Flatten does not work as expected when using a top-level field from a vector message

[teeohhem]

When using the flatten operation, referencing a field (that contains an object) from an event results in a no-op. This is because when you reference a field from a vector event, you are just given the value, which in this case, is just an object without a key. Therefore, obviously, there is nothing to flatten.

I personally would expect the flatten operation to "just work" and flatten with the key into the main event.

Here's an example:

Event

{
    "timestamp": 1245542,
    "errors": {
        "code": 1234,
        "message": "invalid type",
        "class": "EventHelper"
    },
    "otherKey:" {
        "id": 1
    }
}

VRL

    flattened,err = flatten(.errors)

Expected:

{
    "timestamp": 1245542,
    "errors.code": 1234,
    "errors.message": "Invalid type",
    "errors.class": "EventHelper",
    "otherKey:" {
        "id": 1
    }
}

Actual:
No change to the event.

[pront]

Hi @teeohhem, I used your inputs here and the result looks OK.

Btw, your JSON event is missing some ,s.

[teeohhem]

Hi @pront . Thanks for the response. I fixed my JSON event above. Yes, with . it works. But what if I just want to flatten errors?

Here's the example: here

Here is my workaround/desired behavior: here

[pront]

For flattening the "errors" only see this example.

This example might help understand the differences.

[teeohhem]

@pront

For flattening the "errors" only see this example.

I'm arguing that if I want to flatten .errors, it would flatten the entire .errors object with each key having an errors key prefix.

In other words
flattening

{
    "errors": {
        "code": 1234,
        "message": "This is my message"
    }
}

should result in:

{
    "errors.code": 1234,
    "errors.message": "This is my message"
}