serde-kv

serde-kv is a serde data format implementation for a basic key/value string.

The format is a space-separated list of key=value pairs. Values are bare tokens, or double-quoted when they contain spaces or special characters:

foo=bar baz=42 cool=true message="hello world"

There is no type inference at the format level — the type comes from the target struct field. A raw token like 42 becomes the string "42" for a String field, or the integer 42 for a u64 field. Quotes are purely for parsing, so foo=42 and foo="42" decode to the same value.

Example

use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize, PartialEq, Debug)]
struct Record {
    foo: String,
    baz: u64,
    cool: bool,
    message: String,
}

fn main() {
    let line = r#"foo=bar baz=42 cool=true message="hello world""#;

    // Deserialize a line into a struct.
    let record: Record = serde_kv::from_str(line).unwrap();
    assert_eq!(record.baz, 42);
    assert_eq!(record.message, "hello world");

    // Serialize it back to a line.
    let out = serde_kv::to_string(&record).unwrap();
    assert_eq!(out, line);
}

You can also deserialize into a map, where every value is a string:

use std::collections::HashMap;

let map: HashMap<String, String> =
    serde_kv::from_str(r#"foo=bar baz=42 msg="hello world""#).unwrap();
assert_eq!(map["baz"], "42");

Supported types

• Flat scalars: String, all integer/float widths, bool, char.
• Option<T>: a missing key deserializes to None; None is skipped when serializing.
• Unknown keys are ignored, or collected with #[serde(flatten)] extra: HashMap<String, String>.

Nested structs and sequences are not supported.