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":{...}}'

Persistence

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.