Refactor rest dao to use promises

src/js/service/rest.js

@@ -39,7 +39,9 @@ ngModule.factory('oauthRestDao', function() {
 
 module.exports = RestDAO;
 
-function RestDAO() {}
+function RestDAO($q) {
+    this._q = $q;
+}
 
 /**
  * Set the REST DAO's base url
@@ -54,105 +56,107 @@ RestDAO.prototype.setBaseUri = function(baseUri) {
  * @param {String} options.uri URI relative to the base uri to perform the GET request with.
  * @param {String} options.type (optional) The type of data that you're expecting back from the server: json, xml, text. Default: json.
  */
-RestDAO.prototype.get = function(options, callback) {
+RestDAO.prototype.get = function(options) {
     options.method = 'GET';
-    this._processRequest(options, callback);
+    return this._processRequest(options);
 };
 
 /**
  * POST (create) request
  */
-RestDAO.prototype.post = function(item, uri, callback) {
-    this._processRequest({
+RestDAO.prototype.post = function(item, uri) {
+    return this._processRequest({
         method: 'POST',
         payload: item,
         uri: uri
-    }, callback);
+    });
 };
 
 /**
  * PUT (update) request
  */
-RestDAO.prototype.put = function(item, uri, callback) {
-    this._processRequest({
+RestDAO.prototype.put = function(item, uri) {
+    return this._processRequest({
         method: 'PUT',
         payload: item,
         uri: uri
-    }, callback);
+    });
 };
 
 /**
  * DELETE (remove) request
  */
-RestDAO.prototype.remove = function(uri, callback) {
-    this._processRequest({
+RestDAO.prototype.remove = function(uri) {
+    return this._processRequest({
         method: 'DELETE',
         uri: uri
-    }, callback);
+    });
 };
 
 //
 // helper functions
 //
 
-RestDAO.prototype._processRequest = function(options, callback) {
-    var xhr, format;
+RestDAO.prototype._processRequest = function(options) {
+    return this._q(function(resolve, reject) {
+        var xhr, format;
 
-    if (typeof options.uri === 'undefined') {
-        callback({
-            code: 400,
-            errMsg: 'Bad Request! URI is a mandatory parameter.'
-        });
-        return;
-    }
-
-    options.type = options.type || 'json';
-
-    if (options.type === 'json') {
-        format = 'application/json';
-    } else if (options.type === 'xml') {
-        format = 'application/xml';
-    } else if (options.type === 'text') {
-        format = 'text/plain';
-    } else {
-        callback({
-            code: 400,
-            errMsg: 'Bad Request! Unhandled data type.'
-        });
-        return;
-    }
-
-    xhr = new XMLHttpRequest();
-    xhr.open(options.method, this._baseUri + options.uri);
-    xhr.setRequestHeader('Accept', format);
-    xhr.setRequestHeader('Content-Type', format);
-
-    xhr.onload = function() {
-        var res;
-
-        if (xhr.readyState === 4 && (xhr.status === 200 || xhr.status === 201 || xhr.status === 304)) {
-            if (options.type === 'json') {
-                res = xhr.responseText ? JSON.parse(xhr.responseText) : xhr.responseText;
-            } else {
-                res = xhr.responseText;
-            }
-
-            callback(null, res, xhr.status);
+        if (typeof options.uri === 'undefined') {
+            reject({
+                code: 400,
+                message: 'Bad Request! URI is a mandatory parameter.'
+            });
             return;
         }
 
-        callback({
-            code: xhr.status,
-            errMsg: xhr.statusText
-        });
-    };
+        options.type = options.type || 'json';
 
-    xhr.onerror = function() {
-        callback({
-            code: 42,
-            errMsg: 'Error calling ' + options.method + ' on ' + options.uri
-        });
-    };
+        if (options.type === 'json') {
+            format = 'application/json';
+        } else if (options.type === 'xml') {
+            format = 'application/xml';
+        } else if (options.type === 'text') {
+            format = 'text/plain';
+        } else {
+            reject({
+                code: 400,
+                message: 'Bad Request! Unhandled data type.'
+            });
+            return;
+        }
 
-    xhr.send(options.payload ? JSON.stringify(options.payload) : undefined);
+        xhr = new XMLHttpRequest();
+        xhr.open(options.method, this._baseUri + options.uri);
+        xhr.setRequestHeader('Accept', format);
+        xhr.setRequestHeader('Content-Type', format);
+
+        xhr.onload = function() {
+            var res;
+
+            if (xhr.readyState === 4 && (xhr.status === 200 || xhr.status === 201 || xhr.status === 304)) {
+                if (options.type === 'json') {
+                    res = xhr.responseText ? JSON.parse(xhr.responseText) : xhr.responseText;
+                } else {
+                    res = xhr.responseText;
+                }
+
+                resolve(res, xhr.status);
+                return;
+            }
+
+            reject({
+                code: xhr.status,
+                message: xhr.statusText
+            });
+        };
+
+        xhr.onerror = function() {
+            reject({
+                code: 42,
+                message: 'Error calling ' + options.method + ' on ' + options.uri
+            });
+        };
+
+        xhr.send(options.payload ? JSON.stringify(options.payload) : undefined);
+    });
 };