Python [mongo] - 转换 find() 的返回字段

Question

need to get specific fields from Mongo, The DB is huge so I prefer getting the values in right format and not post processing it.

in example, There are 2 fields which need to convert the format:

1_id: ObjectId('604e0dbc96a0c93a45bfc5b0') to string as "604e0dbc96a0c93a45bfc5b0: 2.birthdate: ISODate('1999-11-10T00:00:00.000Z') - to string in date format "10/11/1999".

Example of json in MongoDB:

{
    _id: ObjectId('604e0dbc96a0c93a45bfc5b0'),
    address: 'BOB addrees',
    name: 'BOB',
    last_name: 'Habanero',
    birthdate: ISODate('1000-11-10T00:00:00.000Z')
}

retrieving the Jsons specific fields:

customers_cursor =  DB.customer.find({},{"_id": 1,"name" :1 ,"last_name":1 ,"customer_type":1,"address.0":1 ,"email":1 ,"birthdate" :1 ,"customer_status":1} )

Is there an option to use convert functions for returning values in find()? case not, what are my best option to do it while i have several fields required to format the values and there are MILLION of records in the MongoDB?

Answer 1

Demo - https://mongoplayground.net/p/4OcF0O74PvU

You've to use an aggregation query to do that.

convert object to string using $toString

Use $dateToString to format your date

db.collection.aggregate([
  {
    "$project": {
      "_id": {
        "$toString": "$_id"
      },
      "name": 1,
      "last_name": 1,
      "customer_type": 1,
      "address.0": 1,
      "email": 1,
      "birthdate": {
        "$dateToString": {
          "format": "%d/%m/%Y",
          "date": "$birthdate"
        }
      },
      "customer_status": 1
    }
  }
])