facet-pretty

Pretty-printing

facet-pretty renders any Facet value as readable, structured text without requiring Debug. Reach for it when you want friendly diagnostics, snapshots, logs, or quick inspection with the same shape information the rest of facet uses.

Install

Add facet and facet-pretty to your crate.

Minimal example

rust
use facet::Facet;
use facet_pretty::FacetPretty;

#[derive(Facet)]
struct Person {
    name: String,
    age: u32,
}

let person = Person {
    name: "Alice".to_string(),
    age: 30,
};

let rendered = person.pretty().to_string();
assert!(rendered.contains("Person"));
assert!(rendered.contains("Alice"));

.pretty() returns a Display wrapper, so it works anywhere {} formatting does: diagnostics, tracing fields, test output, or a tiny debug view.

Redaction

Mark a field #[facet(sensitive)] and facet-pretty replaces its value with [REDACTED] while keeping the field name visible:

rust
use facet::Facet;
use facet_pretty::FacetPretty;

#[derive(Facet)]
struct Config {
    host: String,

    #[facet(sensitive)]
    api_key: String,
}

let config = Config {
    host: "example.com".to_string(),
    api_key: "secret".to_string(),
};

let rendered = config.pretty().to_string();
assert!(rendered.contains("api_key"));
assert!(rendered.contains("[REDACTED]"));
assert!(!rendered.contains("secret"));

That makes it a good fit for operational output where secrets must never take a surprise stroll through the logs.

Custom output

Use PrettyPrinter when you want explicit formatting settings:

rust
use facet::Facet;
use facet_pretty::{FacetPretty, PrettyPrinter};

#[derive(Facet)]
struct Point {
    x: i32,
    y: i32,
}

let point = Point { x: 1, y: 2 };
let printer = PrettyPrinter::new().with_indent_size(4);

let rendered = point.pretty_with(printer).to_string();
assert!(rendered.contains("Point"));

PrettyPrinter::format(&value) is available too, if you prefer asking the printer for a String directly.

  • facet-error — derive displayable error types from doc comments
  • facet-json — serialize the same values as JSON
  • facet-validate — reject invalid values before printing them
  • Ecosystem — diagnostics, derive plugins, and format crates