Opened 12 hours ago
Last modified 12 hours ago
#36718 assigned New feature
Enable JSON negative indexing for Oracle 21c+ using [last-N]
| Reported by: | Clifford Gama | Owned by: | Clifford Gama |
|---|---|---|---|
| Component: | Database layer (models, ORM) | Version: | dev |
| Severity: | Normal | Keywords: | JSONField array negative indexing |
| Cc: | Triage Stage: | Unreviewed | |
| Has patch: | yes | Needs documentation: | no |
| Needs tests: | no | Patch needs improvement: | no |
| Easy pickings: | no | UI/UX: | no |
Description
Follow up to #36085 which added negative indexing for sqlite (as a new feature for 6.0).
While doing some reading on JSON queries on Oracle, I found that you can index elements from the right by using [last-N].
An array index can also have the form last - N, where - is a minus sign (hyphen) and N is a literal whole number (0, 1, 2,…) that is no greater than the array size minus 1. The next-to-last array element can be referenced using index last-1, the second-to-last by index last-2, and so on. Whitespace surrounding the minus sign (hyphen) is ignored.
I think we can use this to support negative indexing on Oracle versions that support [last-N]. Currently, trying to do so raises a NotSupportedError per #36085 which was focused on sqlite.
I can't find Oracle release notes specifying when [last-N] indexing was added, but the note I quoted is only available in 21c+ docs.