#json #macro #native #array

macro native-json-macro

Native JSON for Rust

2 stable releases

Uses new Rust 2021

1.0.1 Nov 24, 2022

#395 in Procedural macros

Download history 78/week @ 2022-11-23 11/week @ 2022-11-30

89 downloads per month
Used in 2 crates (via native-json)

MIT license

24KB
449 lines

Native JSON for Rust

This crate provides native JSON syntax for Rust, it brings with a powerful way of parsing JSON syntax into native Rust structs. You can declare the JSON object natively as you do with JavaScript, JSON in Rust was made easy!

Note: This crate is just a crude proc-macro (compiler plugin), for more features, please refer to native-json

Usage

Add dependencies to your Cargo.toml, serde_json is only needed if you want to stringify the JSON object.

[dependencies]
native-json = "1.1"
serde = {version = "1.0", features = ["derive"] }
serde_json = "1.0"

Example of using native JSON object

use native_json::json;
use std::collections::HashMap;
use serde::{Deserialize, Serialize};

fn main()
{
    let mut json = json!{
        name: "native json",
        style: {
            color: "red",
            size: 12,
            bold: true,
            range: null
        },
        array: [5,4,3,2,1],
        vector: vec![1,2,3,4,5],
        hashmap: HashMap::from([ ("a", 1), ("b", 2), ("c", 3) ]);,
        students: [
            {name: "John", age: 18},
            {name: "Jack", age: 21},
        ],
    };

    // Native access
    json.style.size += 1;
    json.students[0].age += 2;

    // Debug
    println!("{:#?}", t);

    // Stringify
    let text = serde_json::to_string_pretty(&json).unwrap();
    println!("{}", text);
}

Declare a named JSON struct

With JSON decalre syntax, you can declare nested native JSON object in place.

JSON Declare Syntax

json!{
JSON_OBJECT_NAME { 
    name : type, 
    array: [type],
    object: {
        name: type,
        ...
    },
    ...
}}

The native-json will generate native Rust structs for you, each object is named by object hierarchy path, concatenated with underscore.

  1. JSON_OBJECT_NAME.object was converted to JSON_OBJECT_NAME_object
  2. JSON_OBJECT_NAME.array's item was converted to JSON_OBJECT_NAME_array_item

Example of using named JSON object

use native_json::json;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;

json!{ School {
    name: String,
    students: [
        { name: String, age: u16 },
        ...
    ],
    map: HashMap<String, String>,
    nullable: Option<String>
}}

fn main()
{
    let mut school = School::new();

    school.name = "MIT".to_string();
    school.map.insert("Tom".to_owned(), "Profile".to_owned());

    // using initializer
    let mut john = School_students_item::new();
    john.name = "John".to_owned();
    john.age = 18;
    school.students.push(john);

    // using struct
    let jack = School_students_item { name: "Jack".to_string(), age: 21 };
    school.students.push(jack);

    // show
    println!("{:#?}", school);
}

Dependencies

~200–580KB
~14K SLoC