Struct Format

pub struct Format<F = Full, T = SystemTime> { /* private fields */ }

Available on crate features fmt and std only.

A pre-configured event formatter.

You will usually want to use this as the FormatEvent for a FmtSubscriber.

The default logging format, Full includes all fields in each event and its containing spans. The Compact logging format is intended to produce shorter log lines; it displays each event’s fields, along with fields from the current span context, but other information is abbreviated. The Pretty logging format is an extra-verbose, multi-line human-readable logging format intended for use in development.

Implementations

impl<F, T> Format<F, T>

pub fn compact(self) -> Format<Compact, T>

Use a less verbose output format.

See Compact.

pub fn pretty(self) -> Format<Pretty, T>

Available on crate feature ansi only.

Use an excessively pretty, human-readable output format.

See Pretty.

Note that this requires the “ansi” feature to be enabled.

Options

Format::with_ansi can be used to disable ANSI terminal escape codes (which enable formatting such as colors, bold, italic, etc) in event formatting. However, a field formatter must be manually provided to avoid ANSI in the formatting of parent spans, like so:

tracing_subscriber::fmt()
   .pretty()
   .with_ansi(false)
   .fmt_fields(format::PrettyFields::new().with_ansi(false))
   // ... other settings ...
   .init();

pub fn json(self) -> Format<Json, T>

Available on crate feature json only.

Use the full JSON format.

The full format includes fields from all entered spans.

Example Output

{"timestamp":"Feb 20 11:28:15.096","level":"INFO","target":"mycrate","fields":{"message":"some message", "key": "value"}}

Options

• Format::flatten_event can be used to enable flattening event fields into the root object.

pub fn with_timer<T2>(self, timer: T2) -> Format<F, T2>

Use the given timer for log message timestamps.

See time module for the provided timer implementations.

Note that using the "time" feature flag enables the additional time formatters UtcTime and LocalTime, which use the time crate to provide more sophisticated timestamp formatting options.

pub fn without_time(self) -> Format<F, ()>

Do not emit timestamps with log messages.

pub fn with_ansi(self, ansi: bool) -> Format<F, T>

Enable ANSI terminal colors for formatted output.

pub fn with_target(self, display_target: bool) -> Format<F, T>

Sets whether or not an event’s target is displayed.

pub fn with_level(self, display_level: bool) -> Format<F, T>

Sets whether or not an event’s level is displayed.

pub fn with_thread_ids(self, display_thread_id: bool) -> Format<F, T>

Sets whether or not the thread ID of the current thread is displayed when formatting events.

pub fn with_thread_names(self, display_thread_name: bool) -> Format<F, T>

Sets whether or not the name of the current thread is displayed when formatting events.

pub fn with_file(self, display_filename: bool) -> Format<F, T>

Sets whether or not an event’s source code file path is displayed.

pub fn with_line_number(self, display_line_number: bool) -> Format<F, T>

Sets whether or not an event’s source code line number is displayed.

pub fn with_source_location(self, display_location: bool) -> Self

Sets whether or not the source code location from which an event originated is displayed.

This is equivalent to calling Format::with_file and Format::with_line_number with the same value.

impl<T> Format<Json, T>

pub fn flatten_event(self, flatten_event: bool) -> Format<Json, T>

Available on crate feature json only.

Use the full JSON format with the event’s event fields flattened.

Example Output

{"timestamp":"Feb 20 11:28:15.096","level":"INFO","target":"mycrate", "message":"some message", "key": "value"}

See Json

pub fn with_current_span(self, display_current_span: bool) -> Format<Json, T>

Available on crate feature json only.

Sets whether or not the formatter will include the current span in formatted events.

See Json

pub fn with_span_list(self, display_span_list: bool) -> Format<Json, T>

Available on crate feature json only.

Sets whether or not the formatter will include a list (from root to leaf) of all currently entered spans in formatted events.

See Json

Trait Implementations

impl<F: Clone, T: Clone> Clone for Format<F, T>

fn clone(&self) -> Format<F, T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<F: Debug, T: Debug> Debug for Format<F, T>

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

Formats the value using the given formatter.

impl Default for Format<Full, SystemTime>

fn default() -> Self

Returns the “default value” for a type.

impl<C, N, T> FormatEvent<C, N> for Format<Compact, T>

where C: Collect + for<'a> LookupSpan<'a>, N: for<'a> FormatFields<'a> + 'static, T: FormatTime,

fn format_event( &self, ctx: &FmtContext<'_, C, N>, writer: Writer<'_>, event: &Event<'_>, ) -> Result

Write a log message for Event in Context to the given Writer.

impl<C, N, T> FormatEvent<C, N> for Format<Full, T>

where C: Collect + for<'a> LookupSpan<'a>, N: for<'a> FormatFields<'a> + 'static, T: FormatTime,

fn format_event( &self, ctx: &FmtContext<'_, C, N>, writer: Writer<'_>, event: &Event<'_>, ) -> Result

Write a log message for Event in Context to the given Writer.

impl<C, N, T> FormatEvent<C, N> for Format<Json, T>

where C: Collect + for<'lookup> LookupSpan<'lookup>, N: for<'writer> FormatFields<'writer> + 'static, T: FormatTime,

fn format_event( &self, ctx: &FmtContext<'_, C, N>, writer: Writer<'_>, event: &Event<'_>, ) -> Result

where C: Collect + for<'a> LookupSpan<'a>,

Write a log message for Event in Context to the given Writer.

impl<C, N, T> FormatEvent<C, N> for Format<Pretty, T>

where C: Collect + for<'a> LookupSpan<'a>, N: for<'a> FormatFields<'a> + 'static, T: FormatTime,

fn format_event( &self, ctx: &FmtContext<'_, C, N>, writer: Writer<'_>, event: &Event<'_>, ) -> Result

Write a log message for Event in Context to the given Writer.