Versions Compared

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.


Page Properties


Submitted Date

  

Approved Date

 

Status

SUPERSEDED by ADR-xxx

ImpactMEDIUM


 

Overrides/Supersedes 

...

Rationale

Analysis and options

Basically, 2 main alternatives can be suggested for the provided context:

Alternative option

Brief description

Potential use cases

Cascade deletiondeleting a code-module record leads to all non-core-modules records referring to it must also be deleted
  • cascade deletion of outdated records
Soft deletiona core-module record is not being physically deleted but is being rather marked with a specific dedicated flag (e.g. is_deleted = true / false)
  • manual deletion made by end users

It looks that both options can be viable for FOLIO depending on particular use case.

It worth also noting that Image ModifiedUICR-125 - Data corruption. When holding/item data are moved in Inventory, then the item in Courses is not updated accordingly OPENcase is slightly different and is about dangling references while not deletion but moving of a core-module record; neither cascade nor soft deletion is applicable here. At the same time, this case and cascade deletion case have one great similarity - in both, non-core-modules are to be notified about a change in core-module. In this context, a robust notification channel with guaranteed delivery to transfer change events from one module (say, module-source) to another module (say, module-recipient) is required.  More details are on Data consistency and message driven approach # Notification channel.

Soft deletion option

More details regarding this option.

  • Q: It requires that every client understands that deleted records might be present and when the API will provide them and when it will not.
    • A: Sure, every client should know the rules of the game. Though once the rules will be agreed and shared, it's just a platform-wide knowledge
  • Q: Let's say a loan references an item, that item is then soft-deleted, when the loan is presented in the UI, would the item information be presented or not?
    • A: Yes, the loan is available, and the item information still can be retrieved by a single endpoint. At the same time, loan UI should be able to notify end user that the item has been deleted (via a warning message, or via a dedicated UI field, or via disabling of editing particular values received from the item

High level actions required for core / non-core modules are shown below:

Core module

Another module referencing core module

  • add an is_deleted flag to schema via Liquibase with false as a default value
  • Create - new records are to be created with is_deleted=false
  • Read
    • collection endpoint only returns not-deleted records
    • single endpoint can return both deleted and not-deleted records
  • Update - add a check for every update - update of a record with is_deleted=false is only allowed
  • Delete - implement soft-deletion with setting is_deleted to true
  • add an UI element showing if a record from code module is deleted or not, or disable editing of fields came from core module, or add a message to end user with the warning that a core module record this record is referencing to, is deleted

Decision

Yikes


Implications

...