How to lookup data from 2 collections in MongoDB using python

Question

I need read 2 collections data from MongoDB in Python, is there any way to join data in python?

Welcome to Stack Overflow! Please try something out first and show us an minimal code example... https://stackoverflow.com/help/how-to-ask — phrogg, Sep 25 '18 at 05:50
Similar to this perhaps : https://stackoverflow.com/q/2350495/9144250 — elpidaguy, Sep 28 '18 at 08:36

score 6 · Answer 1 · edited Jul 29 '21 at 12:27

Let's say that we have two collections(tables):

buy_orders
sell_orders

Those tables have the same field 'id_transaction' , and we want to join those tables on this field:

import pymongo

my_client = pymongo.MongoClient('mongodb://localhost:27017/')
my_db = my_client['Orders']
my_collection = my_db['buy_orders']
result = my_collection.aggregate([{
       '$lookup' : {'from': 'sell_orders','localField': 'id_transaction','foreignField': 'id_transaction','as': 'results' }
}])

To print results:

for item in result:
    print(item)

For more references: MongoDB Docs and PyMongo Docs

score 1 · Answer 2 · edited Jun 20 '20 at 09:12

Have a look here

from bson.objectid import ObjectId

#the custom_id for reference
custom_id = ObjectId()

#creating user with the role admin
db.users.insert_one({"name": "Boston", "role_id": custom_id})

#Creating role with the custom id
db.roles.insert_one({"_id": custom_id, "name": "Admin")}

#lookup usage
db.users.aggregate([
                {
                    "$lookup":
                    {
                        "from": "roles",
                        "localField": "role_id",
                        "foreignField": "_id",
                        "as": "roles"
                    }
                }
            ])

How to lookup data from 2 collections in MongoDB using python

2 Answers2

Have a look here