deser-json

JSON support for deser. Use it to read and write JSON for any type that implements deser's Serialize and Deserialize.

use deser::{Deserialize, Serialize};

#[derive(Debug, Serialize, Deserialize)]
struct Event<'a> {
    // borrowed from the input, no allocation
    kind: &'a str,
    id: u128,
    payload: Vec<u8>,
}

let json = r#"{
    "kind": "upload",
    "id": 340282366920938463463374607431768211455,
    "payload": "aGVsbG8="
}"#;
let event: Event = deser_json::from_str(json).unwrap();
assert_eq!(event.kind, "upload");
assert_eq!(event.id, u128::MAX);
assert_eq!(event.payload, b"hello");

assert_eq!(
    deser_json::to_string(&event).unwrap(),
    concat!(
        r#"{"kind":"upload","#,
        r#""id":340282366920938463463374607431768211455,"#,
        r#""payload":"aGVsbG8="}"#,
    )
);

Why use it:

No dependencies besides deser by default. The speedups feature pulls in zmij and simdutf8 for faster float formatting and UTF-8 validation.
Borrowing: strings without escapes are passed on borrowed so types can hold &str pointing into the input.
Numbers without loss: 128 bit integers are written and read as numbers, and with DeserializerConfig::exact_numbers decimals such as 0.10 keep their exact text for types like rust_decimal::Decimal.
Bytes: Vec<u8> is base64 by default and can be configured per format or per field (hex, arrays of integers, ...).
Unlimited nesting: a million nested arrays do not overflow the stack.
JSON Lines: a Deserializer can read one value per line and recovers from errors in individual lines, a Serializer writes them.
Streams: from_reader and to_writer work with std::io, and the configurations read and write streams of values (JSON Lines or concatenated JSON) with deser::io or async runtimes (deser-tokio). Values are parsed while their input arrives, so only incomplete tokens are buffered, and written while they are serialized.
Source locations: errors carry line and column and with DeserializerConfig::track_locations values can be wrapped in deser_location::Spanned to learn where they came from.

deser-json 0.9.0

deser-json