Writes data as a JSON object, and includes field values optionally. The specified fields will be formatted as JSON and assigned to the field specified in as, defaults to _json.

ParameterTypeRequiredDefault ValueDescription
asstringoptional[a]_json Name of output field.
field[b]array of stringsoptional[a]@rawstring Values and fields that should be converted to JSON. Accepts either a value or array of values. Values are interpreted as prefix matches, unless a globbing pattern with * is given (see following example).

[a] Optional parameters use their default value unless explicitly set.

[b] The parameter name field can be omitted.

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writeJson() Examples

  • Multiple fields can be included. Given events where:

    json
    a.b.c=5,
    a.b.e[0]=6,
    a.d=7,
    a.f.g=8

    use the query function to call:

    logscale
    writeJson(["a.b.c", "a.b.e[0]", "a.d", "a.f.g"])

    It will write the following JSON to each event, respectively:

    json
    {"a":{"b":{"c":5}}},
    {"a":{"b":{"e":[6]}}},
    {"a":{"d":7}},
    {"a":{"f":{"g":8}}}
  • Arguments passed to the field parameter are interpreted as prefix matches. For example, the query:

    logscale
    writeJson(field=["a.b"])

    matches:

    json
    a.b.c
     a.bc
     a.b[0]
     a.b!
    …
  • Array-glob patterns can be passed to the field parameter. For example, the query:

    logscale
    writeJson(field=["a.b[*]"])

    matches all fields in the event and it also matches anything else that starts with a:

    json
    a.b[0]
     a.b[0]c
     a.b[0].c
     a.b[0][0]
     a.b[0]!
     ...
     a.b[1]c
     a.b[1].c
     a.b[1][0]
     a.b[1]!
    …