Crate json [−] [src]

🦄 JSON in Rust

Parse and serialize JSON with ease.

Complete Documentation - Cargo - Repository

Why?

JSON is a very loose format where anything goes - arrays can hold mixed types, object keys can change types between API calls or not include some keys under some conditions. Mapping that to idiomatic Rust structs introduces friction.

This crate intends to avoid that friction by using extensive static dispatch and hiding type information behind enums, while still giving you all the safety guarantees of safe Rust code.

let data = json::parse("

{
    \"code\": 200,
    \"success\": true,
    \"payload\": {
        \"features\": [
            \"awesome\",
            \"easyAPI\",
            \"lowLearningCurve\"
        ]
    }
}

").unwrap();

assert!(data["code"].is(200));
assert!(data["success"].is(true));
assert!(data["payload"]["features"].is_array());
assert!(data["payload"]["features"][0].is("awesome"));
assert!(data["payload"]["features"].contains("easyAPI"));

// Error resilient: non-existent values default to null
assert!(data["this"]["does"]["not"]["exist"].is_null());

Easily create JSON data without defining structs

#[macro_use]
extern crate json;

fn main() {
    let data = object!{
        "a" => "bar",
        "b" => array![1, false, "foo"]
    };

    assert_eq!(json::stringify(data), "{\"a\":\"bar\",\"b\":[1,false,\"foo\"]}");
}

Serialize with `json::stringify(value)`

Primitives:

// str slices
assert_eq!(json::stringify("foobar"), "\"foobar\"");

// Owned strings
assert_eq!(json::stringify("foobar".to_string()), "\"foobar\"");

// Any number types
assert_eq!(json::stringify(42), "42");

// Booleans
assert_eq!(json::stringify(true), "true");
assert_eq!(json::stringify(false), "false");

Explicit null type json::Null:

assert_eq!(json::stringify(json::Null), "null");

Optional types:

let value: Option<String> = Some("foo".to_string());
assert_eq!(json::stringify(value), "\"foo\"");

let no_value: Option<String> = None;
assert_eq!(json::stringify(no_value), "null");

Vector:

let data = vec![1,2,3];
assert_eq!(json::stringify(data), "[1,2,3]");

Vector with optional values:

let data = vec![Some(1), None, Some(2), None, Some(3)];
assert_eq!(json::stringify(data), "[1,null,2,null,3]");

Pushing to arrays:

let mut data = json::JsonValue::new_array();

data.push(10);
data.push("foo");
data.push(false);

assert_eq!(json::stringify(data), "[10,\"foo\",false]");

Putting fields on objects:

let mut data = json::JsonValue::new_object();

data.put("answer", 42);
data.put("foo", "bar");

assert_eq!(json::stringify(data), "{\"answer\":42,\"foo\":\"bar\"}");

array! macro:

let data = array!["foo", "bar", 100, true, json::Null];
assert_eq!(json::stringify(data), "[\"foo\",\"bar\",100,true,null]");

object! macro:

let data = object!{
    "name"    => "John Doe",
    "age"     => 30,
    "canJSON" => true
};
assert_eq!(
    json::stringify(data),
    // Because object is internally using a BTreeMap,
    // the key order is alphabetical
    "{\"age\":30,\"canJSON\":true,\"name\":\"John Doe\"}"
);

Reexports

pub use value::JsonValue::Null;

Macros

array!
object!

Enums

JsonError
JsonValue

Functions

parse
stringify
stringify_ref

Type Definitions

Array
JsonResult
Object