Sexy isomorphic nodeJS function for instantiating any model with explicit fields (to prevent mass injection attacks) and a custom association with our User model. version 3

createInstanceWithFieldsAndConnection.js

"use strict";

/** @module createInstanceWithFieldsAndConnection */

var capitalizeFirstLetter = require("../utils/capitalizeFirstLetter");
var models = require("../wrapper").getSingleton();
var async = require("async");

/**
 * Isomorphic action for persisting an object or series of objects of model {{name}}, only accepting explicit fields, and
 * forming a connection between the new instance and the user who created it. Finally return using a
 * callback all the created models and model connections.
 *
 * @param params {object|Array} - object or objects to be instantiated and persisted
 * @param userInstance {object} - user model instance
 * @param name {string} - name of the model being created
 * @param {Array} [fields] - fields to be accepted when creating the models (defaults to allowing all fields)
 * @param callback {function} - callback function, returning the newly created instance and its connection to the user
 */

module.exports = function(params, userInstance, name, fields, callback){
    // function parameter validations, including making fields param entirely optional
    if (!callback || typeof callback !== "function") { throw new Error("Missing callback parameter"); }
    if (!params || typeof params !== "object") { throw new Error("Invalid params parameter"); }
    if (!userInstance || typeof userInstance !== "object") { throw new Error("Invalid userInstance parameter"); }
    if (!name || typeof name !== "string"){ throw new Error("Invalid name parameter"); }
    if (typeof fields === "function") { callback = fields; fields = null; }

    name = capitalizeFirstLetter(name); // ensure its uppercased to match our model definitions
    if (!(name in models)) { throw new Error("Model " + name + " is not defined"); }
    var modelKey = name + "Id"; // the key we will later use to build a connection

    // decide if we want to create one or create multiple
    var isMultiple = false;
    if (Array.isArray(params)) { isMultiple = true; }
    else { params = [params]; } // if singular, convert to array format for bulkCreate call

    // build the first query
    var options = {};
    if (fields && Array.isArray(fields)){ options.fields = fields; }

    var modelInstances;
    async.series({
        modelInstances: function(done){
            models[name].bulkCreate(params, options)
                .then(function(results){
                    modelInstances = results;
                    done(null, results);
                })
                .catch(function(err){
                    done(err);
                });
        },

        connections: function(done){
            var connections = [];
            // create a connection between the user and the single instance
            if (!isMultiple) {
                var params = {};
                params["UserId"] = userInstance.get('id');
                params[modelKey] = modelInstances[0].get('id');
                params["permissions"] = 70;
                connections.push(params);
            }
            // create a connection between the user and each instance
            else {
                modelInstances.forEach(function(modelInstance){
                    var params = {};
                    params["UserId"] = userInstance.get('id');
                    params[modelKey] = modelInstance.get('id');
                    params["permissions"] = 70;
                    connections.push(params);
                });
            }

            models.Connection.bulkCreate(connections)
                .then(function(connections){
                    done(null, connections);
                })
                .catch(function(err){
                    done(err);
                });
        }

    }, callback);
};