Writing a django ORM query

Question

I'm new to both django and python. I'm trying to figure out the best (most performant) way to do a query.

Here is my models:

class Immunization(models.Model):
    name = models.CharField(max_length=12, primary_key=True)
    verbose_name = models.CharField(max_length=80)
    desc = models.CharField(max_length=800)
    effective_duration = TimedeltaField()
    def __unicode__(self):
        return self.name

class Patient(models.Model):
    name = models.CharField(max_length=64)
    age = models.IntegerField()
    birthday = models.DateField()
    def __unicode__(self):
        return self.name

'''
    ImmunizationRecord is a specific date an immunization was administered to a given patient.
'''
class ImmunizationRecord(models.Model):
    patient = models.ForeignKey('Patient')
    immunization = models.ForeignKey('Immunization')
    date_administered = models.DateTimeField(auto_now_add=True)

The query I am trying to perform is:

* Get all Immunizations that a patient hasn't received in the past Immunizations.effective_duration.*

So far I am doing something like this:

def get_context_data(self, **kwargs):
    context = super(ProfileView, self).get_context_data(**kwargs)

    all = Immunization.objects.all()
    done = ImmunizationRecord.objects.filter(patient__name=self.request.user)

    for r in done:
        #TODO: add date check for expiry
        all = [s for s in all if r.immunization.name != s.name] 

    context['available_list'] = all
    return context

Answer 1

Something like this might improve things a bit.

Import numpy
Import datetime 
recent_immunizations = ImmunizationRecord.objects.filter(patient=request.user).order_by(date_administered).reverse()


output = []
for r in recent_immunization:
   if (datetime.datetime.today() - r.date_administered) > r.immunizations.effective_duration:
       output.append(r.immunization.name)

Waring this code is not tested!

Answer 2

Get all Immunizations that a patient hasn't received in the past Immunizations.effective_duration .

All vaccinations the patient NEEDS. So if they got the vaccination 20 days ago, and the effective_duration = 19, then they are 1 day overdue and they NEED the vaccination.

We need to get a patient; and then whatever immunization they have received. Then we need to know what is the difference in days from today and the date each immunization was administered; if that difference is less than the effective days; the patient needs that immunization again.

import datetime

today = datetime.datetime.today()

p = Patient.objects.get(pk=1) # Get some patient
imm = ImmunizationRecord.objects.filter(patient=p) # This patient's record

still_needed = []

for record in imm:
   # How many days have passed since the immunization was administered?
   days_since = (today - record.date_administered).days

   if record.immunization.effective_duration < days_since:
      still_needed.append(record.immunization)