[appengine-java] Re: java.lang.NoClassDefFoundError
you can stub out this class into a separated module, say common module, which will be inherited by other modules in need. On Sun, Oct 18, 2009 at 11:00 AM, Sean Mitchell wrote: > > > A bit more searching turned up a workaround on this thread: > > http://groups.google.com/group/google-appengine-java/browse_thread/thread/dd84e44f604498c4 > > > --~--~-~--~~~---~--~~ 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: Failing to retrieve child-objects in a one-to-many JDO relation in datastore
Hi Lars,
Try to annotate your relationship as follows:
@Persistent(mappedBy="parent", default-fetch-group="true")
public List childs;
On Tue, Oct 20, 2009 at 12:19 AM, Lars wrote:
>
> 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 List childs;
>
>public ParentDTO()
>{
>
>}
>
>public void add(Child c)
>{
>if (childs == null)
>childs = new ArrayList();
>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);
>List parents = (List) query.execute();
>Iterator 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
>Iterator iterI =
> f.childs.iterator();
>while (iterI.hasNext()) {
>Child idto = iterI.next();
>res = res + ">" + idto.name
> ;
>}
>}
>}
>pm.close();
>}
>
> >
>
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[appengine-java] Re: Can anyone provide me an example on add/remove tag to an Entity?
Hi Rusty, Thanks for your reply. I know that is a tag, but what I am looking for is how to implement using GAE. Hi Jason, I can not make my question more specific because I totally have no idea on it. :) Can I say we just simply put a Set to an Entity? Then how can I make use of it when making a global search? Shall we iterate through every Set? If that's the case, then what's the difference between Set and Set ? Regards, Max On Wed, Oct 21, 2009 at 1:23 AM, Jason (Google) wrote: > Hi Max. This is currently the only reference available: > > http://code.google.com/appengine/docs/java/javadoc/com/google/appengine/api/datastore/Category.html > > Do you have any specific questions around it? > > - Jason > > > On Sat, Oct 17, 2009 at 10:02 AM, Max wrote: > >> >> I am not able to find a good reference on: >> com.google.appengine.api.datastore.Category >> >> Thanks >> Max >> >> > > > > --~--~-~--~~~---~--~~ 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: why dont my two longs equal each other?
persistence layer will try to set a "null" if one field has not been
initialized, which leads to an exception. So you shall not try to persist a
primitive type
use Comparable.compare(Comparable o) instead, as nclemeur suggested.
On Wed, Oct 21, 2009 at 6:20 PM, John V Denley
wrote:
>
> AHHH, that actually explains a lot of other problems I have been
> seeing with "Long" that i wasnt expecting
>
> so why would anyone use Long rather than long? Im guessing that long
> is actually a basic datatype I suppose I can go look that up
> myself though!
>
> Thanks for your help and input... I wish id figured that out at about
> midnight last night, I could have gone to bed 4 hours earlier!!! LOL
>
> On Oct 21, 3:44 am, nclemeur wrote:
> > Just use
> > StoredID.equals(ID)
> >
> > These are objects in Java, so you need to use equals (or
> > StoreID.longValue==ID.longValue)
> >
> > Cheers
> >
> > Nicolas
> >
> > On Oct 21, 12:39 pm, John VDenley wrote:
> >
> > > OK so Im sending in an ID number (Long) and Im doing a query on the
> > > datastore, getting all the "contacts" in the database, using the
> > > "getID" function to get the "StoredID" and comparing the ID's.
> >
> > > However for some reason the boolean "test" below never becomes true,
> > > despite after stepping through the program there are times when
> > > StoredID=16 and ID=16, but yet (StoredID==ID) does not evaluate to
> > > "true"
> >
> > > anyone got any ideas?
> >
> > > public String updateContact(Long AdminID, Long ID, String
> > > Name,String Phone, String KnownAs, String Notes) throws
> > > NotLoggedInException {
> >
> > > Contact ContactToUpdate=null;
> > > Long StoredID;
> >
> > > PersistenceManager pm = PMF.get().getPersistenceManager();
> > > try {
> > > Query q = pm.newQuery(Contact.class, "AdminID == AID");
> > > q.declareParameters("Long AID");
> > > List Contacts = (List)
> q.execute(AdminID);
> > > for (Contact contact : Contacts)
> > > {
> >
> > > StoredID=contact.getID();
> > > boolean test=(StoredID==ID);
> > > if (test)
> > > {
> > > ContactToUpdate=contact;
> > > }
> > > else
> > > {
> > > ContactToUpdate=null;
> > > }
> > > }
> > > }
> > > finally
> > > {
> > > pm.close();
> > > }
> > > }
> >
>
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[appengine-java] Re: LIKE query workaround for the Low Level API
So far as I know, Bigtable only supports: myString LIKE "foo,%" On Fri, Oct 23, 2009 at 6:24 AM, Nicholas Albion wrote: > > I don't suppose it's possible to do: > >myString LIKE "%,foo,%" > > I'm surprised that the datastore used by a search engine doesn't have > better support for string searching/comparison... > > > --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
