jqesque

A Rust library to parse simplified JSON assignments in a jq-like syntax and convert them into JSON structures.

Sometimes you want to express simplified JSON assignments as strings without writing the full JSON syntax. This library borrows syntax from jq and JSONPath to create a simplified way to represent JSON assignments.

Features

• Nested Objects: Supports nested objects (e.g., foo.bar.baz=true).
• Arrays with Indices: Supports arrays with indices (e.g., foo[0].bar=zoot, where the index must be a positive number).
• Boolean, Number, and Null Values: Automatically parses values as booleans, numbers, or null if possible. By default, the value is a string unless serde can parse it as a boolean, number, or null.
• Custom Separators: Scopes can be separated by Separator::Dot (.), Separator::Slash (/), or Separator::Custom(char) (custom character).

Values can be anything that serde_json can parse, including strings, numbers, booleans, null, objects, and arrays.

Examples

Basic Usage

use jqesque::Jqesque;
use serde_json::json;

fn main() {
    let input = "foo.bar[0].baz=hello";
    let jqesque = input.parse::<Jqesque>().unwrap();
    // Without using turbofish syntax:
    // let jqesque: Jqesque = input.parse().unwrap();

    // Alternatively, if you want to specify the separator:
    // let jqesque = Jqesque::from_str_with_separator(input, Separator::Dot).unwrap();

    let json_output = jqesque.as_json();
    assert_eq!(json_output, json!({
        "foo": {
            "bar": [
                {
                    "baz": "hello"
                }
            ]
        }
    }));
}

Specifying the separator

use jqesque::{Jqesque, Separator};
use serde_json::json;

fn main() {
    let input = "foo/bar[0]/baz=true";
    let jqesque = Jqesque::from_str_with_separator(input, Separator::Slash).unwrap();

    let json_output = jqesque.as_json();
    assert_eq!(json_output, json!({
        "foo": {
            "bar": [
                {
                    "baz": true
                }
            ]
        }
    }));
}

Inserting into an existing JSON structure

use serde_json::json;
use jqesque::{Jqesque, Separator};

let mut json_obj = json!({
    "settings": {
        "theme": {
            "color": "red",
            "font": "Arial",
            "size": 12
        }
    }
});

let input = "settings.theme={\"color\":\"blue\",\"font\":\"Helvetica\"}";
let jqesque = Jqesque::from_str_with_separator(input, Separator::Dot).unwrap();

jqesque.insert_into(&mut json_obj);

let expected = json!({
    "settings": {
        "theme": {
            "color": "blue",
            "font": "Helvetica"
        }
    }
});

assert_eq!(json_obj, expected);
// Note that the "size" key in the original "theme" object is removed.

Merging into an existing JSON structure

use serde_json::json;
use jqesque::{Jqesque, Separator};

let mut json_obj = json!({
    "settings": {
        "theme": {
            "color": "red",
            "font": "Arial",
            "size": 12
        }
    }
});

let input = "settings.theme={\"color\":\"blue\",\"font\":\"Helvetica\"}";
let jqesque = Jqesque::from_str_with_separator(input, Separator::Dot).unwrap();

jqesque.merge_into(&mut json_obj);

let expected = json!({
    "settings": {
        "theme": {
            "color": "blue",
            "font": "Helvetica",
            "size": 12
        }
    }
});

assert_eq!(json_obj, expected);
// Note that the "size" key in the original "theme" object is preserved.

License

See the LICENSE file for details.