Insert and update operation

Important note: This article is in relation to online MongoDB course. For more information about the course and other posts describing its content please check my main page here: M101P: MongoDB for Developers course. 

Update or insert a new record into a document if it doesn't exist.

 
> db.arrays.find()
{ "_id" : ObjectId("52ba1c78a83c1ee5e6c903a1"), "a" : 1, "tab" : [  11,  22,  "hello" ] }

> db.arrays.update( { a: 2}, { $set : { "tab.2" : "london" } } )
> db.arrays.find()
{ "_id" : ObjectId("52ba1c78a83c1ee5e6c903a1"), "a" : 1, "tab" : [  11,  22,  "hello" ] }


> db.arrays.update( { a: 2}, { $set : { "tab.2" : "london" } }, { upsert: true} )
> db.arrays.find()
{ "_id" : ObjectId("52ba1c78a83c1ee5e6c903a1"), "a" : 1, "tab" : [  11,  22,  "hello" ] }
{ "_id" : ObjectId("52ba1e4cc1207a4a1fdeb3ac"), "a" : 2, "tab" : { "2" : "london" } }

> db.arrays.update( { a: 3}, { $set : { "mystr" : "poland" } }, { upsert: true} )
> db.arrays.find()
{ "_id" : ObjectId("52ba1c78a83c1ee5e6c903a1"), "a" : 1, "tab" : [  11,  22,  "hello" ] }
{ "_id" : ObjectId("52ba1e4cc1207a4a1fdeb3ac"), "a" : 2, "tab" : { "2" : "london" } }
{ "_id" : ObjectId("52ba1e99c1207a4a1fdeb3ad"), "a" : 3, "mystr" : "poland" }