我可以只获取 Cursor 对象（pymongo）中的第一项吗？

Question

so I created a Cursor object by having

cdb=self.mongo['bleh_bleh_bleh_setup_here']
data=cdb[collection].find(query_commands_here)

Don't worry about the syntax above. Just assume that I can successfully create such cursor object

I know I can do a for loop to iterate through the object, but all I want is the very first item of this object. Is there a more efficient way than looping through?

EDIT:

to make things more clear, the 'bleh_bleh_bleh_setup_here' is simply path to connect to the desired mongoDB, and 'query_commands_here' are queries like {field1:{'$gt':num1}, field2:{'$ne':num2}} that sort of things. The line

data=cdb[collection].find(query_commands_here)

will give me a Cursor object that I can iterate with a for loop. So things like

for item in data:
    print item

will print out each of the entry in the object. It works nicely. However, according to the documentation, this cursor object should have method called .hasNext() , which should return True if there's a next entry. So far, I haven't found a way to get it to work for some odd reason. data.next() does give me an entry though. I want to make sure I can have that condition to make sure I don't call .next() for a cursor object that contains nothing, though I don't foresee this kind of situation happening, but I would assume it'd occur at some point.

Answer 1

.find_one() would return you a single document matching the criteria:

cdb[collection].find_one(query_commands_here)

---

Note that the PyMongo Cursor does not have a hasNext() method. What I would do is to call cursor.next() and handle the StopIteration exception:

try:
    record = cursor.next()
except StopIteration:
    print("Empty cursor!")

Answer 2

You can also do the following (without having to handle the StopIteration exception) :

cur = cdb[collection].find(query_commands_here)
record = next(cur, None)
if record:
    # Do your thing

This works because python's built in next() will return the default value when it hits the end of the iterator.