How to extract last objectID of mongoDB document in Python?

Question

I want to extract last objectID of a document from a collection in python and want to store it in python object.

I am doing something like this

db.dataset2.find().sort( {'_id': -1 } ).limit(1);

But it gives me an error.

TypeError: if no direction is specified, key_or_list must be an instance of the list

Please help.

Sede · Accepted Answer · 2015-12-05 10:44:47Z

5

You are doing it wrong. The .sort takes a key or list and optional direction as arguments.

db.dataset2.find().sort('_id', pymongo.DESCENDING).limit(1)[0]['_id'];

or

db.dataset2.find().sort('_id', -1).limit(1)[0]['_id'];

edited Dec 5, 2015 at 10:44

answered Dec 5, 2015 at 10:41

Sede

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1 Comment

Mohamed Reda Over a year ago

Thanks, your second line of code worked fine for me.

Andrei S. Klimanov · Accepted Answer · 2021-06-02 00:58:42Z

1

cursor = mycol.find().sort('_id', -1).limit(1)
for document in cursor:
    print(document)

answered Jun 2, 2021 at 0:58

Andrei S. Klimanov

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1 Comment

Yunnosch Over a year ago

While this code may solve the question, including an explanation of how and why this solves the problem would really help to improve the quality of your post, and probably result in more up-votes. Remember that you are answering the question for readers in the future, not just the person asking now. Please edit your answer to add explanations and give an indication of what limitations and assumptions apply.

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