Mongodb Increment value inside nested array

Question

I´m using mongotemplate for Spring, and I was wondering how I could increment a value of one of my documents that I have in an array atomically. Imagine that we have

{'a':1,
   b:[{_id:341432,
       c:2
      },
      {_id:341445,
       c:3
      }]};

What I would like is increment c from 3 to 4 for the _id 341445

I have been using findAndModify but I dont know how can I make it for a nested document in an array.

Regards.

So far the only thing that I found is determinate the index of the array like b.0.c=11111 any better idea? — paul
– paul, Commented Apr 16, 2013 at 14:15

Linda Qin · Accepted Answer · 2013-04-17 01:05:02Z

45

To update an element in an array field, you can use the positional $ operator

For example, the following js increments c from 3 to 4 for _id 341445:

db.collection.update({a:1, "b._id":341445} , {$inc:{"b.$.c":1}})

answered Apr 17, 2013 at 1:05

Linda Qin

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4 Comments

paul Over a year ago

Thanks!, but remember that your answer have to be extrapolated to Java

Naveen Kumar Over a year ago

This will not work when the update query is used with upsert.

Box and Cox Over a year ago

Thank You Thank You Thank You. I've been spending three+ hours trying to get this to work!!! Great answer!!

destan Over a year ago

@Lind Qin, thanks it works. Here spring data solution for the ones who might be interested:

mongoOperations.updateFirst(new Query(Criteria.where("a").is(1).and("b._id").is(341445)),new Update().inc("b.$.c", 1), YourClass.class);

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