Fix incremental upgrade problem.

Author: Ronald Maravilla

README.md

@@ -49,7 +49,25 @@ angular.module('myModuleName', ['xc.indexedDB'])
 ```
 The connection method takes the databasename as parameter,
 the upgradeCallback has 3 parameters:
-function callback(event, database, transaction). For upgrading your db structure, see 
+function callback(event, database, transaction). AngularJS-indexedDB supports incremental
+upgrades.  Simply define what to do for each version incrementally:
+```javascript
+angular.module('myModuleName', ['xc.indexedDB'])
+  .config(function ($indexedDBProvider) {
+    $indexedDBProvider
+      .connection('myIndexedDB')
+      .upgradeDatabase(1, function(event, db, tx){
+        var objStore = db.createObjectStore('people', {keyPath: 'ssn'});
+        objStore.createIndex('name_idx', 'name', {unique: false});
+        objStore.createIndex('age_idx', 'age', {unique: false});
+      });
+      .upgradeDatabase(2, function(event, db, tx){
+        db.createObjectStore('peoplePhones', {keyPath: 'person_ssn'});
+      });
+  });
+```
+When upgrade is required only the migrations which have not been run yet will be run.
+For upgrading your db structure, see 
 https://developer.mozilla.org/en-US/docs/IndexedDB/Using_IndexedDB.
 
 You can also define your own error handlers, overwriting the default ones, which log to console.

src/indexeddb.js

@@ -27,6 +27,7 @@ angular.module('xc.indexedDB', []).provider('$indexedDB', function() {
     module.db = null;
     module.dbPromise = null;
     module.outStandingTransactionCount = 0;
+    module.upgradesByVersion = {}
 
     /** predefined callback functions, can be customized in angular.config */
     module.onTransactionComplete = function(e) {
@@ -76,8 +77,8 @@ angular.module('xc.indexedDB', []).provider('$indexedDB', function() {
      * @returns {object} this
      */
     module.upgradeDatabase = function(newVersion, callback) {
-        module.dbVersion = newVersion;
-        module.upgradeCallback = callback;
+        module.upgradesByVersion[newVersion] = callback;
+        module.dbVersion = Math.max.apply(null, Object.keys(module.upgradesByVersion) )
         return this;
     };
 
@@ -91,6 +92,16 @@ angular.module('xc.indexedDB', []).provider('$indexedDB', function() {
             }
         };
     };
+    
+    var applyNeededUpgrades = function(oldVersion, event, db, tx) {
+      for(var version in module.upgradesByVersion) {
+        if( !module.upgradesByVersion.hasOwnProperty(version) || version <= oldVersion ) {
+          continue;
+        }
+        console.log("Running upgrade : " + version + " from " + oldVersion);
+        module.upgradesByVersion[version](event , db, tx)
+      }
+    };
 
     module.$get = ['$q', '$rootScope', function($q, $rootScope) {
         /**
@@ -138,7 +149,7 @@ angular.module('xc.indexedDB', []).provider('$indexedDB', function() {
                     var db = e.target.result, tx = e.target.transaction;
                     console.log('upgrading database "' + db.name + '" from version ' + e.oldVersion+
                         ' to version ' + e.newVersion + '...');
-                    module.upgradeCallback && module.upgradeCallback(e, db, tx);
+                    applyNeededUpgrades(e.oldVersion, e, db, tx);
                 };
             }