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Quickstart

This page follows one input through the three most common interfaces: the command line, Rust and Python. Each produces the same value.

The input is a small settings file, settings.conf, that a person typed by hand:

// cache settings
name: 'cache'
ports: [8080, 8081,]
enabled: true

It has a comment, no outer braces, unquoted keys, a single-quoted string, a trailing comma and newlines instead of commas. A strict JSON parser rejects it at the first character.

On the command line

Prerequisite: the vexy-json binary is installed (see Installation).

  1. Parse the file:

    vexy-json settings.conf

    The result is pretty-printed JSON on standard output:

    {
  "name": "cache",
  "ports": [
    8080,
    8081
  ],
  "enabled": true
}

  2. Get the same value on one line with --compact:

    vexy-json --compact settings.conf

  3. Read from standard input instead of a file by leaving out the file name:

    printf "{a: 1, b: [2, 3,],}" | vexy-json -c

    {"a":1,"b":[2,3]}

Object keys are stored in a hash map, so the order of keys in the output can differ from the order in the input.

In Rust

Prerequisite: vexy-json is a dependency of your crate.

use vexy_json::parse;

fn main() -> vexy_json::Result<()> {
    let input = "// cache settings\nname: 'cache'\nports: [8080, 8081,]\nenabled: true";
    let value = parse(input)?;

    // Index objects with &str and arrays with usize.
    println!("{}", value["name"]);          // "cache"
    println!("{}", value["ports"][1]);      // 8081
    println!("{:?}", value["enabled"].as_bool()); // Some(true)
    Ok(())
}

parse returns vexy_json::Result<Value>. A missing key or index returns Value::Null instead of panicking. See Rust API.

In Python

Prerequisite: vexy-json is installed in your Python environment.

import vexy_json

text = "// cache settings\nname: 'cache'\nports: [8080, 8081,]\nenabled: true"
value = vexy_json.parse(text)

assert value == {"name": "cache", "ports": [8080, 8081], "enabled": True}

vexy_json.parse (also available as vexy_json.loads) returns plain Python dict, list, str, int, float, bool and None objects. Invalid input raises ValueError. See Python.

When input is rejected

Input that the parser cannot read raises an error with a byte position:

printf "{a: 1" | vexy-json

Error:
<stdin>: Expected , or } or newline but found Eof at position 5

The command exits with status 1. For input that was cut off in the middle, such as a truncated response from a language model, see Repairing incomplete input.

Next steps