How to query for distinct results in mongodb with python?

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I have a mongo collection with multiple documents, suppose the following (assume Tom had two teachers for History in 2012 for whatever reason)

{
"name" : "Tom"
"year" : 2012
"class" : "History"
"Teacher" : "Forester"
}

{
"name" : "Tom"
"year" : 2011
"class" : "Math"
"Teacher" : "Sumpra"
}


{
"name" : "Tom",
"year" : 2012,
"class" : "History",
"Teacher" : "Reiser"
}

I want to be able to query for all the distinct classes "Tom" has ever had, even though Tom has had multiple "History" classes with multiple teachers, I just want the query to get the minimal number of documents such that Tom is in all of them, and "History" shows up one time, as opposed to having a query result that contains multiple documents with "History" repeated.

I took a look at: http://mongoengine-odm.readthedocs.org/en/latest/guide/querying.html

and want to be able to try something like:

student_users = Students.objects(name = "Tom", class = "some way to say distinct?")

Though it does not appear to be documented. If this is not the syntactically correct way to do it, is this possible in mongoengine, or is there some way to accomplish with some other library like pymongo? Or do i have to query for all documents with Tom then do some post-processing to get to unique values? Syntax would be appreciated for any case.

mongoengine mongodb python
3 Answers
import pymongo
posts = pymongo.MongoClient('localhost', 27017)['db']['colection']


res = posts.find({ "geography": { "$regex": '/europe/', "$options": 'i'}}).distinct('geography')
print type(res)
res.sort()
for line in res:
    print line

refer to http://docs.mongodb.org/manual/reference/method/db.collection.distinct/ distinct returns a list , will be printed on print type(res) , you can sort a list with res.sort() , after that it will print the values of the sorted list.

Also you can query posts before select distinct values .

user_7785170
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