Struct JsonFormat 

pub struct JsonFormat { /* private fields */ }

Available on crate feature json only.

JSON formatter.

The default configuration emits compact JSON with a trailing newline. Set Self::pretty for an indented form intended for developer eyeballs, not machine ingestion.

Example

use log_io::format::{Format, JsonFormat};
use log_io::{Field, Level, Metadata, Record, Value};

let fmt = JsonFormat::new();
let fields = [Field::new("port", Value::U64(8080))];
let record = Record::new(Metadata::new(Level::Info, "app"), "started", &fields);

let mut out = String::new();
fmt.write_record(&record, &mut out).unwrap();

assert!(out.starts_with('{'));
assert!(out.ends_with("}\n"));
assert!(out.contains("\"port\":8080"));

Implementations

impl JsonFormat

pub const fn new() -> Self

New compact JSON formatter. Equivalent to Self::default().

pub const fn pretty(self, enabled: bool) -> Self

Toggle pretty (multi-line, indented) output.

pub const fn timestamp_rfc3339(self, enabled: bool) -> Self

Emit timestamps as RFC 3339 strings instead of unix nanoseconds.

When enabled and a record’s timestamp is present, the output looks like "timestamp":"2026-05-18T13:24:01.123456789Z". When disabled (default), it is "timestamp":1700000000000000000.

Trait Implementations

impl Clone for JsonFormat

fn clone(&self) -> JsonFormat

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for JsonFormat

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for JsonFormat

fn default() -> JsonFormat

Returns the “default value” for a type.

impl Format for JsonFormat

fn write_record<W: Write + ?Sized>( &self, record: &Record<'_>, writer: &mut W, ) -> Result

Write the record to writer using a core::fmt::Write sink.

impl Copy for JsonFormat