schema.js

import {get, set, each, isObject, isArray, isFunction, cloneDeep} from "lodash";

// Create a new model by schema default values
module.exports.createDefaultObject = function (schema, obj = {}){
	each(schema.fields, (field) => {
		if (get(obj, field.model) === undefined && field.default !== undefined) {
			if (isFunction(field.default)) {
				set(obj, field.model, field.default(field, schema, obj));
			} else if (isObject(field.default) || isArray(field.default)) {
				set(obj, field.model, cloneDeep(field.default));
			} else
				set(obj, field.model, field.default);
		}
	});
	return obj;
};

// Get a new model which contains only properties of multi-edit fields
module.exports.getMultipleFields = function(schema) {
	let res = [];
	each(schema.fields, (field) => {
		if (field.multi === true) 
			res.push(field);
	});

	return res;
};

// Merge many models to one 'work model' by schema
module.exports.mergeMultiObjectFields = function(schema, objs) {
	let model = {};

	let fields = module.exports.getMultipleFields(schema);

	each(fields, (field) => {
		let mergedValue = undefined;
		let notSet = true;
		let path = field.model;

		each(objs, (obj) => {
			let v = get(obj, path);
			if (notSet) {
				mergedValue = v;
				notSet = false;
			}
			else if (mergedValue != v) {
				mergedValue = undefined;
			}
		});

		set(model, path, mergedValue);
	});

	return model;
};

module.exports.slugifyFormID = function(schema, prefix = "") {
	// Try to get a reasonable default id from the schema,
	// then slugify it.
	if (typeof schema.id !== "undefined") {
		// If an ID's been explicitly set, use it unchanged
		return prefix + schema.id;
	} else {
		// Return the slugified version of either:
		return prefix + (schema.inputName || schema.label || schema.model)
		// NB: This is a very simple, conservative, slugify function,
		// avoiding extra dependencies.
		.toString()
		.trim()
		.toLowerCase()
		// Spaces & underscores to dashes
		.replace(/ |_/g, "-")
		// Multiple dashes to one
		.replace(/-{2,}/g, "-")
		// Remove leading & trailing dashes
		.replace(/^-+|-+$/g, "")
		// Remove anything that isn't a (English/ASCII) letter, number or dash.
		.replace(/([^a-zA-Z0-9-]+)/g, "")
		;
	}
};