Form Assign

The form_assign plugin allows attaching file from form params without a form object.

plugin :form_assign

The Attacher#form_assign method will detect the file param and assign it to the attacher:

attacher = photo.image_attacher
attacher.form_assign({ "image" => file, "title" => "...", "description" => "..." })
attacher.file #=> #<Shrine::UploadedFile>

It works with remote_url, data_uri, and remove_attachment plugins:

# remote_url plugin
attacher.form_assign({ "image_remote_url" => "https://example.com/..." })
attacher.file #=> #<Shrine::UploadedFile>

# data_uri plugin
attacher.form_assign({ "image_data_uri" => "data:image/jpeg;base64,..." })
attacher.file #=> #<Shrine::UploadedFile>

# remove_attachment plugin
attacher.form_assign({ "remove_image" => "1" })
attacher.file #=> nil

The return value is a hash with form params, with file param replaced with cached file data, which can later be assigned again to the record.

attacher.form_assign({ "image" => file, "title" => "...", "description" => "..." })
#=> { :image => '{"id":"...","storage":"...","metadata":"..."}', "title" => "...", "description" => "..." }

You can also have attached file data returned as the <name>_data attribute, suitable for persisting.

attacher.form_assign({ "image" => image, ... }, result: :attributes)
#=> { :image_data => '{"id":"...","storage":"...","metadata":"..."}', "title" => "...", "description" => "..." }