CODEWITHSUNDEEP
djangodjango-orm
masonjarre
masonjarre

Reputation: 891

Django: Getting the most recent distinct objects

Supposing I have a WeatherReport object with fields date, temperature, and city.

I want to get all the most recent WeatherReport objects for each city. I think I would do something like

WeatherReport.objects.order_by('-date').distinct('city')

But this fails, returning the error

ProgrammingError: SELECT DISTINCT ON expressions must match initial ORDER BY expressions

Upvotes: 2

Views: 1632

Answers (1)

user3133084
user3133084

Reputation:

This should work. It worked with me when I came across this problem.

WeatherReport.objects.order_by('city', '-date').distinct('city')

It seems that the DISTINCT ON expression(s) must match the leftmost ORDER BY expression(s). So by making the column you use in distinct as the first column in the order_by, I think it should work.

Upvotes: 8

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