mongodb : Update document

“update” method of collection is used to update a document.

Syntax

db.collection.update(query, update, options)

“update” method is used to update an existing document (or) documents in the collection. Depending on options in the query, update method update/replace the document.

Detailed syntax looks like below.

db.collection.update(

   <query>,

   <update>,

   {

     upsert: <boolean>,

     multi: <boolean>,

     writeConcern: <document>

   }

)

Parameter	Type	Description
query	document	The selection criteria for the update.
update	document	The modifications to apply.
upsert	boolean	Optional. If set to true, creates a new document when no document matches the query criteria. The default value is false, which does not insert a new document when no match is found.
multi	boolean	Optional. If set to true, updates multiple documents that meet the query criteria. If set to false, updates one document. The default value is false.
writeConcern	document	Optional. A document expressing the write concern.

 

> db.employee.find()
{ "_id" : 1, "firstName" : "Joel", "lastName" : "chelli", "salary" : 25000, "hobbies" : [ "watching movies", "playing games" ] }
{ "_id" : 2, "firstName" : "Ananad", "lastName" : "Bandaru", "salary" : 200000, "hobbies" : [ "car drivinig", "watching movies" ] }
{ "_id" : 3, "firstName" : "Gopi", "lastName" : "Battu", "salary" : 65000, "hobbies" : [ "climbing hills", "dancing", "singing" ] }
{ "_id" : 4, "firstName" : "Ritwik", "lastName" : "Mohenthy", "salary" : 50000, "hobbies" : [ "watching movies", "watching movies", "watching movies" ] }
{ "_id" : 5, "firstName" : "RamaKrishna", "lastName" : "Gurram", "salary" : 150000, "hobbies" : [ "hackning sites", "Reading books", "listening music" ] }
{ "_id" : 6, "firstName" : "BalaKrishna", "lastName" : "Gurram", "salary" : 80000, "hobbies" : [ "roaming around", "eating food" ] }
{ "_id" : ObjectId("54ba2de1f1c8f2149c000740"), "name" : "Krishna", "project" : "A350" }
{ "_id" : ObjectId("54ba2dfcf1c8f2149c000741"), "name" : "Krishna", "project" : 4 }
{ "_id" : ObjectId("54ba47c9f1c8f2149c000742"), "name" : "Keerthi", "hobbies" : [ "watching movies", "playing games", "cooking" ] }
>
>
> db.employee.update({"firstName" : "Joel"}, {"firstName" : "Jessi"})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
>
> db.employee.find()
{ "_id" : 1, "firstName" : "Jessi" }
{ "_id" : 2, "firstName" : "Ananad", "lastName" : "Bandaru", "salary" : 200000, "hobbies" : [ "car drivinig", "watching movies" ] }
{ "_id" : 3, "firstName" : "Gopi", "lastName" : "Battu", "salary" : 65000, "hobbies" : [ "climbing hills", "dancing", "singing" ] }
{ "_id" : 4, "firstName" : "Ritwik", "lastName" : "Mohenthy", "salary" : 50000, "hobbies" : [ "watching movies", "watching movies", "watching movies" ] }
{ "_id" : 5, "firstName" : "RamaKrishna", "lastName" : "Gurram", "salary" : 150000, "hobbies" : [ "hackning sites", "Reading books", "listening music" ] }
{ "_id" : 6, "firstName" : "BalaKrishna", "lastName" : "Gurram", "salary" : 80000, "hobbies" : [ "roaming around", "eating food" ] }
{ "_id" : ObjectId("54ba2de1f1c8f2149c000740"), "name" : "Krishna", "project" : "A350" }
{ "_id" : ObjectId("54ba2dfcf1c8f2149c000741"), "name" : "Krishna", "project" : 4 }
{ "_id" : ObjectId("54ba47c9f1c8f2149c000742"), "name" : "Keerthi", "hobbies" : [ "watching movies", "playing games", "cooking" ] }

As you observe “db.employee.update({"firstName" : "Joel"}, {"firstName" : "Jessi"})” method update document where “firstName” is “Joel”. Closely observe the result, actually it replaced entire document. The fields like “lastName”, “salary”, “hobbies” for the document 1 (_id=1) are no more. It is because, update method replace document with completely new document.

I will explain how to update specific fields in next post.

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