How to return NULL and not an Exception with Pymongo

Question

If I pass an invalid row, it throws an exception. I would like it to return NULL so I can use it to further process the rest of my scripts.

module_id = module_id

mongo_document = mongo_collection.find_one({ '_id': '%s' % module_id}, { '_id':0, 'svn_path':1 })
myvar = mongo_document
for key, value in myvar.iteritems():
    print value

Which exception is actually being raised? it looks like find_one might return None already if no matching collections are found. github.com/mongodb/mongo-python-driver/blob/master/pymongo/…, is myvar None? and you are trying to call iteritems on None? — dm03514
– dm03514, Commented Jul 23, 2013 at 17:14
I'm an idiot, you're right it does return none. I didnt check for this, I went ahead and attempted to print the value without checking. — sdot257
– sdot257, Commented Jul 23, 2013 at 17:17

0xdead · Accepted Answer · 2013-07-23 17:17:48Z

1

Actually your problem isn't in the find_one function. when you ask for a value that doesnt exist its returns a None value to python, my guess that your exception is actually in the for loop. so i would do something like that:

module_id = module_id

mongo_document = mongo_collection.find_one({ '_id': '%s' % module_id}, { '_id':0, 'svn_path':1 })
myvar = mongo_document
if myvar is not None:
   for key, value in myvar.iteritems():
       print value
eilf:
   print "sorry i could find that id"

answered Jul 23, 2013 at 17:17

0xdead

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2 Comments

sdot257 Over a year ago

yea that was it, I forgot to check myvar

sdot257 Over a year ago

Yep, i have to wait a few more mins.

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