Query an array in MongoDB to fetch a specific value

To fetch a specific value from an array, use aggregate() along with $project. Let us create a collection with documents −

> db.demo761.insertOne( ...    { ...       "details": [ ...          { ...             "student": { ...                "FullName": "Chris Brown" ...             } ...          } ...       ] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb034d15637cd592b2a4af1") } > db.demo761.insertOne( ...    { ...       "details": [ ...          { ...             "student": { ...                "FullName": "Chris Taylor" ...             } ...          } ...       ] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb034d25637cd592b2a4af2") }

Display all documents from a collection with the help of find() method −

> db.demo761.find();

This will produce the following output −

{ "_id" : ObjectId("5eb034d15637cd592b2a4af1"), "details" : [ { "student" : { "FullName" : "Chris Brown" } } ] } { "_id" : ObjectId("5eb034d25637cd592b2a4af2"), "details" : [ { "student" : { "FullName" : "Chris Taylor" } } ] }

Following is how to query an array in MongoDB −

> db.demo761.aggregate([ ...    {'$unwind':'$details'}, ...    {'$match': { ...       'details.student.FullName':'Chris Taylor', ...    }}, ...    {'$project': { ...       'details.student.FullName': 1, '_id': 0 ...    }}, ... ])

This will produce the following output −

{ "details" : { "student" : { "FullName" : "Chris Taylor" } } }