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Array index or indexing inner items in MongoDB to fetch values
At first, let us create a collection with documents and also use ensureIndex() to create an index −
> db.demo323.insertOne({"details":{"Name":"Chris","Age":34}}); { "acknowledged" : true, "insertedId" : ObjectId("5e51157af8647eb59e56206e") } > db.demo323.insertOne({"details":{"Name":"David","Age":31}}); { "acknowledged" : true, "insertedId" : ObjectId("5e511581f8647eb59e56206f") } > db.demo323.insertOne({"details":{"Name":"Bob","Age":28}}); { "acknowledged" : true, "insertedId" : ObjectId("5e511589f8647eb59e562070") } > db.demo323.ensureIndex({"details.Name":1}); { "createdCollectionAutomatically" : false, "numIndexesBefore" : 2, "numIndexesAfter" : 3, "ok" : 1 }
Display all documents from a collection with the help of find() method −
> db.demo323.find();
This will produce the following output −
{ "_id" : ObjectId("5e51157af8647eb59e56206e"), "details" : { "Name" : "Chris", "Age" : 34 } } { "_id" : ObjectId("5e511581f8647eb59e56206f"), "details" : { "Name" : "David", "Age" : 31 } } { "_id" : ObjectId("5e511589f8647eb59e562070"), "details" : { "Name" : "Bob", "Age" : 28 } }
Following is the query to find values from the array −
> db.demo323.find({"details.Name":"Bob"});
This will produce the following output −
{ "_id" : ObjectId("5e511589f8647eb59e562070"), "details" : { "Name" : "Bob", "Age" : 28 } }
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