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Implement $dateToString on array items with MongoDB
To implement $dateToString on array items, use aggregate() in MongoDB. Let us create a collection with documents −
> db.demo104.insertOne( ... { ... ... "AppName" : "Online Book", ... "Details" : [ ... { ... "ClientName" : "Chris", ... "Deadline" : new ISODate("2020-03-10") ... } ... ] ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e2ed7fd9fd5fd66da21446f") }
Display all documents from a collection with the help of find() method −
> db.demo104.find().pretty();
This will produce the following output −
{ "_id" : ObjectId("5e2ed7fd9fd5fd66da21446f"), "AppName" : "Online Book", "Details" : [ { "ClientName" : "Chris", "Deadline" : ISODate("2020-03-10T00:00:00Z") } ] }
Following is the query to implement $dateToString on array items −
> db.demo104.aggregate([ ... { "$match": {}}, ... { "$project": { ... "title": 1, ... "Details": { ... "$map": { ... "input": "$Details", ... "as": "out", ... "in": { ... "ClientName": "$$out.ClientName", ... "Deadline": { ... "$dateToString": { "format": "%m", "date": "$$out.Deadline" } ... } ... } ... } ... } ... }} ... ])
This will produce the following output −
{ "_id" : ObjectId("5e2ed7fd9fd5fd66da21446f"), "Details" : [ { "ClientName" : "Chris", "Deadline" : "03" } ] }
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