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Sequel

The sequel plugin adds Sequel integration to the attachment interface. It is built on top of the model plugin.

Shrine.plugin :sequel

Attachment

Including a Shrine::Attachment module into a Sequel::Model subclass will:

• add model attachment methods
• add validations and hooks to tie attachment process to the record lifecycle

class Photo < Sequel::Model # has `image_data` column 
  include ImageUploader::Attachment(:image) # adds methods, callbacks & validations 
end

photo = Photo.new
 
photo.image = file # cache attachment 
 
photo.image      #=> #<Shrine::UploadedFile id="bc2e13.jpg" storage=:cache ...> 
photo.image_data #=> '{"id":"bc2e13.jpg","storage":"cache","metadata":{...}}' 
 
photo.save # persist, promote attachment, then persist again 
 
photo.image      #=> #<Shrine::UploadedFile id="397eca.jpg" storage=:store ...> 
photo.image_data #=> '{"id":"397eca.jpg","storage":"store","metadata":{...}}' 
 
photo.destroy # delete attachment 
 
photo.image.exists? #=> false 

Hooks

After Save

After a record is saved and the transaction is committed, Attacher#finalize is called, which promotes cached file to permanent storage and deletes previous file if any.

photo = Photo.new
 
photo.image = file
photo.image.storage_key #=> :cache 
 
photo.save
photo.image.storage_key #=> :store 

After Destroy

After a record is destroyed and the transaction is committed, Attacher#destroy_attached method is called, which deletes stored attached file if any.

photo = Photo.find(photo_id)
photo.image #=> #<Shrine::UploadedFile> 
photo.image.exists? #=> true 
 
photo.destroy
photo.image.exists? #=> false 

Overriding hooks

You can override any of the following attacher methods to modify callback behaviour:

• Attacher#sequel_before_save
• Attacher#sequel_after_save
• Attacher#sequel_after_destroy

class Shrine::Attacher
  def sequel_after_save
    super
    # ... 
  end
end

Skipping Hooks

If you don't want the attachment module to add any hooks to your model, you can set :hooks to false:

plugin :sequel, hooks: false

Validations

If you're using the validation plugin, the attachment module will automatically merge attacher errors with model errors.

class ImageUploader < Shrine
  plugin :validation_helpers
 
  Attacher.validate do
    validate_max_size 10 * 1024 * 1024
  end
end

photo = Photo.new
photo.image = file
photo.valid?
photo.errors #=> { image: ["size must not be greater than 10.0 MB"] } 

Attachment Presence

If you want to validate presence of the attachment, you can use Sequel's presence validator:

class Photo < Sequel::Model
  include ImageUploader::Attachment(:image)
 
  def validate
    super
    validates_presence :image
  end
end

Skipping Validations

If don't want the attachment module to merge file validations errors into model errors, you can set :validations to false:

plugin :sequel, validations: false

Attacher

You can also use Shrine::Attacher directly (with or without the Shrine::Attachment module):

class Photo < Sequel::Model # has `image_data` column 
end

photo    = Photo.new
attacher = ImageUploader::Attacher.from_model(photo, :image)
 
attacher.assign(file) # cache 
 
attacher.file    #=> #<Shrine::UploadedFile id="bc2e13.jpg" storage=:cache ...> 
photo.image_data #=> '{"id":"bc2e13.jpg","storage":"cache","metadata":{...}}' 
 
photo.save        # persist 
attacher.finalize # promote 
photo.save        # persist 
 
attacher.file    #=> #<Shrine::UploadedFile id="397eca.jpg" storage=:store ...> 
photo.image_data #=> '{"id":"397eca.jpg","storage":"store","metadata":{...}}' 

Pesistence

The following persistence methods are added to Shrine::Attacher:

Method	Description
Attacher#atomic_promote	calls Attacher#promote and persists if the attachment hasn't changed
Attacher#atomic_persist	saves changes if the attachment hasn't changed
Attacher#persist	saves any changes to the underlying record

See persistence docs for more details.