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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" } } }
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