Crate json [] [src]

json-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.

let parsed = json::parse(r#"

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

"#).unwrap();

let instantiated = object!{
    "code" => 200,
    "success" => true,
    "payload" => object!{
        "features" => array![
            "awesome",
            "easyAPI",
            "lowLearningCurve"
        ]
    }
};

assert_eq!(parsed, instantiated);

First class citizen

Using macros and indexing, it's easy to work with the data.

let mut data = object!{
    "foo" => false,
    "bar" => json::Null,
    "answer" => 42,
    "list" => array![json::Null, "world", true]
};

// Partial equality is implemented for most raw types:
assert!(data["foo"] == false);

// And it's type aware, `null` and `false` are different values:
assert!(data["bar"] != false);

// But you can use any Rust number types:
assert!(data["answer"] == 42);
assert!(data["answer"] == 42.0);
assert!(data["answer"] == 42isize);

// Access nested structures, arrays and objects:
assert!(data["list"][0].is_null());
assert!(data["list"][1] == "world");
assert!(data["list"][2] == true);

// Error resilient - accessing properties that don't exist yield null:
assert!(data["this"]["does"]["not"]["exist"].is_null());

// Mutate by assigning:
data["list"][0] = "Hello".into();

// Use the `dump` method to serialize the data:
assert_eq!(data.dump(), r#"{"answer":42,"bar":null,"foo":false,"list":["Hello","world",true]}"#);

// Or pretty print it out:
println!("{:#}", data);

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!(data.dump(), r#"[10,"foo",false]"#);

Putting fields on objects:

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

data["answer"] = 42.into();
data["foo"] = "bar".into();

assert_eq!(data.dump(), r#"{"answer":42,"foo":"bar"}"#);

array! macro:

let data = array!["foo", "bar", 100, true, json::Null];
assert_eq!(data.dump(), r#"["foo","bar",100,true,null]"#);

object! macro:

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

Reexports

pub use value::JsonValue::Null;

Modules

iterators

Macros

array!
object!

Enums

JsonError
JsonValue

Functions

from

Convenience for JsonValue::from(value)

parse
stringify

Pretty prints out the value as JSON string.

stringify_pretty

Pretty prints out the value as JSON string. Second argument is a number of spaces to indent new blocks with.

Type Definitions

Array
JsonResult
Object