Datasnapshot exists() #1094

Author: EddyVerbruggen

demo/app/main-view-model.ts

@@ -237,6 +237,7 @@ export class HelloWorldModel extends Observable {
           okButtonText: "Darn!"
         });
       } else {
+        console.log("key exists? " + result.exists());
         this.set("path", path);
         this.set("key", result.key);
         this.set("value", JSON.stringify(result.val()));
@@ -256,6 +257,7 @@ export class HelloWorldModel extends Observable {
     firebaseWebApi.database().ref(path)
         .once("value")
         .then(result => {
+          console.log("key exists? " + result.exists());
           this.set("path", path);
           this.set("key", result.key);
           this.set("value", JSON.stringify(result.val()));
@@ -268,6 +270,7 @@ export class HelloWorldModel extends Observable {
     firebaseWebApi.database().ref(path)
         .once("value")
         .then(result => {
+          console.log("key exists? " + result.exists());
           this.set("path", path);
           this.set("key", result.key);
           this.set("value", JSON.stringify(result.val()));
@@ -308,6 +311,7 @@ export class HelloWorldModel extends Observable {
     firebaseWebApi.database().ref(path).orderByChild(child)
         .once("value")
         .then(result => {
+          console.log("key exists? " + result.exists());
           this.set("path", path);
           this.set("key", result.key);
           this.set("value", JSON.stringify(result.val()));

docs/DATABASE.md

@@ -311,7 +311,8 @@ The link is for the iOS SDK, but it's the same for Android.
       console.log("Listener error: " + result.error);
     } else {
       console.log("Key: " + result.key);
-      console.log("Calue: " + JSON.stringify(result.val()));
+      console.log("key exists? " + result.exists());
+      console.log("Value: " + JSON.stringify(result.val()));
     }
   };
 

src/app/database/index.ts

@@ -5,7 +5,7 @@ import { nextPushId } from "./util/NextPushId";
 export module database {
   export interface DataSnapshot {
     // child(path: string): DataSnapshot;
-    // exists(): boolean;
+    exists(): boolean;
     // exportVal(): any;
     // forEach(action: (a: DataSnapshot) => boolean): boolean;
     // getPriority(): string | number | null;
@@ -35,9 +35,8 @@ export module database {
         } else {
           callback({
             key: result.key,
-            val: () => {
-              return result.value;
-            }
+            val: () => result.value,
+            exists: () => !!result.value
           });
         }
       };
@@ -74,14 +73,13 @@ export module database {
       return null;
     }
 
-    public once(eventType: string, successCallback?: (a: DataSnapshot, b?: string) => any, failureCallbackOrContext?: Object | null, context?: Object | null): Promise<any> {
+    public once(eventType: string, successCallback?: (a: DataSnapshot, b?: string) => any, failureCallbackOrContext?: Object | null, context?: Object | null): Promise<DataSnapshot> {
       return new Promise((resolve, reject) => {
         firebase.getValue(this.path).then(result => {
           resolve({
             key: result.key,
-            val: () => {
-              return result.value;
-            }
+            val: () => result.value,
+            exists: () => !!result.value
           });
         });
       });
@@ -93,9 +91,8 @@ export module database {
         callbacks && callbacks.map(callback => {
           callback({
             key: result.key,
-            val: () => {
-              return result.value;
-            }
+            val: () => result.value,
+            exists: () => !!result.value
           });
         });
       };