Store document diffs

[mingard]

Overview

On Top of the existing history collection, which is useful for auditing at DB level, introduce a diff collection to handle unpublished changes.

Features

• Store diff document in a separate collection
• Flag published state on each diff document
• Apply unpublished diffs based on ?includeDiffs=true flag on GET query
• Apply all diffs and save to original document with a single call to the document endpoint

Benefits

• Introduces a draft state to all documents
• Can be used in web for a preview instance
• Introduces a reliable changelog view
• Removes the need to retain all history

Questions for the floor

• How do we handle hooks? Do compile the diffs before handing to a hook if includeDiffs is present on POST and PUT?
• Can a PUT request be made to a document that has outstanding diffs

[mingard]

@abovebored @jimlambie and @josephdenne as discussed yesterday.

@eduardoboucas hooks question for you :)