json-sharp

json-sharp

Process operations on pure JSON objects.

How it works

JSONSharp.process clones an object and processes operations returning a modified object.

Operations are simple objects with a single property representing its name.

The operation name should be preceded by the # (sharp) symbol to avoid conflicts with real data.

The property value is processed by the operation logic using a given context.

Motivation

Some systems need slightly different configuration between environments and contexts. This technique allows to have a good degree of reuse with a simple format.

Example

Given the following object and context:

var config = {
    '#merge': [
        {debug: true, url: 'http://localhost'},
        {
            '#switch': {
                '#property': 'env',
                '#case': {
                    dev: {
                        url: 'http://dev.com/'
                    },
                    prod: {
                        url: 'http://prod.com/',
                        debug: false
                    }
                }
            }
        }
    ]
};

var context = {
    env: 'dev'
};

var devConfig = require('JSONSharp').process(config, context);

Results in the following devConfig object:

{
    debug: true, // Debug flag inherited from merging with the defaults
    url: 'http://dev.com/' // Url is replaced
}

Operations

#merge

The #merge operation takes a list of objects and deeply merges its properties using the deepmerge library.

Examples:

JSONSharp.process({'#merge': [{a: 'a'}, {b: 'b']}, {});
// ==> {a: 'a', b: 'b'}

#switch

The #switch operation works much like the switch Javascript statement, with the exception that it doesn't use a break statement.

It takes an object with the following properties:

• #property: the property name or JSONPath to be matched for results
• #case: an object mapping #property values to desired results
• #case.#default: the value will be used if no matching value is found

Examples:

var switchObj = {
    '#switch': {
        '#property': 'name',
        '#case': {a: 'Prop A', '#default': 'not found'}
    }
};

JSONSharp.process(switchObj, {});
// ==> "not found"

JSONSharp.process(switchObj, {name: 'a'});
// ==> "Prop A"

JSONSharp.process(switchObj, {name: '$.a'});
// ==> "Prop A"

Property resolution

A #property starting with $. will be resolved using the JSONPath library, otherwise simple property access will be used.