Django model get unique foreign key rows based on other column max value -

i'm new django, , i'm trying create simple application keep track on different server configurations in sqlite database. i've created 2 database models:

from django.db import models  class server(models.model):     name = models.charfield(max_length=250)  class config(models.model):     server = models.foreignkey(server, on_delete=models.cascade)     configuration = models.charfield(max_length=250)     config_version = models.integerfield() 

here 2 models sample data:

server: | id     | name    | | ------ | ------  | | 1      | server1 | | 2      | server2 | | 3      | server3 |  config: | id     | configuration | config_version | server | | ------ | ------------- | -------------- | ------ | | 1      | srv1_cfg1     | 1              | 1      | | 2      | srv2_cfg1     | 1              | 2      | | 3      | srv2_cfg2     | 2              | 2      | | 4      | srv2_cfg3     | 3              | 2      | | 5      | srv3_cfg1     | 1              | 3      | | 6      | srv1_cfg2     | 2              | 1      | | 7      | srv1_cfg3     | 3              | 1      | 

i query config table, , rows maximum value of "config_version" field each server id, like:

desired result: | id     | configuration | config_version | serverid | servername | | ------ | ------------- | -------------- | -------- | ---------- | | 4      | srv2_cfg3     | 3              | 2        | server2    | | 5      | srv3_cfg1     | 1              | 3        | server3    | | 7      | srv1_cfg3     | 3              | 1        | server1    | 

i've tried many different options construct correct query, far cannot want. best result query server table:

server.objects.annotate(maxver=max('config__config_version')) 

but seems cannot access config table objects, guess need query config table filtering?

i can raw sql query, prefer "django" way. appreciated.

after more struggle this, i've came solution works me. i'm sure not optimal, @ least seems works:

from django.db.models import max, f  s1 = config.objects.annotate(maxver=max('server__config__config_version')) config_list = s1.filter(config_version=f('maxver')) 

if there better way this, love know it.