NOTE: Jisoni is now integrated into the V standard library (vlib) as an experimental module. See the source code and documentation for more information. If you have issues or concerns regarding the use of the library, please file an issue into the V language repo instead.

JISONI

A work-in-progress JSON parser written on pure V. It aims to replace CJSON and provides a cleaner and simple-to-use API for encoding and decoding JSON.

API

module main

import jisoni
import http

fn main() {
    // Decoding
    resp := http.get('https://example.com')?

    // raw decode
    raw_person := jisoni.raw_decode(resp.text)?

    // decode to a type
    person2 := jisoni.decode<Person>(resp.text)?

    //Navigating
    person := raw_person.as_map()
    name := person['name'].as_str() // Bob
    age := person['age'].as_int() // 19
    pi := person['pi'].as_f() // 3.14.... 

    //Constructing an `Any` type
    mut me := map[string]jisoni.Any
    me['name'] = 'Ned Poolz'
    me['age'] = 18

    mut arr := []jisoni.Any{}
    arr << 'rock'
    arr << 'papers'
    arr << jisoni.null()
    arr << 12

    me['interests'] = arr

    mut pets := map[string]jisoni.Any
    pets['Sam'] = 'Maltese Shitzu' 
    me['pets'] = pets

    // Stringify to JSON
    println(me.str())
    //{"name":"Ned Poolz","age":18,"interests": ["rock", "papers", "scissors"],"pets":{"Sam":"Maltese"}}

    // Encode a struct/type to JSON
    encoded_json := jisoni.encode<Person>(person2)
}

Using decode<T> and encode<T>

In order to use the decode<T> and encode<T> function, you need to explicitly define two methods: from_json and to_json. from_json accepts a jisoni.Any argument and inside of it you need to map the fields you're going to put into the type. As for to_json method, you just need to map the values into jisoni.Any and turn it into a string.

struct Person {
mut:
    name string
    age  int = 20
    pets []string
}

fn (mut p Person) from_json(f Any) {
    obj := f.as_map()
    for k, v in obj {
        match k {
            'name' { p.name = v.as_str() }
            'age' { p.age = v.as_int() }
            'pets' { p.pets = v.as_arr().map(it.as_str()) }
            else {}
        }
    }
}

fn (p Person) to_json() string {
    mut obj := map[string]Any
    obj['name'] = p.name
    obj['age'] = p.age
    obj['pets'] = p.pets
    return obj.str()
}

fn main() {
    resp := os.read_file('./person.json')?
    person := jisoni.decode<Person>(resp)
    println(person) // Person{name: 'Bob', age: 28, pets: ['Floof']}
    person_json := jisoni.encode<Person>(person)
    println(person_json) // {"name": "Bob", "age": 28, "pets": ["Floof"]}
}

Using struct tags

Jisoni cannot use struct tags just like when you use the json module. However, it emits an Any type when decoding so it can be flexible on the way you use it.

Null Values

Jisoni have a null value for differentiating an undefined value and a null value. Use is for verifying the field you're using is a null.

fn (mut p Person) from_json(f Any) {
    obj := f.as_map()
    if obj['age'] is jisoni.Null {
        // use a default value
        p.age = 10
    }
}

Custom field names

In json, you can specify the field name you're mapping into the struct field by specifying a json: tag. In Jisoni, just simply cast the base field into a map (as_map()) and get the value of the field you wish to put into the struct/type.

fn (mut p Person) from_json(f jisoni.Any) {
    obj := f.as_map()
    p.name = obj['nickname'].as_str()
}

fn (mut p Person) to_json() string {
    obj := f.as_map()
    obj['nickname'] = p.name
    return obj.str()
}

Undefined Values

Getting undefined values has the same behavior as regular V types. If you're casting a base field into map[string]Any and fetch an undefined entry/value, it simply returns empty. As for the []Any, it returns an index error.

Casting a value to an incompatible type

Jisoni provides methods for turning Any types into usable types. The following list shows the possible outputs when casting a value to an incompatible type.

1. Casting non-array values as array (as_arr()) will return an array with the value as the content.
2. Casting non-map values as map (as_map()) will return a map with the value as the content.
3. Casting non-string values to string (as_str()) will return the stringified representation of the value.
4. Casting non-numeric values to int/float (as_int()/as_f()) will return zero.

TODO

• Function Organization
• JSON Tree Navigation
• Encoding
• Performance (Not an important issue for now)
• Testing (Especially on JSON Test Suite)
• Error Messages (adding line numbers to message is WIP)
• Parsing errors (Avoid correcting malformed/invalid ones!)

License

Licensed under MIT

Testing

Testing instructions will be updated soon.

Copyright

(c) 2020- Ned Palacios