map-obj

Map over the keys and values of a JSON object.

Transform the keys and/or values of a serde_json::Value object with a closure, optionally recursing into nested objects and arrays. A faithful Rust port of the widely-used map-obj npm package — the building block behind key transforms like camelcase-keys.

• deep recursion (into nested objects and objects within arrays)
• Skip entries, rename keys, transform values, or stop recursion per entry
• __proto__ keys are dropped
• Differential-tested against the reference map-obj implementation (60k cases)

Install

[dependencies]
map-obj = "0.1"
serde_json = "1"

Usage

use serde_json::json;
use map_obj::{map_obj, MapEntry};

// Rename keys:
let upper = map_obj(&json!({ "a": 1, "b": 2 }), false, |key, value| {
    MapEntry::keep(key.to_uppercase(), value.clone())
});
assert_eq!(upper, json!({ "A": 1, "B": 2 }));

// Recurse with `deep`, transform values, and drop some entries:
let result = map_obj(&json!({ "keep": { "n": 2 }, "drop": 9 }), true, |key, value| {
    if key == "drop" {
        MapEntry::Skip
    } else if let Some(n) = value.as_i64() {
        MapEntry::keep(key, json!(n * 10))
    } else {
        MapEntry::keep(key, value.clone())
    }
});
assert_eq!(result, json!({ "keep": { "n": 20 } }));

Use [MapEntry::keep_without_recursing] to keep an entry but not descend into its value.

Contributors ✨

This project follows the all-contributors specification. Contributions of any kind are welcome — code, docs, bug reports, ideas, reviews! See the emoji key for how each contribution is recognized, and open a PR or issue to get involved.

Thanks goes to these wonderful people:

License

Licensed under either of MIT or Apache-2.0 at your option.