How to correctly query a MongoDB nested document with python?

问题

Background: I just learned the basics of databases and mongo this week.

I have a collection named 'orderstest' of 10K documents with the following basic form:

{
    "_id": {
        "$oid": "2309823082039482"
    },
    "Order": "12345678920000",
    "Client": "Client Name Inc.",
    "OrderUId": "3452-2342-9393-0100",
    "OrderItems": [
        {
            "Client": "Client Name Inc.",
            "Details": [
                {
                    "Key": "EnterpriseCode",
                    "Value": "XYZ1000"
                },
                {
                    "Key": "AWSRegion",
                    "Value": "Frankfurt"
                },

            ],
            "ProductUId": "A90",
            "OrderItemUId": "ABC1000",
        }
    ],
    "__v": 0
}

I have to create a python3 script to compare these entries with some AWS info. The 1st thing I need to do is to obtain all the documents whose ProductUId matches "A90" or "B90".

I ran this query in the mongo shell and it worked:

db.orderstest.find({
  OrderItems:{$elemMatch: {
                     ProductUId:"A90"
                 
                } 

}
})

But when I try to put this inside my script, it throws this error:

    'OrderItems':{'$elemMatch': {
                               ^
SyntaxError: invalid character in identifier

Also, I need to create the condition of all "A90" or "B90" which from reading the documentation and trying out tweaking a few things I was never able to implement. I should also state that I have gone through the MongoDB docs for several hours but it makes absolutely no sense to me, I guess due to my null experience with DBs in general.

回答1:

For "The 1st thing I need to do is to obtain all the documents whose ProductUId matches "A90" or "B90"."

.find({"OrderItems.ProductUId": {"$in":["A90","B90"]}})

Will work. Not sure why you're using $elemMatch, it doesn't seem necessary?

来源：https://stackoverflow.com/questions/51295266/how-to-correctly-query-a-mongodb-nested-document-with-python

标签

python

python-3.x

mongodb

pymongo