[appengine-java] Re: Writing to the high replication datastore
Thank you very much for your help! I will have a look through some files . But i am still not shure why the reference is going wrong I use eclipse but the imports looks like going fine -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To view this discussion on the web visit https://groups.google.com/d/msg/google-appengine-java/-/nK0f1PUlVUQJ. To post to this group, send email to google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Writing to the high replication datastore
Hi, I have never worked with datastores before but i want to write to the datastore but when i try to use the samples from docs i get these errors *Caused by: java.lang.Error: Unresolved compilation problems: The import com.google.android cannot be resolved The import com.google.appengine.api.datastore cannot be resolved The import com.google.appengine.api.datastore cannot be resolved The import com.google.appengine.api.datastore cannot be resolved The import com.google.appengine.api.datastore cannot be resolved PMF cannot be resolved DatastoreService cannot be resolved to a type DatastoreServiceFactory cannot be resolved Entity cannot be resolved to a type Entity cannot be resolved to a type* if have put this code in the code for my widget DatastoreService datastore = DatastoreServiceFactory.getDatastoreService(); Entity employee = new Entity(Employee); employee.setProperty(firstName, Antonio); employee.setProperty(lastName, Salieri); employee.setProperty(attendedHrTraining, true); datastore.put(employee); What is the problem please help me (sorry for the bad english) -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To view this discussion on the web visit https://groups.google.com/d/msg/google-appengine-java/-/xdTilZyb3GkJ. To post to this group, send email to google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: Checking if I understand transactions correctly
Huh?
As you are only able to do work in a single transactional unit-of-work
on a single entity-group, rollback must be considered usefull.
In the above mentioned snippet, an Account entity is looked-up,
updated and a child entity TransactionRecord is added, all in a single
entity-group, namely the Account's. So a rollback will undo all
operations.
If you had added TransactionRecord to, lets say a TransactionRecords
entity-group, you would have gotten an error if you were operating in
a transactional scope, or no-transaction support at all, hence a
rollback would not have been possible.
Cheers, Lars Borup Jensen
On 1 Jun., 06:21, Didier Durand durand.did...@gmail.com wrote:
Hi,
entity group is not useful at rollback but rather limits you to which
updates you can do: all the entities you touch in a single transaction
must be in the same entity group.
So, designing your groups properly is a key design issue in GAE to
avoid unnecessary complexity when you later need to update at once
entities that you created before in various groups.
regards
didier
On May 30, 7:57 am, Jacob jacob.rho...@gmail.com wrote:
I am writing some code that needs to do a rollback on a secondary
object/table should the transaction fail, I believe this can be done
via entity groups, however I am not sure if this is how it would be
implemented. I have written some sample code to check if what I would
be doing is correct?
Would the following code ensure the Account object is never updated
if the insert of the TransactionRecord object fails.
public void addTransaction(String account, Double value, String
description, Date date) throws EntityNotFoundException {
DatastoreService datastore =
DatastoreServiceFactory.getDatastoreService();
int retries = 3;
while (true) {
Transaction txn = datastore.beginTransaction();
try {
// Update the bank balance
Key key = KeyFactory.createKey(Account,
account);
Entity e = datastore.get(key);
Double balance = (Double)
e.getProperty(balance);
balance += value;
e.setProperty(balance, value);
datastore.put(e);
// Record transaction details
Entity d = new Entity(TransactionRecord,
key);
d.setProperty(account_key, key);
d.setProperty(date, date);
d.setProperty(value, value);
d.setProperty(description, description);
txn.commit();
break;
} catch (ConcurrentModificationException e) {
if (retries == 0)
throw e;
--retries;
} finally {
if (txn.isActive())
txn.rollback();
}
}
}
Thanks for any feedback!
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[appengine-java] Re: Login redirect failing all of a sudden /_ah/conflogin
Where and when was this change announced? It is causing a major inconvenience right now before we are able to push a new release with the suggested workaround. I don't want to end up in this situation ever again. We have built a client-side web application using HTML5 that stores information in the cloud using Google App Engine, and we need to redirect back to the site hosting the client app after the login. The funny thing is that after I see the error and go back to the site hosting the client app I am still not logged in, so I suppose that there is an extra step in the login procedure that does not got executed right now? Regards, Lars On Mar 4, 8:59 pm, Jon McAlister jon...@google.com wrote: The workaround is to have the app perform the redirect. That is, createLoginUrl only works when the continue url is a url for the app. If you need the user to be sent to another app/host after login, then your app needs to do that redirect. On Fri, Mar 4, 2011 at 11:47 AM, Glenn glenn.mur...@gmail.com wrote: What was the good workaround? Our login is broken, too. We have two App Engine apps: one is the front end and one the back end, with a REST API. When the user accesses the front end a call to the back end is made where redirect = userService.createLoginURL(gae front end); is called. In this case both apps have appspot.com urls and it worked well. We are dead in the water now. Please help! Thanks, Glenn On Mar 2, 12:31 pm, Jon McAlister jon...@google.com wrote: Looks like you pushed a good workaround already, but yes that was a result of a new login system yesterday, and looks like it is not handling this case like the prior system did. Specifically, calling createLoginUrl where the continue url is not the same as the url the app is hosted on. And, furthermore, the continue url is not an app engine url at all. For now, what you did was a good workaround. That is, use an app engine url as the continue url, and then have the app engine app redirect to the non-app-engine url. Need to think on this case some more. On Wed, Mar 2, 2011 at 7:53 AM, Joerg Weingarten jbwinvest...@gmail.com wrote: Since this morning my call to userservice.createLoginUrl produces a url that doesn't work anymore. When selecting my Sign in link, which has a url like: https://www.google.com/accounts/ServiceLogin?service=ahpassive=true;... I get the error: The requested URL /_ah/conflogin was not found on this server. Somebody please help. Thx ---Joerg--- -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group athttp://groups.google.com/group/google-appengine-java?hl=en. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group athttp://groups.google.com/group/google-appengine-java?hl=en. -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: Lightweight Best performing MVC framework - Recommendation
+1 on Stripes. Extremely easy to setup and use - very powerfull and performs quite well on GAE as its basically just a somewhat simple filter/servlet and JSP with a stripes taglib though still, as I said, powerfull. I had to make a few adjustments to get it to serve @UrlBinding(/) for example and I ALWAYS want it to exec controller before being forwarded to any JSP files. Regards, Lars Borup -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Inverted Index
Hi guys, Since there is no full-text search available in GAE/j and I really need this for a new app I am writing I have made a prototype implementation of an inverted index using GAE store. Term is stored as a key with actual term as name in key (only key is needed) Below each term I've added document references as another key like this Term(term)/DocumentRef(10) where 10 is the internal document number. An example: Term(stuff) DocRef(1) DocRef(2) Term(more) DocRef(1) When searching for e.g. more stuff (which is boolean and) I do this: Query DocRef's from the Term with the least doc-refs (children, this info is cached) and load keys into a sorted set. Then query for doc-refs under the second term filtering from the min. doc-id in the sorted set and the max doc-id (meaning we only get possible matches in the docs we've know contains the first term. Merge sets. What do you think? Is this a fair way to implement this (working on scoring using tf-idf) and do you think its possible to get it to perform well? /Lars Borup -- You received this message because you are subscribed to the Google Groups Google App Engine for Java group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Failing to retrieve child-objects in a one-to-many JDO relation in datastore
Hi,
I am failing to retrieve child-objects in a one-to-many JDO relation
in the datastore. The case is as follows;
I have two classes (Parent Child, code-snippet below) with a defined
one-to-many relation.
It is no problem storing the structure with the 'store'-operation
defined below. This is easily verified by web-browsing the datastore.
However, when retrievning the parent-object from the datastore
('fetchParents'), the ''childs' attribute is always null. What must be
done to (auto-)populate this attribute from the datastore?
Also, the 'parent'-attribute of the Child-objects will also be null if
they are fetched in a similar way.
All clues appreciated...
Lars
- - - - - - - Code samples below - - - - - -
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class ParentDTO {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
@Extension(vendorName=datanucleus, key=gae.encoded-pk,
value=true)
private String encodedKey;
@Persistent
public String name;
@Persistent(mappedBy=parent)
public ListChild childs;
public ParentDTO()
{
}
public void add(Child c)
{
if (childs == null)
childs = new ArrayListChild();
kids.add(c);
}
}
- - - -
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Child {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
@Extension(vendorName=datanucleus, key=gae.encoded-pk,
value=true)
public String encodedKey;
@Persistent
public String name;
@Persistent
public Parent parent;
public Child()
{
}
public String getEncodedKey() {
return encodedKey;
}
}
- - - - -
Storing to datastore (works perfectly)
public void store()
{
Parent p = new Parent();
p.navn = nils;
Child c = new Child();
c.name = jim;
p.add(c);
c = new ChildDTO();
c.name = anne;
p.add(c);
PersistenceManager pm =
PMF.get().getPersistenceManager();
try {
pm.makePersistent(p);
} catch (Exception ee) {
res = ee.getMessage();
} finally {
pm.close();
}
}
- - - - - - Fetching data (not working)
public String fetchParents()
{
String res = ;
PersistenceManager pm = PMF.get().getPersistenceManager();
javax.jdo.Query query = pm.newQuery(Parent.class);
ListParent parents = (ListParent) query.execute();
IteratorParent iterF = parents.iterator();
while (iterF.hasNext()) {
Parent f = iterF.next();
res = res + : + f.name;
if (f.childs != null) { // this is the problem
- 'this.childs' is
always null
IteratorChild iterI =
f.childs.iterator();
while (iterI.hasNext()) {
Child idto = iterI.next();
res = res + + idto.name;
}
}
}
pm.close();
}
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