如何删除django请求中的重复项

Question

删除Django查询中的重复项。我使用select_related并将请求数量从90个减少到18个，但是如果数据库增长，那么这并不能拯救我。如何改进查询?

views.py
def index(request):  
snj = ScheduleNotJob.objects.select_related()
form = SNJ()
return render(request,"index.html",{'snj': snj, 'form':form})  

models.py

class Office(models.Model):  
title = models.CharField(max_length=150, db_index=True)  
def __str__(self):
return self.title

class Post(models.Model):
office = models.ForeignKey(Office, on_delete=models.CASCADE)  
title = models.CharField(max_length=150, db_index=True)
def __str__(self):
return self.title

class Human(models.Model):  
office = models.ForeignKey(Office, on_delete=models.CASCADE)  
post = ChainedForeignKey(
Post, 
chained_field="office",
chained_model_field="office", 
show_all=False, 
)  
initials = models.CharField(max_length=150, db_index=True)  

def __str__(self):
return self.initials

class Reason(models.Model):  
title = models.CharField(max_length=150) 
def __str__(self):
return self.title

class Shift(models.Model):  
title = models.CharField(max_length=150) 
def __str__(self):
return self.title

class ScheduleNotJob(models.Model):
shift = models.ForeignKey(Shift, on_delete=models.CASCADE) 
office = models.ForeignKey(Office, on_delete=models.CASCADE) 
post = GroupedForeignKey(Post, "office") 
human = GroupedForeignKey(Human, "post") 
reason = models.ForeignKey(Reason, on_delete=models.CASCADE)
comment = models.CharField(max_length=300, blank=True, null=True)
length_time = models.IntegerField(blank=True, null=True)
date_start = models.DateField(blank=True, null=True) 
date_end = models.DateField(blank=True, null=True) 

index.html

{% for elem in snj %}  
<tr class="mySelect">  
<td>{{ elem.id }}</td>  
<td>{{ elem.shift }}</td> 
<td>{{ elem.office }}</td> 
<td>{{ elem.post }}</td> 
<td>{{ elem.human }}</td>  
<td>{{ elem.reason }}</td>  
<td>{{ elem.comment }}</td> 
{% endfor %}

我使用select_related并将请求数量从90个减少到18个，但是如果数据库增长，那么这将无法拯救我。如何改进查询?

Answer 1

您可以使用Only()方法并传递所需的字段，这些字段在计算查询集时立即加载。

def index(request):  
snj = ScheduleNotJob.objects.select_related(
'shift', 'office', 'post', 'human'
).only(
'id', 'reason', 'comment', 'shift_id', 'shift__title', 'office_id', 'office__title', 'post_id', 'post__title', 'human_id', 'human__initials'
)
form = SNJ()
return render(request,"index.html",{'snj': snj, 'form':form})

Answer 2

my_list = [1, 2, 3, 3, 4, 5, 5]
my_list = list(set(my_list))
print(my_list)  # prints [1, 2, 3, 4, 5]

如果你有一个包含重复项的列表或其他集合，你可以使用Python内置的set()函数来删除重复项。