MongoDB - Database References
Referenced Relationships additionally called Manual References wherein we manually save the referenced record's id inner other record. However, in instances where a record incorporates references from exceptional collections, we can use MongoDB DBRefs.
DBRefs vs Manual ReferencesAs an instance scenario, in which we might use DBRefs in preference to guide references, recall a database wherein we are storing different types of addresses (home, office, mailing, and so on.) in different collections (address_home, address_office, address_mailing, and so forth).
Using DBRefsThere are 3 fields in DBRefs
$ref − This subject specifies the gathering of the referenced record
$identification − This discipline specifies the _id field of the referenced file
$db − This is an optional discipline and includes the call of the database wherein the referenced record lies
"_id":ObjectId("CfLbW+g4r9M.6F"), "cope with": "$ref": "address_home", "$identification": ObjectId("CfLbW+g4r9M.6F"), "$db": "welookups", "touch": "987654321", "dob": "11-12-2000", "call": "David"The cope with DBRef area right here specifies that the referenced deal with record lies in address_home series under welookups database and has an identification of CfLbW+g4r9M.6F. The following code dynamically looks inside the series distinctive with the aid of $ref parameter (address_home in our case) for a file with identification as precise through $id parameter in DBRef.
>var consumer = db.Customers.FindOne("name":"David") >var dbRef = consumer.Deal with >db[dbRef.$ref].FindOne("_id":(dbRef.$id))