I have a structure that looks like this:

{
  _id: 10,
  line_items: [
      { 
        _id: 2,
        name: "name",
        quantity: 2,
      },
      { 
        _id: 3,
        name: "name2",
        quantity: 1,
      }
    ],
    sub_total: 100
  }

And i'm trying to do an update:

query={_id: 10, 'line_items.$._id': 2}
db.orders.update(query, {$push: {$inc: {'line_items.$.quantity': 1}}, $inc: {sub_total: 32}})

But it doesn't do anything and doesn't show any errors. What's wrong?

CodePudding user response：

There are several issues with your attempt:

1. you need to use $elemMatch when querying array fields for your case
2. your $push is incorrect. you can simply use $inc

Here is a working solution:

db.collection.update({
  _id: 10,
  line_items: {
    $elemMatch: {
      _id: 2
    }
  }
},
{
  $inc: {
    "line_items.$.quantity": 1,
    sub_total: 32
  }
})

Here is the Mongo playground for your reference.