the pdf as a link but it's not giving the first page of the pdf

<%= link_to 'My PDF', @book.book_url.url %> 

Allerus

Answer 1

Tadas' answer is right, but for those who need more context, you can do something like this: The model below only creates thumbnails for certain kinds of files (e.g. it doesn't make thumbnails of audio files), but does make thumbnails for pdfs, image files, and video files:

class Record < ActiveRecord::Base
  print self # for logging on heroku

  belongs_to :user

  # Ensure user has provided the required fields
  validates :title, presence: true
  validates :file_upload, presence: true
  validates :description, presence: true

  # Use the has_attached_file method to add a file_upload property to the Record
  # class. 
  has_attached_file :file_upload,
    # In order to determine the styles of the image we want to save
    # e.g. a small style copy of the image, plus a large style copy
    # of the image, call the check_file_type method
    styles: lambda { |a| a.instance.check_file_type },

    processors: lambda { 
      |a| a.is_video? ? [ :ffmpeg ] : [ :thumbnail ] 
    }

  # Validate that we accept the type of file the user is uploading
  # by explicitly listing the mimetypes we are willing to accept
  validates_attachment_content_type :file_upload,
    :content_type => [
      "video/mp4", 
      "video/quicktime",

      "image/jpg", 
      "image/jpeg", 
      "image/png", 
      "image/gif",
      "application/pdf",

      "audio/mpeg", 
      "audio/x-mpeg", 
      "audio/mp3", 
      "audio/x-mp3", 

      "file/txt",
      "text/plain",

      "application/doc",
      "application/msword", 

      "application/vnd.ms-excel",     
      "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",

      "application/vnd.ms-powerpoint"
      ],
    :message => "Sorry! We do not accept the attached file type"

  # Before applying the Imagemagick post processing to this record
  # check to see if we indeed wish to process the file. In the case
  # of audio files, we don't want to apply post processing
  before_post_process :apply_post_processing?

  # Helper method that uses the =~ regex method to see if 
  # the current file_upload has a content_type 
  # attribute that contains the string "image" / "video", or "audio"
  def is_image?
    self.file_upload.content_type =~ %r(image)
  end

  def is_video?
    self.file_upload.content_type =~ %r(video)
  end

  def is_audio?
    self.file_upload.content_type =~ /\Aaudio\/.*\Z/
  end

  def is_plain_text?
    self.file_upload_file_name =~ %r{\.(txt)$}i
  end

  def is_excel?
    self.file_upload_file_name =~ %r{\.(xls|xlt|xla|xlsx|xlsm|xltx|xltm|xlsb|xlam|csv|tsv)$}i
  end

  def is_word_document?
    self.file_upload_file_name =~ %r{\.(docx|doc|dotx|docm|dotm)$}i
  end

  def is_powerpoint?
    self.file_upload_file_name =~ %r{\.(pptx|ppt|potx|pot|ppsx|pps|pptm|potm|ppsm|ppam)$}i
  end

  def is_pdf?
    self.file_upload_file_name =~ %r{\.(pdf)$}i
  end

  def has_default_image?
    is_audio?
    is_plain_text?
    is_excel?
    is_word_document?
  end

  # If the uploaded content type is an audio file,
  # return false so that we'll skip audio post processing
  def apply_post_processing?
    if self.has_default_image?
      return false    
    else
      return true
    end
  end

  # Method to be called in order to determine what styles we should
  # save of a file.
  def check_file_type
    if self.is_image?
      {
        :thumb => "200x200>", 
        :medium => "500x500>"
      }
    elsif self.is_pdf?
      {
        :thumb => ["200x200>", :png], 
        :medium => ["500x500>", :png]
      }

    elsif self.is_video?
      {
        :thumb => { 
          :geometry => "200x200>", 
          :format => 'jpg', 
          :time => 0
        }, 
        :medium => { 
          :geometry => "500x500>", 
          :format => 'jpg', 
          :time => 0
        }
      }
    elsif self.is_audio?
      {
        :audio => {
          :format => "mp3"
        }
      }
    else
      {}
    end
  end

end

Orton

I just used a stock placeholder image for powerpoint files. My designer made this: github.com/YaleDHLab/voices/blob/master/app/assets/images/… We used similar placeholder images for other file types, like Excel spreadsheets etc: github.com/YaleDHLab/voices/blob/master/app/assets/images/… – Orton

Answer 2

I think I once got it working by enforcing a file type, e.g.

:thumb => ["100x100#", :png]

of course it's not ideal, because it enforces this filetype for every upload

Apsis

no it's not working pdf is there so first we need to convert into the png of the first.it's giving only the name of the file that's it – Allerus

Answer 3

Thanks a million to @duhaime for his beautiful answer.

Since this is the most complete source of information I found to have PDF attached, I'd like to document it further:

Requirements:

• imagemagick
• ghostscript (I forgot about this one)
• (optional) ffmpeg if you want to handle video files

Also I replaced has_default_image? and apply_post_processing? with the single:

  def can_thumbnail?
    self.check_file_type.try(:{], :thumb).present?
  end

Finally I created a method for the not-thumbable attachments:

  def thumb
    return self.file.url(:thumb) if self.can_thumbnail?
    if self.is_video?
      '/thumb/video.png'
    else
      '/thumb/default.png'
    end
  end

But thanks again @duhaime

Adenoidal