Re: Weird date math bug?

On 1 September 2017 at 16:13, Melvyn Sopacua <m.r.sopacua@gmail.com> wrote:

A few tips on your code:

    def get_latest_chemo(self):
        chemo = ChemoRegime.objects.filter(patient=self).latest('stop_date')

    class ChemoRegime(models.Model):
        patient = models.ForeignKey(Patient, on_delete=models.CASCADE)

Use the related manager here. To make it readable, use:

    class ChemoRegime(models.Model):
        patient = models.ForeignKey(Patient, on_delete=models.CASCADE,
related_name='chemo_regimes')

    class Patient(models.Model):
        def get_latest_chemo(self):
            return self.chemo_regimes.latest('stop_date')

When providing properties for use in templates, make them properties -
makes the template more readable:

    @property
    def latest_chemo(self):
         return self.chemo_regimes.latest('stop_date')

    {{ patient.latest_chemo }}

Similarly you can abstract active regimes:

    class ChemoRegime(models.Model):
         @property
         def is_active(self):
              return self.stop_date is None

    {% if chemo.is_active %}<span class="badge
badge-primary">Current</span>{% endif %}


Of course, latest_chemo, should really be this if
active and non-active regimes can be mixed:

    @property
    def has_active_chemo(self):
         return self.chemo_regimes.filter(stop_date__isnull=True).count() > 0

    @property
    def latest_chemo(self):
         if not self.chemo_regimes.count():
              return None
         if self.has_active_chemo:
              return self.chemo_regimes.latest('start_date')
         return self.chemo_regimes.latest('stop_date')

Hope this helps :)

Melvyn - have only just got around to implementing your suggestions. Excellent, worked a treat. Thank you for the new tricks!

Cheers

L.

 

------
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