Django Using Variable in Filter within For Loop

Question

I am trying to get the child object/field value using a parent object. The parent is a variable within a for loop and I can't seem to hand it into the custom tag.

#custom_tags.py
@register.simple_tag()
def assigned_to(sample):
    #sample=sample.pk
    return Lab_Request.objects.filter(sample=sample).first().lab.lab_name

@register.filter()
def assigned_too(sample):
    #sample=sample.pk
    return Lab_Request.objects.filter(sample=sample).first().lab.lab_name

#sample.html
{% for sample in samples %}

                {% static sample.0|assigned_too %}

                {% if user.profile.employee.pk == sample.inspector.employee.pk or perms.ics.view_sample %}

                                    <tr>
                                        <td class="column1">{{ sample.sample_date }}</td>
                                        <td class="column2">{{ sample.status|sample_status_options }}</td>
                                        <td class="column3"><a href="#">{{ sample.sample_number }}</a></td>
                                        <td class="column4"><a href="#">{{ sample.order.customer.customer_name }}</a></td>
                                        <td class="column5"><a href="#">{{ sample.lab_request.placeholder_to_be_replaced }}{{ sample.lab_request.lab.lab_name }}{{ sample.inspection_request.inspector.employee.employee_first_name }}</a></td>
                                        <td class="column6">{{ sample.date_modified|date:'M. d, Y'  }}</td>
                                    </tr>
                {% endif %}
            {% endfor %}

{% static sample|assigned_too %} is the part I am struggling with. I have also tried to write a function and call it like {% assigned_to {{ sample }} %}. It does work if I use {% static 1|assigned_too %} but then it doesn't iterate with my loop like it needs to. I'm not sure if I am doing this this most complicated way possible. I just want information from a child of the parent such as {{ sample.lab_request.lab.lab_name }} where sample is a parent object and lab_request is a child model.

EDIT:

#views.py
class SampleHomeView(ListView):
    model = Sample
    samples = Sample.objects.all
    context_object_name = 'samples'
    template_name = 'ics/sample.html'
    ordering = ['-sample_date']
    paginate_by = 10

#urls.py
path('sample/', SampleHomeView.as_view(), name='sample-home'),

#models.py

class Lab_Request(models.Model):
    #Add stuff here
    placeholder_to_be_replaced = models.CharField(max_length=1)
    lab = models.ForeignKey(Lab, on_delete=models.CASCADE, null=True, blank=True)
    sample = models.ForeignKey(Sample, on_delete=models.CASCADE)

class Sample(models.Model):

    order = models.ForeignKey(Order, on_delete=models.CASCADE)
    employee = models.ForeignKey(Employee, on_delete=models.CASCADE)
    status = models.CharField(max_length=2, choices=SAMPLE_STATUS_OPTIONS, default="01")

class Order(models.Model):

    order_number = models.CharField(max_length=19, unique=True, editable=False, default=get_order_number)
    status = models.CharField(max_length=2, choices=ORDER_STATUS_OPTIONS)
    specification = models.ForeignKey(Specification, on_delete=models.CASCADE, null=True, blank=True) #Needs work to determine which spec is appropriate
    customer = models.ForeignKey(Customer, on_delete=models.CASCADE)
    user = models.ForeignKey(User, on_delete=models.CASCADE)

class Lab(models.Model):

    status = models.CharField(max_length=2, choices=STATUS_OPTIONS)
    lab_name = models.TextField(max_length=100, unique=True)

Answer 1

OK I figured it out. I needed to call the child to the parent slightly differently than I was doing. I need to use {{ sample.lab_request_set.all.0.lab }} instead of the {{ sample.lab_request.lab }}

For anyone that needs this in the future, if you do not set a related name in the ForeignKey then it will be parent_model_name.child_model_name_set.all this will give you a query set that you can then iterate through or just select the first like I did with the .0 at the end of the .all. This works in a template. If you need it in a python file then you will be calling the function with parent_model_name.child_model_name_set.all()