Its not clear how you differentiate one measure as speed or another as
dir. Assuming only one has a link to another measure then you could
do something like:
results = Measurand.objects.exclude(entry__isnull=True).select_related
()
for speed in results:
speed_avg = speed.avg_value
dir_avg = speed.entry.avg_value
This first selects all measurements, excludes those that don't have a
link to another measurement, then fetches information about the
related measurements into the queryset.
-Preston
On Nov 17, 2:33 pm, tom <toab...@googlemail.com> wrote:
> Hi,
>
> i want to have the same model-field 2x in the query result.
>
> The model.py is:
> class Measurand(models.Model):
> """
> A Model for measurement data
> """
> entry = models.ForeignKey(Entry)
> avg_value = models.FloatField(help_text='the average measurement
> value', db_index=True, blank=True, null=True)
> def __unicode__(self):
> return 'Measurand:' + str(self.avg_value)
>
> My raw-sql looks like:
> cursor = connection.cursor()
> cursor.execute(""" SELECT speed.avg_value, dir.avg_value
> FROM data_measurand AS speed LEFT JOIN
> data_measurand AS dir
> ON speed.entry_id=dir.entry_id;
> """, locals() )
> row = cursor.fetchall()
>
> How can i do this with the django-orm?
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