How do I write a django ORM to fetch the most recent records from the table for a specific id.
Example:
I have table(tr_data) data like:
| id | trs(foreign key) | status | last_updated |
|---|---|---|---|
| 1 | 301 | 3 | 2022-11-28 06:14:28 |
| 2 | 301 | 4 | 2022-11-28 06:15:28 |
| 3 | 302 | 3 | 2022-11-28 06:14:28 |
| 4 | 302 | 4 | 2022-11-28 06:15:28 |
| 5 | 302 | 2 | 2022-11-28 06:16:28 |
I want to have a queryset values that gives me trs id with its latest status.I have tried with aggragate and MAX but not getting the desired result.
Expecting ouput as :
[{"trs":301, "status":4},"trs":302,"status":2}]
CodePudding user response：
Possible duplicate Django ORM: Group by and Max
You can achieve this by annotate and Max. In the tr_data model, add a related_name parameter to trs something like 'tr_status'.
Write an orm:
latest_objs = TrData.objects.annotate(temp=Max('trs__tr_status__last_updated')).filter(last_updated).values('trs', 'status')