The problem

You want to find all the ActiveRecord models that either do / do not have a record attached to them.

The solution

Let's say you have aPost class which has one image attached like so:

classPost<ApplicationRecordhas_one_attached:imageend

To query for allPosts that do not have an image attached the syntax would look like this:

Post.left_joins(:image_attachment).where(active_storage_attachments:{id:nil})

This will return all posts that do not have an image. If you want to find all posts thathave an image attached, you would use a#not clause in there like so:

Post.left_joins(:image_attachment).where.not(active_storage_attachments:{id:nil})

has_many_attached

This can even be extended tohas_many_attached by using the plural form of:image_attachment like so:

classPost<ApplicationRecordhas_many_attached:imagesend# Query for all without attachmentsPost.left_joins(:image_attachments).where(active_storage_attachments:{id:nil})# Query for all with attachmentsPost.left_joins(:image_attachments).where.not(active_storage_attachments:{id:nil})

Final Syntax

The syntax for attachments is fairly straightforward like so:

ModelName.left_joins(:<attachment_name>_attachment[s]).where(active_storage_attachments:{<column>:<value>})

And thats it! Good luck and enjoy your new found query power!