用空字典进行设置在Python中返回False

Question

If someone doesn't fill out any forms in my Django formset, it returns [{}] .

How can I test whether this dictionary within a set has been populated or not? Something like the following, though this doesn't work as the empty dictionary seems to make the list return True:

form_output_when_empty = [{}]
if form_output_when_empty:
    print "This should not print"
    # currently this prints out, which is not what I want!
else:
    print "This should print."

form_output_when_filled = [{'name': 'John'}]
if form_output_when_filled:
    print "This should print"
else:
    print "This should not print"

Answer 1

In Python an empty dictionary or an empty list are "false", but a list containing and empty dictionary is instead "true".

To do the check that you want therefore you need to enter the list and check the element:

 if form and form[0]:
    ...

this will enter the if body only if the list has at least one dictionary and the first dictionary is not empty