index.js

var _ = require('lodash');

/**
 * Takes two objects and a callback. One schema object that contains nested
 * objects and functions, the other a paramater object with no constraints. The
 * schema object is traversed recursively and functions are evaluated in place
 * using the parameter object as the only parameter. The final evaluated object
 * is passed to the callback.
 * @param {Object} obj 
 * @param {Object} params 
 * @param {requestCallback} cb
 */
function mapSchema(obj, params, cb) {
    var mapValues;

    // Recursive functon to evaluate function objects
    // Omits any values of undefined or null
    mapValues = function(obj, params) {
        return _
            .chain(obj)
            .mapValues(function(val) {
                if(typeof(val) === 'function') {
                    return val(params);
                } else if(typeof(val) === 'object') {
                    return mapValues(val, params);
                } else {
                    return val;
                }
            })
            .omitBy(_.isUndefined)
            .omitBy(_.isNull)
            .value();
    };

    try {
        cb(mapValues(obj, params));
    } catch (ex) {
        cb(ex);
    }
}

module.exports = mapSchema;