djng-urls.js

(function (angular, undefined) {
    'use strict';
    /*
     module: djng.urls
     Provide url reverse resolution functionality for django urls in angular
     Usage: djangoUrl.reverse(url_name, args_or_kwargs)

     Examples:
     - djangoUrl.reverse('home', [user_id: 2]);
     - djangoUrl.reverse('home', [2]);
     */
    var djngUrls = angular.module('djng.urls', []);

    djngUrls.provider('djangoUrl', function djangoUrlProvider() {
            var reverseUrl = '/angular/reverse/';

            this.setReverseUrl = function (url) {
                reverseUrl = url;
            };

            this.$get = function () {
                return new djangoUrl(reverseUrl);
            };
        }
    );

    var djangoUrl = function (reverseUrl) {
        /*
         Url-reversing service
         */

        //Functions from angular.js source, not public available
        //See: https://github.com/angular/angular.js/issues/7429
        function forEachSorted(obj, iterator, context) {
            var keys = sortedKeys(obj);
            for (var i = 0; i < keys.length; i++) {
                iterator.call(context, obj[keys[i]], keys[i]);
            }
            return keys;
        }

        function sortedKeys(obj) {
            var keys = [];
            for (var key in obj) {
                if (obj.hasOwnProperty(key)) {
                    keys.push(key);
                }
            }
            return keys.sort();
        }

        function buildUrl(url, params) {
            if (!params) return url;
            var parts = [];
            forEachSorted(params, function (value, key) {
                if (value === null || value === undefined) return;
                if (angular.isObject(value)) {
                    value = angular.toJson(value);
                }
                /*
                 If value is a string and starts with ':' we don't encode the value to enable parametrized urls
                 E.g. with .reverse('article',{id: ':id'} we build a url
                 /angular/reverse/?djng_url_name=article?id=:id, which angular resource can use
                 https://docs.angularjs.org/api/ngResource/service/$resource
                 */
                if ((typeof value === 'string' || value instanceof String) && value.lastIndexOf(':', 0) === 0) {
                    parts.push(encodeURIComponent(key) + '=' + value);
                } else {
                    parts.push(encodeURIComponent(key) + '=' + encodeURIComponent(value));
                }

            });
            return url + ((url.indexOf('?') === -1) ? '?' : '&') + parts.join('&');
        }

        // Service public interface
        this.reverse = function (url_name, args_or_kwargs) {
            var url = buildUrl(reverseUrl, {djng_url_name: url_name});
            /*
             Django wants arrays in query params encoded the following way: a = [1,2,3] -> ?a=1&a=2$a=3
             buildUrl function doesn't natively understand lists in params, so in case of a argument array
             it's called iteratively, adding a single parameter with each call

             url = buildUrl(url, {a:1}) -> returns /url?a=1
             url = buildUrl(url, {a:2}) -> returns /url?a=1&a=2
             ...
             */
            if (Array.isArray(args_or_kwargs)) {
                forEachSorted(args_or_kwargs, function (value) {
                    url = buildUrl(url, {'djng_url_args': value});
                });
                return url;
            }
            /*
             If there's a object of keyword arguments, a 'djng_url_kwarg_' prefix is prepended to each member
             Then we can directly call the buildUrl function
             */
            var params = {};
            forEachSorted(args_or_kwargs, function (value, key) {
                params['djng_url_kwarg_' + key] = value;
            });
            /*
             If params is empty (no kwargs passed) return url immediately
             Calling buildUrl with empty params object adds & or ? at the end of query string
             E.g. buldUrl('/url/djng_url_name=home', {}) -> /url/djng_url_name=home&
             */
            if (angular.equals(params, {})) { // If params is empty, no kwargs passed.
                return url;
            }
            return buildUrl(url, params);
        };
    };

})(window.angular);