feat: Optionally reject on null lookup

This is a backwards-compatible way of allowing rejection if the value of
the getItem lookup is null. If you actually want to store and retrieve
null as a value, just use the single arity version of `getItem`.

Fixes #111

src/angular-localForage.js

@@ -138,7 +138,7 @@
       };
 
       // Directly get a value from storage
-      LocalForageInstance.prototype.getItem = function getItem(key) {
+      LocalForageInstance.prototype.getItem = function getItem(key, rejectOnNull) {
         // throw error on undefined key
         if(angular.isUndefined(key)) {
           throw new Error("You must define a key to get");
@@ -162,16 +162,26 @@
               return res;
             }
           }).then(function() {
+            var shouldResolve = true;
             for (var i = 0; i < key.length; i++) {
               if (angular.isUndefined(res[i])) {
                 res[i] = null;
+                shouldResolve = false;
               }
             }
-            deferred.resolve(res);
+            if (shouldResolve || !rejectOnNull) {
+              deferred.resolve(res);
+            } else {
+              deferred.reject(res);
+            }
           });
         } else {
           promise = self._localforage.getItem(self.prefix() + key).then(function(item) {
-            deferred.resolve(item);
+            if (rejectOnNull && item === null) {
+              deferred.reject(item);
+            } else {
+              deferred.resolve(item);
+            }
           });
         }
 

tests/angular-localForage.js

@@ -71,6 +71,17 @@ describe('Module: LocalForageModule', function() {
     }, done);
   });
 
+  it('getItem produces a rejected promise for unknown key if second parameter is true', function(done) {
+    var interval = triggerDigests();
+
+    $localForage.getItem('this key is unknown', true)
+      .catch(function(err) {
+        stopDigests(interval);
+        expect(err).toBe(null);
+        done();
+      });
+  })
+
   describe('getItem for an array with unknown keys', function() {
     it('should produce null values with all unknown keys', function(done) {
       var interval = triggerDigests();
@@ -175,16 +186,30 @@ describe('Module: LocalForageModule', function() {
     $localForage.setItem(['myName', 'myPassion', 'myHobbie'], values).then(function(data) {
       expect(data).toEqual(values);
 
-      $localForage.getItem(['myHobbie', 'myName']).then(function(data) {
+        $localForage.getItem(['myHobbie', 'myName', 'notInDatabase']).then(function(data) {
         stopDigests(interval);
-        expect(data.length).toEqual(2);
-        expect(data).toEqual(['Open Source', 'Olivier Combe']);
+        expect(data.length).toEqual(3);
+        expect(data).toEqual(['Open Source', 'Olivier Combe', null]);
         done();
       }, done);
 
     }, done);
   });
 
+  it('getItem should reject if one of the values is null if true is passed as the second argument', function(done) {
+    var interval = triggerDigests();
+
+    $localForage.setItem(['myName', 'myPassion'], ['Scott Trinh', 'Anarchy']).then(function(data) {
+      $localForage.getItem(['myPassion', 'myName', 'notInDatabase'], true).catch(function(data) {
+        stopDigests(interval);
+        expect(data.length).toEqual(3);
+        expect(data).toEqual(['Anarchy', 'Scott Trinh', null]);
+        done();
+      });
+    });
+
+  })
+
   it('iterate should be defined', function() {
     expect($localForage.iterate).toBeDefined();
     expect(typeof $localForage.iterate).toBe('function');