Borrowed models

Borrow strings and slices directly from JSON input.

Declarations with lifetimes use the same Model derive and parse through BorrowModel. The input buffer must outlive the model’s use.

use rydantic::{BorrowModel, Model};
use std::borrow::Cow;

#[derive(Debug, Model)]
struct View<'a> {
    #[model(trim)]
    name: &'a str,
    #[model(trim, lowercase)]
    note: Cow<'a, str>,
}

let input = String::from(r#"{"name":" Alice ","note":" HELLO\nWORLD "}"#);
let view = View::parse_json(&input)?;
assert_eq!(view.name, "Alice");
assert_eq!(view.note, "hello\nworld");

&str references the original, unescaped JSON string. trim preserves the borrow by slicing it. Use Cow<str> when decoding escapes or changing case may require allocation. Inputs that require allocation for an &str field return borrowed_string or borrowed_transform errors. A before callback produces an owned JSON value and works with Cow or owned fields.

Borrowed models support nesting, recursion, generics, multiple lifetimes, collections, flattening, Serde from_str/from_slice, and the read-only BorrowValidated wrapper. parse_slice borrows from a byte buffer; reader-based entry points work with owned models.