Attachments associate records with blobs. Usually that’s a one record-many blobs relationship, but it is possible to associate many different records with the same blob. A foreign-key constraint on the attachments table prevents blobs from being purged if they’re still attached to any records.

Attachments also have access to all methods from ActiveStorage::Blob.

If you wish to preload attachments or blobs, you can use these scopes:

# preloads attachments, their corresponding blobs, and variant records (if using `ActiveStorage.track_variants`)
User.all.with_attached_avatars

# preloads blobs and variant records (if using `ActiveStorage.track_variants`)
User.first.avatars.with_all_variant_records

Methods

Instance Public methods

purge()

Synchronously deletes the attachment and purges the blob.

📝 Source code 
# File activestorage/app/models/active_storage/attachment.rb, line 33
  def purge
    transaction do
      delete
      record.touch if record&.persisted?
    end
    blob&.purge
  end
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purge_later()

Deletes the attachment and enqueues a background job to purge the blob.

📝 Source code 
# File activestorage/app/models/active_storage/attachment.rb, line 42
  def purge_later
    transaction do
      delete
      record.touch if record&.persisted?
    end
    blob&.purge_later
  end
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variant(transformations)

Returns an ActiveStorage::Variant or ActiveStorage::VariantWithRecord instance for the attachment with the set of transformations provided. See ActiveStorage::Blob::Representable#variant for more information.

Raises an ArgumentError if transformations is a Symbol which is an unknown pre-defined variant of the attachment.

📝 Source code 
# File activestorage/app/models/active_storage/attachment.rb, line 56
  def variant(transformations)
    case transformations
    when Symbol
      variant_name = transformations
      transformations = variants.fetch(variant_name) do
        record_model_name = record.to_model.model_name.name
        raise ArgumentError, "Cannot find variant :#{variant_name} for #{record_model_name}##{name}"
      end
    end

    blob.variant(transformations)
  end
🔎 See on GitHub