Django模型过滤

Question

I have the following:

def foo(self):
    print "Test"
    scores = BasicScore.objects.filter(event__id=self.id).order_by('score_date')[0:1]
    print scores
    #return s
    #return Score.objects.all().order_by('start_date')[:1]
    return scores

And in my Template:

event.foo.0.value

This will work fine and I will be able to use BasicScore class.

However previously I had: return scores[0]

But I got this in the logs:

Test

[]

And the exception:

Exception Type: IndexError
Exception Value:    

list index out of range

Exception Location: /Library/Python/2.7/site-packages/django/db/models/query.py in __getitem__, line 207
Python Executable:  /usr/bin/python

I'm a little new to Django/Python, but why would the list of one return successfully, but accessing [0] end up erroring with accessing an empty set?

Answer 1

list []不是一个1的列表，它是一个0的列表，并且scores[0]应该引发IndexError 。