There are two models "Sensors" with information about them and
"Measurments" .
class Sensor(models.Model):
date_start = models.DateField()
Latitude = models.DecimalField(max_digits=18, decimal_places=15)
Longitude = models.DecimalField(max_digits=18, decimal_places=15)
def __str__(self):
return 'id:%s / %s' % (self.id, self.date_start)
class Measurment(models.Model):
sens = models.ForeignKey(Sensor, on_delete=models.PROTECT)
time_of_measurment = models.DateTimeField()
humidity = models.PositiveSmallIntegerField()
temperature1 = models.DecimalField(max_digits=5, decimal_places=2)
temperature2 = models.DecimalField(max_digits=5, decimal_places=2)
temperature3 = models.DecimalField(max_digits=5, decimal_places=2)
def __str__(self):
return 'sens_id:%s, time:%s' % (self.sens.id, self.time_of_measurment)
>From each sensor I serially recive measurments. On the page, it is
necessary to display the sensor data and the latest measurement data from
the "Measurments" model corresponding for each sensor.
for displaying data about sensor I used ListView:
view:
from .models import Sensor, Measurmentclass SenorsListView(generic.ListView):
model = Sensor, Measurment
context_object_name = 'sensors_list'
template_name = 'sensors_list.html'
queryset = Sensor.objects.all().order_by('-date_start')
template "sensors_list.html":
{% extends "base_generic.html" %}{% block content %}
<h1>Sensors List</h1>
{% if sensors_list %}
<table class="table">
<tr>
<td><h4>ID sens<h4></td>
<td><h4>Date of install<h4></td>
<td><h4>Latitude<h4></td>
<td><h4>Longitude<h4></td>
<td><h4>Data from last measurments<h4></td>
</tr>
{% for sensor in sensors_list %}
<tr>
<td>{{sensor.id}}</td>
<td>{{sensor.date_start}}</td>
<td>{{sensor.Latitude}}</td>
<td>{{sensor.Longitude}}</td>
<td>{{}}</td>
</tr>
{% endfor %}
</table>
{% else %}
<p>There are no sensors in the DB.</p>
{% endif %} {% endblock %}
But dont know How to display data about last measurments. I think need
using aggregate to calculate max of time_of_measurment for each id_sens.
How it can be done?
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