Dennis,
from the error message you're getting, it seems to me that you're
somehow trying to render a node that represents a null location.
Maybe your dao returns a list and some (or one) of the list items is null.
To check if this is the case, you can try this LocationTree.html
<div id="treeArea">
<div jwcid="tree" id="tree">
<span jwcid="@If" condition="ognl:location!=null">
<span jwcid="nodeLink">
<span jwcid="nodeLabel" />
</span>
</span>
</div>
</div>
and see what happens.
> Dear Tacos developers,
>
> First of all thanks for the very nice tapestry plug in. It solves all my
> needs for AJAX driven websites in T4 :)
>
> Unfortunately there is one thing (atm ;)) I cannot get to work and that
> is the advanced tree. I've noticed some more ppl that have problems with
> it and therefore I'm posting this email. I'd like to make a very
> elaborate case here and maybe this (in some modified form or another)
> can be added to the examples so that this is more trivial to implement
> for everybody.
>
> Therefore this is going to be a _long_ message, filled with files and
> examples.
>
> In anycase, first off: the story. I'm digging trough a data collection
> filled with locations. Locations have an id, name and a parent id. These
> locations happen to be ideally suited for tree work as they represent
> locations on earth! The first layer are countries, the second layer are
> states and so on (cities, streets, houses, rooms).
>
> This will offcourse be a very large amount of data that you do not want
> to load all at once. To keep in line with the largeness of this database
> I've decided to use Hibernate (and ejb3, but that's not important).
> Locations are defined in an Hibernate entity file:
>
> ------ Location.java ------
> @Entity
> @Table(name="Locations")
> public class Location implements Serializable {
>
> private static final long serialVersionUID = -109168154630091533L;
>
> long id;
> String name;
> Location parentLocation;
> Set<Location> childLocations = new HashSet<Location>();
>
> @Id(generate=GeneratorType.AUTO)
> public long getId() {
> return id;
> }
> public void setId(long id) {
> this.id = id;
> }
>
> @Column(nullable=false)
> public String getName() {
> return name;
> }
> public void setName(String name) {
> this.name = name;
> }
>
> @OneToOne
> @JoinColumn(name="parentId")
> public Location getParentLocation() {
> return parentLocation;
> }
> public void setParentLocation(Location parentLocation) {
> this.parentLocation = parentLocation;
> }
>
> @OneToMany(mappedBy="parentLocation")
> public Set<Location> getChildLocations() {
> return childLocations;
> }
> public void setChildLocations(Set<Location> childLocations) {
> this.childLocations = childLocations;
> }
> }
> ------ EOF Location.java ------
>
> Just very simply all the needed getters and setters for the Id, Name,
> Parent and Children. Nothing too fancy here yet. This data will be shown
> in a tapestry page that is surrounded by a border (not really important
> here). The HTML code for the tapestry page is:
>
> ------ LocationTree.html ------
>
> <body jwcid="@Border" title="Home">
>
> <div id="treeArea">
> <div jwcid="tree" id="tree">
> <span jwcid="nodeLink">
> <span jwcid="nodeLabel" />
> </span>
> </div>
> </div>
>
> </body>
> ------ EOF LocationTree.html ------
>
> Please not that I don't use an icon here, maybe loading it from the
> database will be a version 2 of this example. With this page there also
> must be a tapestry page file, defining all the nice components that are
> used in the HTML.
>
> ------ LocationTree.page ------
> <page-specification class="<fill in tacos classpath here>.LocationTreePage">
>
> <description>Location Tree</description>
>
> <property name="location" />
> <property name="selectedLocation" persist="session"/>
> <property name="locationState" persist="session"
> initial-value="ognl: new java.util.HashSet()" />
>
> <bean name="evenOdd" class="org.apache.tapestry.bean.EvenOdd" />
>
> <component id="nodeLink" type="tacos:AjaxDirectLink">
> <binding name="listener"
> value="ognl:components.tree.listeners.contentExpansion"/>
> <binding name="parameters"
> value="ognl:{keyProvider.getKey(components.tree.value), not
> components.tree.isExpanded(components.tree.value),location.parentLocation}"/>
> <binding name="updateComponents"
> value="ognl:{location.parentLocation, 'selectedLocation' }"/>
> <binding name="effects" value="template:%nodeLink.effects"/>
> </component>
>
> <component id="nodeLabel" type="Insert">
> <binding name="value"
>
value="ognl:@[EMAIL PROTECTED](location.name)"/>
> <binding name="class" value="ognl:location == selectedLocation ?
> 'selected' : null"/>
> </component>
>
> <component id="tree" type="tacos:Tree">
> <binding name="contentProvider" value="ognl:contentProvider"/>
> <binding name="keyProvider" value="ognl:keyProvider"/>
> <binding name="value" value="ognl:location"/>
> <binding name="state" value="ognl:locationState"/>
> <binding name="sorter"
> value="ognl:@[EMAIL PROTECTED]"/>
> <binding name="rowStyle" value="ognl:beans.evenOdd" />
> <binding name="partialBlockClass" value="literal:treeBlock" />
> <binding name="linkListener" value="listener:select" />
> </component>
>
>
> <inject property="ajaxEngine" object="service:tacos.ajaxdirect" />
>
> </page-specification>
> ------ EOF LocationTree.page ------
>
> As shown in the page file, we use the LocationTreePage.java class for
> the code-part of this page. As you can see in the
> select() call I'm kinda stuck here, but in anycase tapestry explodes
> before this is ever called.
>
> ------ LocationTreePage.java ------
> public abstract class LocationTreePage extends BasePage {
>
> Logger logger = Logger.getLogger( this.getClass().getName() );
>
> private final static ITreeContentProvider CONTENT_PROVIDER = new
> LocationTreeContentProvider(null);
>
> public abstract Location getSelectedLocation();
> public abstract void setSelectedLocation(Location location);
>
> public abstract Set getLocationState();
>
> public abstract AjaxDirectService getAjaxEngine();
>
> public ITreeContentProvider getContentProvider() {
> return CONTENT_PROVIDER;
> }
>
> public IKeyProvider getKeyProvider() {
> return LocationKeyProvider.INSTANCE;
> }
>
> public ITreeManager getTreeManager() {
> return new TreeManager(getLocationState(), getContentProvider(),
> getKeyProvider() );
> }
>
> public void select(IRequestCycle cycle) {
> // I'm stuck here
> }
>
> public void revealSelected(IRequestCycle cycle) {
> getTreeManager().reveal(getSelectedLocation());
> }
> }
> ------ EOF LocationTreePage.java ------
>
> The comparation is done by the following class. Please note that we
> should do something better here, but I havn't gotten around to thinking
> about that.
> ------ LocationComparator.java ------
> public class LocationComparator implements Comparator {
>
> public final static Comparator INSTANCE = new LocationComparator();
>
> public int compare(Object o1, Object o2)
> {
> Location location1 = (Location)o1;
> Location location2 = (Location)o2;
>
> if( location1.equals(location2) ) {
> return 0;
> }
>
> return 1;
> }
> }
> ------ EOF LocationComparator.java ------
>
> The keys are provided with the following class:
> ------ LocationKeyProvider.java ------
> public class LocationKeyProvider implements IKeyProvider {
>
> public final static LocationKeyProvider INSTANCE = new
> LocationKeyProvider();
>
> public Serializable getKey(Object value) {
> return ((Location) value).getId();
> }
> }
>
> ------ EOF LocationKeyProvider.java ------
>
> Finally the last class that is used provides the actual data, there is a
> but of custom datahandling in here. I use JNDI calls to get a EJB3bean
> that knows about CRUD functions.
>
> ------ LocationKeyContentProvider.java ------
> public class LocationTreeContentProvider implements ITreeContentProvider {
>
> Logger logger = Logger.getLogger( this.getClass().getName() );
>
> private final Location rootLocation;
>
> /**
> * Constuctor that starts to build the tree somewhere
> * @param rootLocation
> */
> public LocationTreeContentProvider(Location rootLocation) {
> this.rootLocation = rootLocation;
> }
>
> public Collection getChildren(Object parentElement) {
> return ((Location)parentElement).getChildLocations();
> }
>
> public boolean hasChildren(Object parentElement) {
> /**
> if( ((Location)parentElement).getChildLocations().size() > 0 ) {
> return true;
> }
> return false;
> */
> return false;
> }
>
> public Object getParent(Object childElement) {
> return ((Location)childElement).getParentLocation();
> }
>
> public List getElements()
> {
> // Get initial context
> LocationBean locationBean=null;
> try{
> locationBean = (LocationBean)(new
> InitialContext()).lookup(LocationBean.class.getName());
> } catch (Exception e){
> logger.error( "Unable to get location bean: " +
> e.getMessage() );
> return Collections.EMPTY_LIST;
> };
>
> // Return the list of rootlocations
> List<Location> list =
> locationBean.findByParentLocation(rootLocation);
>
> return list;
> }
>
> }
> ------ EOF LocationKeyContentProvider.java ------
>
> Just to be complete here is the listing for the EJB:
>
> ------ LocationBeanImpl.java ------
> @Stateless
> public class LocationBeanImpl extends GenericEJBDAO<Location, Long>
> implements LocationBean {
>
> /**
> * Use constructor to tell GenericEJBDAO our class
> */
> public LocationBeanImpl() {
> super(Location.class);
> }
>
> /* (non-Javadoc)
> * @see
>
com.stocketeer.ejb.impl.LocationBean#findByParentLocation(com.stocketeer.par.Location)
> */
> @SuppressWarnings("unchecked")
> public List<Location> findByParentLocation(Location parentLocation)
> {
> if( parentLocation == null ) {
> return this.em.createQuery("from Location as location where
> location.parentLocation = null").
> getResultList();
> }
> else {
> return this.em.
> createQuery("from Location as location where
> location.parentLocation = ?"
> ).setParameter(0, parentLocation.getId()
> ).getResultList();
> }
> }
> }
> ------ EOF LocationBeanImpl.java ------
>
> Oof, that was a lot of c/p and a bit of typing, but I'm hoping that you
> can point me to my errors and include something that makes it easier for
> us noob users to use all this fancy functionality. In anycase keep up
> the good work and thanks in advance.
>
> With this I'm getting an error:
> org.apache.tapestry.BindingException
> Unable to read OGNL expression '<parsed OGNL expression>' of
> [EMAIL PROTECTED]: source is null for
> getProperty(null, "name")
>
>
> --
> Kind regards,
>
> Dennis Fleurbaaij
> E: [EMAIL PROTECTED]
> T: (0031) (0) 6 54 21 53 65
>
>
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