Nested Arrays

[gotdan]

Hi,

It looks like mingo doesn't correctly return values in nested arrays. For example, with this data set:

var data = [{
    key0: [{
        key1: [ {key2: "value2"} ],
        key1a: {key2a: "value2a"}
    }]
}];

The expression {"key0.key1a.key2a": "value2a"} returns the object, while the expression {"key0.key1.key2": "value2"} returns an empty array. Am I constructing the query wrong?

Thanks,
Dan

[kofrasa]

I think your query should be valid but I have to confirm it with MongoDB's behaviour. I remember there were some limitations with the level of nesting in array queries but the current MongoDB version is 3.0 so things might work differently.

Anyway an equally viable alternative for what you are trying to achieve would be to use the $elemMatch operator such as {"key0.key1": {"$elemMatch": {key2: "value2"}}}

[gotdan]

Thanks - I’m not sure $elemMatch will work with this dataset though, since in some cases the value will be an object and and in some the same key will have an array of objects as the value (depending on how many children there are). I don’t have control over the data format, so one of the nice things about the mongo dot notation is that the same query should work in both cases.

Do you know if there is a way to use $elemMatch or another operator to handle this use case?

[kofrasa]

In that case you could use an $or operator (a bit of a hack i guess) :).

{$or: [
  {"key0.key1": {"$elemMatch": {key2: "value2"}}},
  {"key0.key1.key2": "value2"}
]}

I will look into the bug soon.

[kofrasa]

Just release 0.6.1 that fixes the issue.

[gotdan]

Thanks! That was faster than I could implement a work around :).