flatten

Flattens nested data.

flatten(x:record) -> record

Description

The flatten function takes a record and performs actions of contained container types:

1. Records: Join nested records with a separator (. by default). For example, if a field named x is a record with fields a and b, flattening will lift the nested record into the parent scope by creating two new fields x.a and x.b.
2. Lists: Merge nested lists into a single (flat) list. For example, [[[2]], [[3, 1]], [[4]]] becomes [2, 3, 1, 4].

For records inside lists, flatten "pushes lists down" into one list per record field. For example, the record

{
  foo: [
    {
      a: 2,
      b: 1,
    },
    {
      a: 4,
    },
  ],
}

becomes

{
  "foo.a": [
    2,
    4,
  ],
  "foo.b": [
    1,
    null,
  ],
}

Lists nested in records that are nested in lists will also be flattened. For example, the record

{
  foo: [
    {
      a: [
        [2, 23],
        [1,16],
      ],
      b: [1],
    },
    {
      a: [[4]],
    },
  ],
}

becomes

{
  "foo.a": [
    2,
    23,
    1,
    16,
    4
  ],
  "foo.b": [
    1
  ]
}

As you can see from the above examples, flattening also removes null values.

sep = string (optional)

The separator to use for joining field names.

Defaults to ".".

Examples

Flatten fields with the dot character

from {
  src_ip: 147.32.84.165,
  src_port: 1141,
  dest_ip: 147.32.80.9,
  dest_port: 53,
  event_type: "dns",
  dns: {
    type: "query",
    id: 553,
    rrname: "irc.freenode.net",
    rrtype: "A",
    tx_id: 0,
    grouped: {
      A: [
        "tenzir.com",
      ],
    },
  },
}
this = flatten(this)

{
  src_ip: 147.32.84.165,
  src_port: 1141,
  dest_ip: 147.32.80.9,
  dest_port: 53,
  event_type: "dns",
  "dns.type": "query",
  "dns.id": 553,
  "dns.rrname": "irc.freenode.net",
  "dns.rrtype": "A",
  "dns.tx_id": 0,
  "dns.grouped.A": ["tenzir.com"],
}

See Also

unflatten