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Is it possible to use MongoDB field value as pattern in $regex?
Yes, for this, use $indexOfCP operator along with aggregate framework. Let us first create a collection with documents −
> db.patterDemo.insertOne( { "ClientName": "John", "ClientWebsiteName":"webbuziness.com/John/business" } ); { "acknowledged" : true, "insertedId" : ObjectId("5cea40acef71edecf6a1f68d") } > db.patterDemo.insertOne( { "ClientName": "Carol", "ClientWebsiteName":"solvecoding.com/business" } ); { "acknowledged" : true, "insertedId" : ObjectId("5cea40acef71edecf6a1f68e") }
Following is the query to display all documents from a collection with the help of find() method −
> db.patterDemo.find().pretty();
This will produce the following output −
{ "_id" : ObjectId("5cea40acef71edecf6a1f68d"), "ClientName" : "John", "ClientWebsiteName" : "abcd.com" } { "_id" : ObjectId("5cea40acef71edecf6a1f68e"), "ClientName" : "Carol", "ClientWebsiteName" : "pqrs.com" }
Following is the query to use field value as pattern in $regex −
> db.patterDemo.aggregate([ { "$match": { "$expr": { "$ne": [ { "$indexOfCP": ["$ClientWebsiteName", "$ClientName"] }, -1 ] } }} ]);
This will produce the following output −
{ "_id" : ObjectId("5cea40acef71edecf6a1f68d"), "ClientName" : "John", "ClientWebsiteName" : "abcd.com" }
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