embedded_update.rb

# Problem: Given the following document in the database, I want to update
# Dave Gahan's second prescription for Dilaudid from a quantity of 45 to
# a quantity of 30.

{ "_id" : 1
  "name" : "Dave Gahan"
  "medications" : [
    { "id" : 23,
      "name" : "Dilaudid",
      "type" : "Rx",
      "prescriptions" : [
        { "id" : 13,
          "quantity" : 60,
          "started" : 2009-01-01
        },
        { "id" : 77,
          "quantity" : 45,
          "started" : 2009-02-01
        }
      ]
    },
    { "id" : 41,
      "name" : "Oxycodone",
      "type" : "Rx"
    }
  ]
}

# First try was using 1.3.4 $ positional locator... These do not find the
# document embedded multiple levels:

collection.update(
  { "_id" : 1, "medications._id" : 23, "medications.prescriptions._id" : 77 },
  { $set : { "medications.prescriptions.$.quantity" : 30 } },
  false,
  true
)

collection.update(
  { "_id" : 1, "medications._id" : 23, "medications.prescriptions._id" : 77 },
  { $set : { "medications.$.prescriptions.$.quantity" : 30 } },
  false,
  true
)

# What I would like is to be able to match on mutliples, given a syntax like the following:

collection.update(
  { "_id" : 1, "medications._id" : 23, "medications.prescriptions._id" : 77 },
  { $set : { "medications.$0.prescriptions.$1.quantity" : 30 } },
  false,
  true
)

is there any update for this?