FAQ Database Discussion Community

Getting timestamp from Objecify entity?

Is it possible to obtain the timestamp that is used for optimistic concurrency control from an Objectify entity (or a lower-level part of the Google Datastore infrastructure) and if so, how?

Google Cloud BigTable vs App Engine Datastore

What is the difference between Google Cloud Bigtable and Google Datastore / App engine datastore, and what are the main practical advantages/disadvantages? AFAIK the Google Datastore is build on top of bigtable.

Google Datastore app architecture questions

I'm working on a Google AppEngine app connecting to the Google Cloud Datastore via its JSON API (I'm using PHP). I'm reading all the documentation provided by Google and I still have questions: In the documentation about Transactions, there is the following mention: "Transactions must operate on entities that belong...

Managing users authentication in Google App Engine

I am working on a webapp based on google app engine. The application uses the google authentication apis. Basically every handler extends from this BaseHandler and as first operation of any get/post the checkAuth is executed. class BaseHandler(webapp2.RequestHandler): googleUser = None userId = None def checkAuth(self): user = users.get_current_user() self.googleUser...

Generate unique Long Id on App Engine

I've three possible ways user can sign in into our service: login and password Google+ Facebook I want to keep all those user id's in one entity. To avoid id collisions between e.g. Google and Facebook a prefix will be added to id (g- and f- respectively). Currently for users...

Google NDB: How to Make a Keys Only Query By Id

Id like to check whether an entity still exist in a NDB DataStore. I have the Entity's ID and I do not this operation to count as a read operation but I can't see how to make a keys_only = True query while using get_by_id

Google DataStore PHP GDS fetchPage from record

PHP-GDS provides the following method: $obj_store->fetchPage(10); // Gets the first 10 books However this only works within the same connection, I'd like to use something like: $obj_store->fetchPage(n, 10); so I can get a set of items from separate API calls, e.g.: api.php?page=1&items=10 // items 0-10 api.php?page=2&items=10 // items 11-20 api.php?page=3&items=10...

Google datastore multiple values for the same property

I am using Google Datastore for an Android application, the backend is written in Java. In one table, I want to set multiple values to the same property: Entity newGroup = new Entity("group"); newGroup.setProperty("member", "A"); newGroup.setProperty("member", "B"); newGroup.setProperty("member", "C"); datastore.put(newGroup); I then want to query to find all groups a...

How to upload images and storing it in db google app engine

Hello i want to know how to upload a picture from the user and store it in data base using this form ( using google data store) <form method='post'> <input type='file' name='img'> <input type='submit'> i have made a db model from google.appengine.ext import db class Photo(db.model): profile_pic = db.BlobProperty() and...

Weird datastore error in Go, “The kind is the empty string”

I am recently getting an error that I have never seen before when making a simple datastore.GetAll() request. I can't figure out what it means and I can't find any documentation with the error message or any help from Googleing the error message. Here's my code: type MyUnderlyingStruct struct {...

Accessing specific part of object

I have an object I am trying to access and this is the var_dump() object(GDS\Entity)#16 (5) { ["str_kind":"GDS\Entity":private]=> string(13) "User Sessions" ["str_key_id":"GDS\Entity":private]=> string(16) "5649391675244544" ["str_key_name":"GDS\Entity":private]=> NULL ["mix_ancestry":"GDS\Entity":private]=> NULL ["arr_data":"GDS\Entity":private]=> array(1) { ["session_id"]=> string(3) "123" } } I know if I wanted to get the session_id and this object was stored...

Use Google App Engine's NDB as a message queue?

Has anyone tried to use NDB as a message queue? We have several consumers and producers, which may want to do broadcast, multicast, and publish-subscribe. I've read several documents on why using a RDBMS as a message queue is bad. But in my case, my app can tolerate latency of...

Unmarshal datastore.ByteString go

Hi im trying to unmarshal datastore entity that contain ByteString field. But i'm getting unmarshal error, i can't figure out a way to unmarshal it Should i create my own PropertyLoadSaver ?? json: cannot unmarshal string into Go value of type datastore.ByteString package main import ( "encoding/json" "fmt" "google.golang.org/appengine/datastore" )...

Connecting to Google Datastore using gcloud

I am trying to connect to my Google Datastore instance but I can't find any sample code for how to initialize a connection! Gcloud's main documentation immediately starts with how to assign an Entity or a Query but skips the crucial connection bit. The demo section seems specific to the...

Migration from Google cloud sql to datastore

Is there an easy way to migrate a large (100G) Google cloud sql database to Google datastore? The way that comes to mind is to write a python appengine script for each database and table and then put it into the datastore. That sounds tedious but maybe it has to...

Where is data stored when installed while logged on to a Google Cloud Compute instance?

I'm following this tutorial to get started with the Google Cloud Datastore: https://cloud.google.com/datastore/docs/getstarted/start_java/. At this point I have my Cloud account all set up with the APIs needed to use Datastore and Endpoints for a project I am working on. I was following the setup instructions and so far I...

Export Google Cloud Datastore and import to BigQuery programmatically

I'm looking for a method to export my Cloud DataStore and import it into Big Query daily. The manual way is described at google page. I do not find a clean way to automate it.

Google App Engine - ByteString query fails

I am working on a Go application in which I have an Entity with a Property that holds an identifying token which is a random string of bytes. I am storing this property as a ByteString, and in my development environment I have been able to query for this property...

Objectify transaction rollback not happening

When I intentionally throw an exception within an Objectify transaction, my transaction is not being rolled back. What am I doing wrong? @Inject Dao dao ... public void testTransaction(){ dao.transact(new VoidWork() { @Override public void vrun() { Key aclKey= dao.save().entity(acl).now(); //expecting this to be rolled back //throw exception if(true) throw...

Using App Engine Cloud Endpoints to access ndb datastore

I'm sorry if this question is redundant or not well-conceived, but I am new to App Engine, and I'm not sure about the best practices for what I'm attempting to do. I have an iOS app, and I want to use http GET and POST requests to put and query...

How to create multiple entities dynamically in google app engine using google data storage(python)

I wish to implement this: There should be an entity A with column 1 having values a,b,c...[dynamically increases by user's input] There should be another entity B for each values of a , b , c.. How should I approach this problem? Should I dynamically generate other entities as user...