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Given mongo document like below, how to efficiently find all documents and return student_id field as integer?

 {
     "_id" : ObjectId("58dd757910d81946b8ff853a"),
     "student_id": "4169506398",
     "first_name": "steven",
     "last_name": "smith",
     "date_of_birth": "02-07-1988"
}
{
     "_id" : ObjectId("58dd757910d81946b8ff853b"),
     "student_id": "6902",
     "first_name": "michael",
     "last_name": "clarke",
     "date_of_birth": "05-30-1988"
}

Expected result (in Json):

{
     "student_id": 4169506398
}
{
     "student_id": 6902
}

I've 29000 records. Getting documents using db.find({}) and casting student_id to integer when looping might have performance issue.

styvane
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Sheshank Kodam
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1 Answers1

1

You can't do this without client side processing or map reduce.

mylist = map(int, db.collection.distinct('student_id'))

which yields a list of student_id of type int in PY2 or iterator object in PY3

You can also use the .aggregate() method as shown here if "student_id" is not unique within the collection and you don't want to de-duplicate the result.

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styvane
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