Underscore mixins for mongoose

gistfile1.js

_.mixin({
	filterByObject: function (arg, object) {
		var obj = {};
		for (var a in object) {
			if (typeof arg[a] == "object") {
				obj[a] = this.filterByObject(arg[a], object[a]);
			} else if (arg[a]) {
				obj[a] = arg[a];
			}
		}
		return obj;
	},
	filterByMongooseSchema: function (arg, schema) {
		return _.filterByObject(arg, schema.paths);
	},
	filterMongoosePrivates: function(doc) {
		var obj = {};
		var keys = _.reject(_.keys(doc._doc), function (key) { 
			return key.indexOf("_") === 0; 
		});
		for (var i=0,j=keys.length;i<j;i++) {
			obj[keys[i]] = doc[keys[i]];
		}
		return obj;
	},
	filterMongoosePrivatesArray: function(docs) {
		var arr = new Array();
		for (var i=0,j=docs.length;i<j;i++) {
			arr.push(_.filterMongoosePrivates(docs[i]));
		}
		return arr;
	}
});