Using map() on a _set in a template?
- by Stuart Grimshaw
I have two models like this:
class KPI(models.Model):
"""KPI model to hold the basic info on a Key Performance Indicator"""
title = models.CharField(blank=False, max_length=100)
description = models.TextField(blank=True)
target = models.FloatField(blank=False, null=False)
group = models.ForeignKey(KpiGroup)
subGroup = models.ForeignKey(KpiSubGroup, null=True)
unit = models.TextField(blank=True)
owner = models.ForeignKey(User)
bt_measure = models.BooleanField(default=False)
class KpiHistory(models.Model):
"""A historical log of previous KPI values."""
kpi = models.ForeignKey(KPI)
measure = models.FloatField(blank=False, null=False)
kpi_date = models.DateField()
and I'm using RGraph to display the stats on internal wallboards, the handy thing is Python lists get output in a format that Javascript sees as an array, so by mapping all the values into a list like this:
def f(x): return float(x.measure)
stats = map(f, KpiHistory.objects.filter(kpi=1)
then in the template I can simply use
{{ stats }}
and the RGraph code sees it as an array which is exactly what I want.
[87.0, 87.5, 88.5, 90]
So my question is this, is there any way I can achieve the same effect using Django's _set functionality to keep the amount of data I'm passing into the template, up until now I've been passing in a single KPI object to be graphed but now I want to pass in a whole bunch so is there anything I can do with _set
{{ kpi.kpihistory_set }}
dumps the whole model out, but I just want the measure field.
I can't see any of the built in template methods that will let me pull out just the single field I want.
How have other people handled this situation?
