How to run mongodb queries in python

Question

I am using below query to get data from the collection in mongodb

db.testcoll.aggregate([
  { $unwind :'$data'},
  { $match : {'type': 'data1', "my_id" : "44ef", 'data.time': { $gte : "2018-07-07 00:00:30" , $lte : "2018-07-08 00:57:30"} }},
  { $project : { _id:0, my_id: '$my_id', time : '$data.time', value : '$data.value'} }
])

Running the above query in MongoDb, I get appropriate results. Now I am writing a small python script where I need to run the same query.

query = ([
  { '$unwind' :'$data'},
  { '$match' : {'type': 'data1', "my_id" : "44ef", 'data.time': { '$gte' : "2018-07-07 00:00:30" , '$lte' : "2018-07-08 00:57:30"} }},
  { '$project' : { '_id':0, 'my_id': '$my_id', 'time' : '$data.time', 'value' : '$data.value'} }
])

document = testcoll.find(query)
for i in document:
    print(i)

It shows document values as None in debugger and thus throws error:

TypeError: 'NoneType' object is not iterable

How can I run the query in python. Thanks

python driver should have documentation on mongodb site, with examples and everything. Have you checked that out? — Sergio Tulentsev
– Sergio Tulentsev, Commented Sep 12, 2018 at 11:36

Sagar Pandey · Accepted Answer · 2018-09-12 11:41:06Z

2

You can use the same query of mongo in python to run

query = [
  { '$unwind' :'$data'},
  { '$match' : {'type': 'data1', "my_id" : "44ef", 'data.time': { '$gte' : "2018-07-07 00:00:30" , '$lte' : "2018-07-08 00:57:30"} }},
  { '$project' : { '_id':0, 'my_id': '$my_id', 'time' : '$data.time', 'value' : '$data.value'} }
]
document = testcoll.aggregate(query)
for i in document:
    print(i)

answered Sep 12, 2018 at 11:41

Sagar Pandey

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Comments

Jab · Accepted Answer · 2018-09-12 11:56:14Z

As the documentation states, you need to use the aggregate function.

query = ([
  { '$unwind' :'$data'},
  { '$match' : {'type': 'data1', "my_id" : "44ef", 'data.time': { '$gte' : "2018-07-07 00:00:30" , '$lte' : "2018-07-08 00:57:30"} }},
  { '$project' : { '_id':0, 'my_id': '$my_id', 'time' : '$data.time', 'value' : '$data.value'} }
])

document = testcoll.aggregate(query)
for i in document:
    print(i)

Also, seems you are new to pymongo but something to look into. PyMongo is great but every interaction you make with it is blocking. Consider using Motor it allows for async/await (or even Flask if that's what you use) Almost all the same functions work with it but they are non blocking.

With motor it would just become:

document = await testcoll.aggregate(query)

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