conditional-expressions-json

Library for evaluating expressions in JSON data. Enables conditional section in your JSON data based on a provided context.

Example

{
    "House": {
        "Doors": 1,
        "Windows: "[$.windows]",
        "Basement": {
            "$if[$.basementRooms > 0]": {
                "Rooms": "[$.basementRooms]"
            }
        }
    }
}

import { applyConditionals } from 'conditional-expressions-json';

let data = JSON.parse(text);
let evaluated = applyConditionals(data, { windows: 4, basementRooms: 2 });
// {
//     "House": {
//         "Doors": 1,
//         "Windows": 4,
//         "Basement": {
//             "Rooms": 2
//         }
//     }
// }

See unit tests for more examples.

Expression language

The language is fairly simple:

1. Lazy logical operators && and ||
2. Comparison operators ==, !=, <, >, <=, >=
3. Function application f(e1, e2, ...)
4. Context access $.a.b[0]
5. Constants 12, 'Abc', true

Built-in functions:

• date(string) - converts a string into a date
• not(bool) - inverts a boolean value
• iff(bool, ifTrue, ifFalse) - lazy conditional function

Contributions welcome for more useful functions.