GeddyJs belongsToMany with Array helper

belongsToMany.js

/*
 * GeddyJs belongsToMany helper module
 * Ivan Seidel Gomes ([email protected])
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 

	Creates a geddy association between thisModel and thatModel.

	Examples (inside model declaration):
		belongsToMany(this, 'Photos');

	With options:
		// User model
		belongsToMany(this, 'Users', {
			as: 'Friendships',
			otherKey: 'facebookId',
		});

		// Photo model
		belongsToMany(this, 'Users');

		// Coach
		belongsToMany(this, 'Teams', {
			as: 'CoachedTeams'
		});

*/

var _ = require('lodash');
var inflection = geddy.inflection;

var belongsToMany = function (model, thatModel, opts) {
	opts = _.defaults(opts || {}, {
		as: thatModel,
		otherKey: 'id',
	});

	// Other Model name
	var thatModelName = inflection.singularize(thatModel);

	// Key used in this model to store ids
	var thisNameSingular = inflection.singularize(opts.as);
	var thisNamePlural = inflection.pluralize(opts.as);

	// Key used in this model to save array
	var thisKeyName = thisNameSingular.toLowerCase() + 'Ids';

	// Setup property
	model.property(thisKeyName, 'object');

	// Extract ids from model list
	function pluckSmart(models, key){
		var modelIds = [];
		for(var k in models){
			var checkModel = models[k];

			// If is an object, extract the id from it
			if(!checkModel){
				// Skip. It's empty/null/0
			}else if(_.isObject(checkModel)){
				// Id is stored in `otherKey` field
				modelIds.push(checkModel[key]);
			}else{
				// Push it. Should be the id...
				modelIds.push(checkModel);
			}
		}
		return modelIds;
	}

	// Get model method name (this side)
	var getModels = 'get'+thisNamePlural;
	model[getModels] = function (next){
		
		var modelIds = this[thisKeyName] || [];

		// If next is assigned, we associate and fetch models
		if(_.isFunction(next)){
			if(!modelIds){
				// Nothing. Just callback
				next(null, []);
			}else{
				// Find Model and create Query
				var otherModel = geddy.model[thatModelName];
				if(!otherModel) throw new Error('Model '+thatModelName+' not found');

				var query = {};
				query[opts.otherKey] = modelIds;

				// Query it
				otherModel.all(query, next);
			}
		}

		// Returns data (already loaded in model)
		return modelIds;
	};


	var removeModels = 'remove'+thisNamePlural;
	model[removeModels] = function (models){
		if(!models) models = [];
		if(!_.isArray(models)) models = [models];

		// Get Current ids in this model property
		var modelIds = pluckSmart(models, opts.otherKey);

		// Now we have a list of ids. Let's find and remove it:
		var newIds = _.difference(this[thisKeyName], modelIds);

		// Set to model
		var newProps = {};
		newProps[thisKeyName] = newIds;
		this.updateProperties(modelIds);

		// Return filteded Ids
		return newIds;
	};

	var addModel = 'add'+thisNameSingular;
	var addModels = 'add'+thisNamePlural;
	model[addModel] = model[addModels] = function (models){
		if(!models) models = [];
		if(!_.isArray(models)) models = [models];

		// Get Current ids in this model property
		var modelIds = pluckSmart(models, opts.otherKey);

		// Now we have a list of ids. Let's find and remove it:
		var newIds = _.union(this[thisKeyName], modelIds);

		// Set to model
		var newProps = {};
		newProps[thisKeyName] = newIds;
		this.updateProperties(newProps);

		// Return filteded Ids
		return newIds;
	}

}

module.exports = belongsToMany;