loopback-datasource-juggler/lib/introspection.js

module.exports = function getIntrospector(ModelBuilder) {

    function introspectType(value) {

        // Unknown type, using Any
        if (value === null || value === undefined) {
            return ModelBuilder.Any;
        }

        // Check registered schemaTypes
        for (var t in ModelBuilder.schemaTypes) {
            var st = ModelBuilder.schemaTypes[t];
            if (st !== Object && st !== Array && (value instanceof st)) {
                return t;
            }
        }

        var type = typeof value;
        if (type === 'string' || type === 'number' || type === 'boolean') {
            return type;
        }

        if (value instanceof Date) {
            return 'date';
        }

        if (Array.isArray(value)) {
            for (var i = 0; i < value.length; i++) {
                if (value[i] === null || value[i] === undefined) {
                    continue;
                }
                var itemType = introspectType(value[i]);
                if (itemType) {
                    return [itemType];
                }
            }
            return 'array';
        }

        if (type === 'function') {
            return value.constructor.name;
        }

        var properties = {};
        for (var p in value) {
            var itemType = introspectType(value[p]);
            if (itemType) {
                properties[p] = itemType;
            }
        }
        if (Object.keys(properties).length === 0) {
            return 'object';
        }
        return properties;
    }

    return introspectType;
}