How does one sync live to dev datastores on Google App Engine?
I've got some data up on Google App Engine's live datastore, but would like to have a local copy as well for local development. What's the best way to do an occasional sync? ...
gae-datastore
How to I determine if an object exists for a given key in the Google AppEngine datastore using Java?
I'm trying to port the Sharding Counters example (code.google.com/appengine/articles/sharding_counters.html) to Java. The only problem is that the Java API does not have a call similar to Python's 'get_by_key_name'. This is the basic idea: Transaction tx = pm.currentTransaction(); Key key = KeyFactory.createKey(C...
App Engine datastore does not support operator OR
I am trying to query the google datastore for something like (with pm --> persistanceManager): String filters = "( field == 'value' || field == 'anotherValue' )"; Query query = pm.newQuery(myType.class, filters); When I execute - I am getting back: App Engine datastore does not support operator OR. What's the best approach in peop...
Google Datastore problem with query on *User* type
On this question I solved the problem of querying Google Datastore to retrieve stuff by user (com.google.appengine.api.users.User) like this: User user = userService.getCurrentUser(); String select_query = "select from " + Greeting.class.getName(); Query query = pm.newQuery(select_query); query.setFilter("author == paramAuthor"); que...
How to dynamically build JDO Queries on multiple parameters
One can easily use JDO syntax to query on multiple parameters as follows: //specify the persistent entity you're querying and you filter usign params query = pm.newQuery(MyClass.class, " customer == paramCustomer && date >= paramStartDate && date <=paramEndDate "); // declare params used above query.declareParameters("com.google.appeng...
GWT with JDO problem
I just start playing with GWT I'm having a really hard time to make GWT + JAVA + JDO + Google AppEngine working with DataStore. I was trying to follow different tutorial but had no luck. For example I wend to these tutorials: TUT1 TUT2 I was not able to figure out how and what i need to do in order to make this work. Please look at my s...
Could my embedded key/value datastore eventually exceed an App Engine limit?
I have a BerkeleyDB key/value datastore embedded in my Google App Engine project, which does not use the Google Datastore. When I upload the application to Google App Engine, the database will be less than 1MB. But is it possible that, as it grows, over time it will eventually exceed an App Engine file-size limitation? What would be ...
App Engine Datastore IN Operator - how to use?
Reading: http://code.google.com/appengine/docs/python/datastore/gqlreference.html I want to use: := IN but am unsure how to make it work. Let's assume the following class User(db.Model): name = db.StringProperty() class UniqueListOfSavedItems(db.Model): str = db.StringPropery() datesaved = db.DateTimeProperty() clas...
How do I delete all entities from my local Google App-engine datastore?
How can I remove all entities or reset the local datastore on my dev_appserver? I accidentally recursively called a function to create an entity when testing. I am using the Google App-engine SDK on Vista with Python. ...
Storing hierarchical data in Google App Engine Datastore?
Can someone illustrate how I can store and easily query hierarchical data in google app engine datastore? ...
Send objects from/to Java using GWT
To learn GWT and Google AppEngine (GAE) I'm trying to create a simple application using GWT with two or three objects (entities). In this application one object, let's say Student, encapsulates ArrayList of other objects, say Classes and Books. Then it creates list of Students and sends it to Java code on GAE and stores it to the data st...
Question on Google Appengine Datastore Optimization
I have hierarchical data stored in the datastore using a model which looks like this: class ToolCategories(db.Model): name = db.StringProperty() parentKey = db.SelfReferenceProperty(collection_name="parent_category") ... ... I want to print all the category names preserving the hierarchy, say in some form like this : --I...
Detecting first time login of user into application (Google Appengine)
My app requires users to login using their google account. I have this set in my App.yamp file: url: /user/.* script: user.py login: required Now when any user tries to access files under /user/secret.py he will need to authenticate via google, which will redirect the user back to /user/secret.py after successful authentication. ...
Does Key.from_path hit the datastore?
I have a list of key names that I want to bulk fetch (the key names are stored in a StringListProperty attached to an entity). My general plan was to do: usernames = userrefInstance.users # A collection of strings on another model. keys = [Key.from_path('User', key_name) for username in usernames] users = db.get(keys) My questio...
How do Datastore and App versions work on GAE/J
One can deploy several versions of the same application on GAE/J, but how does GAE/J deal with the fact that different versions can use different Datastore (and possibly incompatible) schemes? Example: Suppose that on version 1 of my application I have a POJO like (I've left out the several details for sake of simplicity): public cla...
ClassCastException when trying to add child to parent in owned one to many. (using jdo on google appengine)
I need some help figuring out what I'm doing wrong here. I am trying to master one to many relationships and running into a roadblock. I tried to modify the Employee and ContactInfo example to do one to many mappings: Everything works if I create both the parent (employee) and child (Contact) and then call makePersistent. But if I try ...
Store Binary files on GAE/J + Google DataStore
I'm building application on Google AppEngine with Java (GAE/J) and all my data will be stored in Google DataStore. Now, what if I want to save some binary file, let's say Images (JPG, PNG, etc), DOC, TXT, Video Files how do i deal with these? Or what if i want to stream video files (SWF) where and how should i store those files and when ...
How to delete all datastore in Google App Engine?
Does anyone know how to delete all datastore in Google App Engine? ...
Google App Engine datastore does not support operator +
I'm playing with GAE, and need to make a query with something like this: select from models.Post as p where (p.votesUp + p.votesDown > 10) But I get this error: App Engine datastore does not support operator + Which could be a good approach to replace that query? ...
App engine datastore: How to implement Posts and Tags without joins?
I'm building an application in Google App Engine (Java), where users can make posts and I'm thinking in adding tags to these posts, so I will have something like this: in entity Post: public List<Key> tags; in entity Tag: public List<Key> posts; It would be easy to query, for example, all posts with a certain tag, but how could I ...