How to update data in nested array in MongoDB

Question

How to update a values in the nested array my code like below:-

{
 "cats" : [
 {
 "catId" : "1",
 "catname" : "elect",
 "displayname" : "Elect",
 "subcat" : [
 {
 "subcatname" : "lap",
 "subcatId" : "1",
 "displayname" : "Laptops"
 },
 {
 "subcatname" : "cam",
 "subcatId" : "2",
 "displayname" : "Camera"
 }
 ]
 },
 {
 "catId" : "2",
 "catname" : "auto",
 "displayname" : "Auto",
 "subcat" : [
 {
 "subcatname" : "car",
 "subcatId" : "1",
 "displayname" : "Car"
 },
 {
 "subcatname" : "byk", // i want MoterCycle here
 "subcatId" : "2",
 "displayname" : "Byke"
 }
 ]
 }
 ]
 }

I want to update a value of subcatname byk to MoterCycle How to write a query for mycode Best Regards GSY

Answer 1

Use the positional operator. Reference.

Your query:

db.cats.update(
 {"catId":"2", "subcat.subcatId" : "2"}, 
 {$set: {"subcat.$.subcatname": "MotorCycle"}}
 )

EDIT: It IS working. Here is my test:

> db.cats.find();
{ "_id" : ObjectId("52a15c7631282cd86d9fc1ef"), "catId" : "1", "catname" : "elect", "displayname" : "Elect", "subcat" : [ { "subcatname" : "lap", "subcatId" : "1", "displayname" : "Laptops" }, { "subcatname" : "cam", "subcatId" : "2", "displayname" : "Camera" } ] }
{ "_id" : ObjectId("52a15c7931282cd86d9fc1f0"), "catId" : "2", "catname" : "auto", "displayname" : "Auto", "subcat" : [ { "subcatname" : "car", "subcatId" : "1", "displayname" : "Car" }, { "subcatname" : "byk", "subcatId" : "2", "displayname" : "Byke" } ] }
> db.cats.update(
... {"catId":"2", "subcat.subcatId" : "2"}, 
... {$set: {"subcat.$.subcatname": "MotorCycle"}}
... )
> db.cats.find();
{ "_id" : ObjectId("52a15c7631282cd86d9fc1ef"), "catId" : "1", "catname" : "elect", "displayname" : "Elect", "subcat" : [ { "subcatname" : "lap", "subcatId" : "1", "displayname" : "Laptops" }, { "subcatname" : "cam", "subcatId" : "2", "displayname" : "Camera" } ] }
{ "_id" : ObjectId("52a15c7931282cd86d9fc1f0"), "catId" : "2", "catname" : "auto", "displayname" : "Auto", "subcat" : [ { "subcatname" : "car", "subcatId" : "1", "displayname" : "Car" }, { "displayname" : "Byke", "subcatId" : "2", "subcatname" : "MotorCycle" } ] }
> 

• sagar: i test it its not Working
• Lachezar Balev: I also test it and it is working :-) check the edit of my answer, which is C&P from my mongo shell...