Find in a dictionary like structure by value with MongoDB?

To find documents in a dictionary-like structure by value in MongoDB, use dot notation to specify the exact path to the nested field you want to search.

Syntax

db.collection.find({
    "parentObject.nestedObject.fieldName": "searchValue"
});

Sample Data

Let us first create a collection with nested dictionary-like documents :

db.findInDictionaryDemo.insertMany([
    {
        "_id": 101,
        "AllCustomerDetails": {
            "SomeCustomerDetail1": {
                "CustomerName1": "John Doe",
                "CustomerName2": "John Smith"
            },
            "SomeCustomerDetail2": {
                "CustomerName1": "Carol Taylor",
                "CustomerName2": "David Miller"
            }
        }
    },
    {
        "_id": 102,
        "AllCustomerDetails": {
            "SomeCustomerDetail1": {
                "CustomerName1": "Sam Williams",
                "CustomerName2": "Bob Johnson"
            },
            "SomeCustomerDetail2": {
                "CustomerName1": "Chris Brown",
                "CustomerName2": "Mike Wilson"
            }
        }
    }
]);

{
    "acknowledged": true,
    "insertedIds": [101, 102]
}

Display All Documents

db.findInDictionaryDemo.find().pretty();

{
    "_id": 101,
    "AllCustomerDetails": {
        "SomeCustomerDetail1": {
            "CustomerName1": "John Doe",
            "CustomerName2": "John Smith"
        },
        "SomeCustomerDetail2": {
            "CustomerName1": "Carol Taylor",
            "CustomerName2": "David Miller"
        }
    }
}
{
    "_id": 102,
    "AllCustomerDetails": {
        "SomeCustomerDetail1": {
            "CustomerName1": "Sam Williams",
            "CustomerName2": "Bob Johnson"
        },
        "SomeCustomerDetail2": {
            "CustomerName1": "Chris Brown",
            "CustomerName2": "Mike Wilson"
        }
    }
}

Find by Nested Value

Search for documents where CustomerName2 in SomeCustomerDetail2 equals "Mike Wilson" :

db.findInDictionaryDemo.find({
    "AllCustomerDetails.SomeCustomerDetail2.CustomerName2": "Mike Wilson"
}).pretty();

{
    "_id": 102,
    "AllCustomerDetails": {
        "SomeCustomerDetail1": {
            "CustomerName1": "Sam Williams",
            "CustomerName2": "Bob Johnson"
        },
        "SomeCustomerDetail2": {
            "CustomerName1": "Chris Brown",
            "CustomerName2": "Mike Wilson"
        }
    }
}

Key Points

• Use dot notation to traverse nested objects: "parent.child.field"
• MongoDB searches the exact field path specified in the query
• Field names are case-sensitive in the dot notation path

Conclusion

MongoDB's dot notation allows precise querying of nested dictionary-like structures by specifying the complete path to the target field. This enables efficient searches within complex document hierarchies.