A further bit of clarification
clusters = nodes.values('cluster').annotate(count_left=min(F(
'cluster__volume_limit') - F('cluster__volume_count'),
Sum(F(
'volume_limit') - F('volume_count'))),
size_left=min(F(
'cluster__size_limit') - F('cluster__volume_size'),
Sum(F('size_limit')
- F('volume_size'))))
produced duplicate entries as
<QuerySet [{'cluster': 1, 'size_left': 1960, 'count_left': 18}, {'cluster':
1, 'size_left': 1960, 'count_left': 18}, {'cluster': 2, 'size_left': 2000,
'count_left': 20}, {'cluster': 2, 'size_left': 2000, 'count_left': 20}]>
Using distinct() remove duplicates as follows
clusters = nodes.values('cluster').annotate(count_left=min(F(
'cluster__volume_limit') - F('cluster__volume_count'),
Sum(F(
'volume_limit') - F('volume_count'))),
size_left=min(F(
'cluster__size_limit') - F('cluster__volume_size'),
Sum(F('size_limit')
- F('volume_size')))).distinct()
<QuerySet [{'cluster': 1, 'size_left': 1960, 'count_left': 18}, {'cluster':
2, 'size_left': 2000, 'count_left': 20}]>
But am not sure If that I am doing this appropriately.
Sarvi
On Saturday, July 1, 2017 at 5:59:41 PM UTC-7, sarvi wrote:
>
> This seems to work
> Node.objects.values('cluster').annotate(volume_left=min(F('cluster__volume_limit')-F('cluster__volume_count'),
>
> Sum(F('volume_limit')-F('volume_count'))))
>
> <QuerySet [{'cluster': 1, 'volume_left': 8}, {'cluster': 1, 'volume_left':
> 8}, {'cluster': 2, 'volume_left': 20}, {'cluster': 2, 'volume_left': 20}]>
>
>
> Do I have it right? Just wanted to confirm.
>
> Thanks
>
>
> On Saturday, July 1, 2017 at 5:41:20 PM UTC-7, sarvi wrote:
>>
>>
>> Django Verion: 1.11.1
>>
>> My models
>>
>> class Cluster(models.Model):
>>
>> ....
>>
>> volume_limit = models.IntegerField('Cluster Volume Count Limit')
>>
>> volume_count = models.IntegerField('Cluster Volume Count', default=0)
>>
>> ....
>>
>>
>> class Node(models.Model):
>>
>> cluster = models.ForeignKey(Cluster, related_name='cluster_nodes',
>> on_delete=models.PROTECT)
>>
>> volume_limit = models.IntegerField('Node Volume Count Limit')
>>
>> volume_count = models.IntegerField('Node Volume Count', default=0)
>>
>>
>> My query
>>
>> nodes = Node.objects.filter(....)
>>
>> intermediatestep =
>> nodes.objects.annotate(volume_left=F('volume_limit')-F('volume_count')).values('cluster__id').annotate(cluster_volume_left_sum=
>> Sum('volume_left'))
>>
>>
>> Error:
>>
>> File
>> "/Users/sarvi/virtenv/toothless/lib/python2.7/site-packages/django/db/models/expressions.py",
>>
>> line 471, in resolve_expression
>>
>> return query.resolve_ref(self.name, allow_joins, reuse, summarize)
>>
>> File
>> "/Users/sarvi/virtenv/toothless/lib/python2.7/site-packages/django/db/models/sql/query.py",
>>
>> line 1481, in resolve_ref
>>
>> return Ref(name, self.annotation_select[name])
>>
>> KeyError: 'volume_left'
>>
>>
>> My ultimate Goal:
>>
>> What I am trying to achieve is to get from a
>>
>> 1. filtered query of Nodes, to calculate
>> volume_left=F('volume_limit')-F('volume_count') for each node
>>
>> 2. then group by cluster and sum up what volume_left in each node to
>> cluster_volume_left_sum for each cluster.
>>
>> 3. Then get a cluster level
>> cluster_volume_left=F('volume_limit')-F('volume_count'),
>>
>> 4. Then calculate at the cluster level Min(0,
>> F('cluster_volume_left')-F('volume_left__sum'))
>>
>>
>> I am obviously stuck way earlier :-)
>>
>>
>> From what I read of the documentation and Stackoverflow this should be
>> possible
>>
>>
>> Any pointer on what I am doing wrong here would be of great help.
>>
>>
>> Thanks,
>>
>> Sarvi
>>
>
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