from django.db import models


# Create your models here.


class SensorType(models.Model):
    name = models.CharField(max_length=30)
    unit = models.CharField(max_length=10)

    def __str__(self):
        return self.name


class Sensor(models.Model):
    sensor_type = models.ForeignKey(SensorType, on_delete=models.CASCADE)
    name = models.CharField(max_length=30)

    def __str__(self):
        return self.name


class Measurement(models.Model):
    sensor_id = models.ForeignKey(Sensor, on_delete=models.CASCADE)
    value = models.FloatField()
    timestamp = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return "{} {} {} {}".format(self.sensor_id, self.value, self.sensor_id.sensor_type.unit, self.timestamp)