Out comes the ruler to whack your knuckles; you're doing your testing and
experimenting on the dev server.
It's really quite simple to do it on your desktop if you follow their
instructions for unit testing. And much faster; none of that uploading,
waiting, etc. Make a change, recompile, right click on package or java file
and select Run as JUnit test (in eclipse).
dataStorm wrote:
> I don't think it made a difference, if I check the online datastore it
> says "<null>" for "selectedTags". I think I am still missing
> something.
>
> Here is my other 'tags' class, not sure if it matters for my datastore
> relationship :
>
>
> =======================
>
>
>
> @PrimaryKey
> @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY,
> defaultFetchGroup="true")
> private Key tagid;
>
> @Persistent(defaultFetchGroup= "true")
> private Set<Key> selectedLinks;
>
>
> @Persistent
> private String tagname;
>
> @Persistent
> private Date date;
>
> public Tagstore(String tagname, Date date) {
>
> this.tagname = tagname;
> this.date = date;
> }
>
> public Key getId() {
> return tagid;
> }
>
>
> public String getKeyAsString() {
> if (tagid == null) return null;
> return KeyFactory.keyToString(tagid);
> }
>
>
> public String getTag() {
> return tagname;
> }
>
> public Date getDate() {
> return date;
> }
>
> public void setTag(String tagname) {
> this.tagname = tagname;
> }
>
> public void setDate(Date date) {
> this.date = date;
> }
>
>
>
>
>
> =======================
>
> I'm putting "defaultFetchGroup="true"" everywhere hoping it would
> help ....
>
>
> =======================
>
>
> On Nov 1, 9:11 pm, Rusty Wright <[email protected]> wrote:
>> Linkstore doesn't have a no-arg constructor does it? If so, then
>> selectedTags could be null. You could change its declaration to
>>
>> @Persistent(defaultFetchGroup = "true")
>> private Set<Key> selectedTags = new HashSet<Key>(0);
>>
>> I've always initialized my Collections at the declaration.
>>
>> Just for experimentation, try changing its declaration to that and see what
>> happens.
>>
>> WATCH OUT THOUGH: if you you're using eclipse you may have it configured to
>> add a final to fields and variables that are set when they're declared and
>> not subsequently written to. If that happens then DataNucleus ignores final
>> fields. (I wish I could change some setting to have DN throw an exception
>> in that situation.)
>>
>> dataStorm wrote:
>>> Hello, can someone help me with this, I am trying to follow this post
>>> http://code.google.com/appengine/docs/java/datastore/relationships.html
>>> to
>>> create relationship between LINKS and TAGS.
>>> I am getting an error:
>>> Caused by:
>>> java.lang.NullPointerException
>>> at com.linkytty.Linkstore.addNewTag(Linkstore.java:101)
>>> at com.linkytty.TagLinker.doPost(TagLinker.java:52)
>>> This happens when I try to add a key using ".add()" :
>>> public void addNewTag(Key tagKey) {
>>> selectedTags.add(tagKey);
>>> }
>>> addNewTag() is called from my
>>> PersistenceManager pm = PMF.get().getPersistenceManager();
>>> Linkstore linkObject = pm.getObjectById(Linkstore.class, objectKey);
>>> linkObject.addNewTag(objectKey);
>>> I've logged my "objectKey" and etc. and it seems that it gets those
>>> right
>>> (
>>> String linkKeyId = req.getParameter("key");
>>> linkKeyID : aghsaW5reXR0eXIPCxIJTGlua3N0b3JlGAUM
>>> Key objectKey = KeyFactory.stringToKey(linkKeyId);
>>> objectKey: Linkstore(5)
>>> )
>>> My Classes:
>>> the class that creates links:
>>> public class Linkstore {
>>> @PrimaryKey
>>> @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
>>> private Key linkid;
>>> @Persistent(defaultFetchGroup = "true")
>>> private Set<Key> selectedTags;
>>> //STUFF HERE
>>> public Linkstore(User author, String linkcontent, String linkcomment,
>>> Date
>>> date) {
>>> this.author = author;
>>> this.linkcontent = linkcontent;
>>> this.linkcomment = linkcomment;
>>> this.date = date;
>>> selectedTags = new HashSet<Key>();
>>> }
>>> public Key getId() {
>>> return linkid;
>>> }
>>> public String getKeyAsString() {
>>> if (linkid == null)
>>> return null;
>>> return KeyFactory.keyToString(linkid);
>>> }
>>> // STUFF HERE
>>> public void addNewTag(Key tagKey) {
>>> selectedTags.add(tagKey);
>>> }
>>> }
>>> The class that captures the post:
>>> public void doPost(HttpServletRequest req, HttpServletResponse resp)
>>> throws IOException {
>>> String linkKeyId = req.getParameter("key");
>>> Key objectKey = KeyFactory.stringToKey(linkKeyId);
>>> String tagStringKey = req.getParameter("tagkey");
>>> Key tagObjectKey = KeyFactory.stringToKey(tagStringKey);
>>> PersistenceManager pm = PMF.get().getPersistenceManager();
>>> Linkstore linkObject = pm.getObjectById(Linkstore.class,
>>> objectKey);
>>> linkObject.addNewTag(objectKey);
>>> resp.sendRedirect("/");
>>> }
>>> ///
>>> Does the "@Persistent(defaultFetchGroup = "true")" make any
>>> difference?
>>> Help & Thanks!
> >
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