python - 将具有多个循环和逻辑的代码简化为查询集聚合

Question

我的模型:

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)

我的目标:为查询过滤器设置一个变量，向查询集添加一个属性“is_admitted”，以便我可以将此查询集传递给模板并在显示数据时使用该属性。

代码:

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)

在模板中，我会做:

{% for cust, status in cust_templ_set %}
    {{ cust.name }} {{ status }}
{% endfor %}

我想了解如何通过在查询集上生成聚合来转换上述代码，以便我可以使用查询的属性，并将模板代码更改为以下内容，并避免 View 中的循环，和 zipper 。这样模板代码就变成了:

{% for cust in customers %}
    {{ cust.name }} {{ cust.is_admitted }}
{% endfor %}   

我不确定我是否完全有道理，可以进一步解释。

Answer 1

我不确定我是否理解正确，也许您可​​能想要这个:

cust = customer.objects.filter(my_q, linkedclinic=clinicobj)
is_admitted_sub_q = Admission.objects.filter(customer=OuterRef('pk'), discharged=False)
cust_templ_set = cust.annotate(is_admitted=Exists(is_admitted_sub_q), )

如果在 Admission 中存在至少一个链接(到此客户)记录，这将返回一个包含附加字段 is_admitted 的客户列表，该字段将为 True 。

OuterRef , Exists