Query django foreignkey relationship - django

Question

I am developing an audit management information system where I can record all finding related to an audit. I have models with foreignkeys relationship. How do I see all findings with a particular assignment and audit_title and unit?
See relevant codes below.
model.py content
class Unit(models.Model):
unit_name = models.CharField(max_length=30, blank=True, null=True)
def __unicode__(self):
return self.unit_name
class Assignment(models.Model):
assignment_name = models.CharField(max_length=30, blank=True, null=True)
def __unicode__(self):
return self.assignment_name
class Task(models.Model):
task_title = models.CharField(max_length=35, blank=True, null=True)
return self.task_title
class Finding(models.Model):
assignment = models.ForeignKey(Assignment, blank=True, null=True)
audit_title = models.ForeignKey(Task, blank=True, null=True)
auditor = models.ManyToManyField(User, blank=True)
unit = models.ForeignKey(Unit, blank=True, null=True)
audit_period = models.DateField(auto_now_add=False, auto_now=False, blank=True, null=True)
contact_person = models.CharField('Contact Person', max_length=500, blank=True, null=True)
finding = models.TextField('Detail Finding', max_length=500, blank=True, null=True)
be = models.CharField(max_length=30, blank=True, null=True)
form.py
class FindingSearchForm(forms.ModelForm):
class Meta:
model = Finding
fields = ['assignment',
'audit_title',
'unit',
'be',
]
Am I have the following in my views.py but I have this error invalid literal for int() with base 10: ''
views.py content
def finding_list(request):
title = 'List of Finding'
queryset = Finding.objects.all()
queryset_count = queryset.count()
form = FindingSearchForm(request.POST or None)
context = {
"title": title,
"form": form,
"queryset_count": queryset_count,
}
if request.method == 'POST':
unit = form['unit'].value()
audit_title = form['audit_title'].value()
assignment = form['assignment'].value()
queryset = Finding.objects.all().order_by('-timestamp').filter(be__icontains=form['be'].value(),
unit_id=unit,
assignment_id=assignment,
audit_title_id=audit_title,)

Answer 1

if request.method == 'POST':
unit = form['unit'].value()
audit_title = form['audit_title'].value()
assignment = form['assignment'].value()
queryset = Finding.objects.all().order_by('-timestamp').filter(be__icontains=form['be'].value()
)
if (unit != ''):
queryset = queryset.filter(unit_id=unit)
if (audit_title != ''):
queryset = queryset.filter(audit_title_id=audit_title)
if (assignment != ''):
queryset = queryset.filter(assignment_id=assignment)