Django Query data optimization - python-3.x

Question

Recently, I watched Django and discovered the teaching videos of select_related and prefetch_related.
So I installed debug_toolbar and took a look at my website
I searched the database too many times on one page.
I must convert it to json and send it back to the front end
Can I still optimize?
Is this the only way to go?
Below is my model .
models.py
def get_upload_path(instance, filename):
return f'register/{instance.owner.job_number}/{filename}'
def image_upload_path(instance, filename):
date = datetime.datetime.strptime(instance.date, '%Y-%m-%d %H:%M:%S')
return f'image/{date.year}/{date.month}/{date.day}/{filename}'
class UserProfile(models.Model):
name = models.CharField(max_length=64)
department = models.CharField(max_length=32)
job_number = models.CharField(max_length=32, unique=True)
card_number = models.CharField(max_length=32, unique=True)
location = models.CharField(max_length=32)
date = models.DateTimeField()
class UserRegister(models.Model):
owner = models.ForeignKey(UserProfile, on_delete=models.CASCADE)
date = models.DateTimeField()
feature = ArrayField(models.FloatField(null=True, blank=True), null=True, blank=True, size=512)
image = models.ImageField(upload_to=get_upload_path)
class Meta:
db_table = 'UserRegister'
class UserImage(models.Model):
owner = models.ForeignKey(UserProfile, on_delete=models.CASCADE)
heat = models.CharField(max_length=8, blank=True, null=True)
date = models.DateTimeField()
image = models.ImageField(upload_to=image_upload_path)
punch_in = models.CharField(max_length=8, blank=True, null=True)
class Meta:
db_table = 'UserImage'
views.py
def get_db_data(db, page, limit, model):
data = []
paginator = Paginator(db, limit)
try:
page_object = paginator.page(page)
all_page = paginator.num_pages
for db_data in page_object:
images = []
for image in db_data.userregister_set.all():
try:
url = f'/static/uploads{image.image.url}'
except ValueError:
url = '/static/imgs/assets/none.jpg'
images.append({'id': image.id, 'url': url})
_ = {
'id': db_data.id,
'name': db_data.name,
'department': db_data.department,
'job_number': db_data.job_number,
'card_number': db_data.card_number,
'location': db_data.location,
'date': db_data.date.strftime('%Y-%m-%d %H:%M:%S'),
'images': images,
}
data.append(_)
result = {
'data': data,
'all_page': all_page,
'page': int(page)
}
return result
except EmptyPage as error:
# 該頁數沒資料。
return {'msg': 'Error'}
class Test(Views):
def get(self, request):
name = request.GET.get('name')
department = request.GET.get('department')
job_number = request.GET.get('job_number')
card_number = request.GET.get('card_number')
location = request.GET.get('location')
start_date = request.GET.get('start_date')
end_date = request.GET.get('end_date')
order = request.GET.get('order', default='DESC')
page = request.GET.get('page', default=1)
limit = request.GET.get('limit', default=25)
user_profile = UserProfile.objects.all().select_related()
if name:
user_profile = user_profile.filter(name=name)
if department:
user_profile = user_profile.filter(department=department_table.department)
if job_number:
user_profile = user_profile.filter(job_number=job_number)
if card_number:
user_profile = user_profile.filter(card_number=card_number)
if location:
user_profile = user_profile.filter(location=locations_table.location)
if start_date and end_date:
user_profile = user_profile.filter(date__range=[start_date, end_date])
if order == 'DESC':
data = get_db_data(db=user_profile.order_by('-date'), page=page, limit=limit, model='api')
else:
data = get_db_data(db=user_profile.order_by('date'), page=page, limit=limit, model='api')
response = JsonResponse(data)
# return response # This is the response I want to return, but now I need to use `debug_toolbar`, so I return an empty page to facilitate my reading `debug_toolbar`.
return render(request, 'User/test1.html')
return JsonResponse(data) is what I want to return, but now I need to use debug_toolbar, so I return to an empty page to facilitate reading debug_toolbar.

Answer 1

Use select_related() or prefetch_related().
Put the associated parameters into.
can speed up the ORM.