Queries with dot notation

Dot notation is used to query nested documents.

Let’s say I had below data in person collection.

db.person.insert(
[
 {
  "name" : "Hari Krishna",
  "address" :{
   "home" : {
    "city" : "ongole",
    "state" : "Andhra Pradesh",
    "country" : "India"
   },
   "office" : {
    "city" : "Bangalore",
    "state" : "Karnataka",
    "country" : "India"
   } 
  }
 },
 {
  "name" : "PTR",
  "address" :{
   "home" : {
    "city" : "Gudivada",
    "state" : "Andhra Pradesh",
    "country" : "India"
   },
   "office" : {
    "city" : "Hyderabad",
    "state" : "Andhra Pradesh",
    "country" : "India"
   } 
  }
 }
]
)

> db.person.find().pretty()
{
        "_id" : ObjectId("54ba5928f1c8f2149c000743"),
        "name" : "Hari Krishna",
        "address" : {
                "home" : {
                        "city" : "ongole",
                        "state" : "Andhra Pradesh",
                        "country" : "India"
                },
                "office" : {
                        "city" : "Bangalore",
                        "state" : "Karnataka",
                        "country" : "India"
                }
        }
}
{
        "_id" : ObjectId("54ba5928f1c8f2149c000744"),
        "name" : "PTR",
        "address" : {
                "home" : {
                        "city" : "Gudivada",
                        "state" : "Andhra Pradesh",
                        "country" : "India"
                },
                "office" : {
                        "city" : "Hyderabad",
                        "state" : "Andhra Pradesh",
                        "country" : "India"
                }
        }
}

1. Get document where home city is “ongole”.

> db.person.find({"address.home.city" : "ongole"}).pretty()
{
        "_id" : ObjectId("54ba5928f1c8f2149c000743"),
        "name" : "Hari Krishna",
        "address" : {
                "home" : {
                        "city" : "ongole",
                        "state" : "Andhra Pradesh",
                        "country" : "India"
                },
                "office" : {
                        "city" : "Bangalore",
                        "state" : "Karnataka",
                        "country" : "India"
                }
        }
}

As you see, . notation is used to get the home city like “address.home.city”.

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