Simplifying code with multiple loops and logic, into queryset aggregates

[Joel Mathew]

My models:

class customer(models.Model):

cstid = models.AutoField(primary_key=True, unique=True)

insurance_number = models.CharField(max_length=100, blank=True, null=True)

name = models.CharField(max_length=35)

ageyrs = models.IntegerField(blank=True)

class Admission(models.Model):

id = models.AutoField(primary_key=True, unique=True)

clinic = models.ForeignKey(Clinic, on_delete=models.CASCADE)

customer = models.ForeignKey(customer, on_delete=models.CASCADE)

diagnosis = models.CharField(max_length=2000, default='', blank=True)

date_admission = models.DateTimeField(default=timezone.now)

ward = models.ForeignKey(Ward, on_delete=models.CASCADE)

bed = models.ForeignKey(Bed, on_delete=models.CASCADE)

discharged = models.BooleanField(default=False)

ip_number = models.IntegerField(blank=True)

ip_prefix = models.CharField(max_length=20, default='', blank=True)

My objective: Set a variable to a query filter, adding a property, 'is_admitted' to the queryset, so that I can pass this query set to the template and use the property while displaying data.

Code:

def is_admitted(cust):

admission = Admission.objects.filter(customer=cust, discharged=False)

admission_results = len(admission)

if admission_results > 0:

return True

return False

my_q = or_q_if_truthfull(

cstid=HospitalID,

name__lower__contains=name.lower() if name else None,

ageyrs=ageyrs if ageyrs.isdigit() else None,

agemnths=agemnths if agemnths.isdigit() else None,

mobile__contains=mobile if mobile else None,

alternate__contains=alternate if alternate else None,

email__lower__contains=email.lower() if email else None,

address__lower__contains=address.lower() if address else None,

city__lower__contains=city.lower() if city else None

)

ORSearchResult = customer.objects.filter(my_q, linkedclinic=clinicobj)

cust_set = []

cust_admission_status = []

for cust in ORSearchResult:

cust_set.append(cust)

cust_admission_status.append(is_admitted(cust))

print(f"Customer name: {cust.name} Admission status: {is_admitted(cust)}")

cust_templ_set = zip(cust_set, cust_admission_status)

And in template, I will do:

{% for cust, status in cust_templ_set %}

{{ cust.name }} {{ status }}

{% endfor %}

I want to understand how I can convert my above code by generating an aggregate over the queryset, so that I can use a property of the query, and change the template code to the following, and avoid the loop in the view, and the zip. So that the template code becomes:

{% for cust in customers %}

{{ cust.name }} {{ cust.status }}

{% endfor %}

I am not sure whether I am making complete sense, and can explain further.

Sincerely yours,

 Joel G Mathew

[Matthew Pava]

It was a little difficult to follow your message because the formatting is non-standard, but I think this might be what you’re looking for.

Also, you should try to follow more Python coding conventions: models start with an upper case letter. Variables start with a lower case letter.

 

And you probably want to use a QuerySet Manager on Customer. Maybe a query like this:

Customer.objects.annotate(is_admitted=Case(When(admission_set__discharged=False, then=True), default=False).distinct()

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[Joel Mathew]

Thank you Matthew. Excellent advise as always. When I started off with this project 5 months ago, I was a beginner to both django and python. I've come a bit along the journey. That customer model is the first model I created, and I was unaware of these conventions. By the time I realized that, the project has branched into several apps, and the code now runs into thousands of lines of code. I didnt change the naming due to fear of breaking other code. :)

Nowadays I do it more "pythonically". Still, it's great to have people like you offer excellent general advise to help budding enthusiasts!

Sincerely yours,

 Joel G Mathew

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