/ by zero Exception with lazyload+livescroll datatable

[ertiop93]

Getting the following exception while trying to use lazy & livescroll mode together in datatable.

Code: Select all

java.lang.ArithmeticException: / by zero
	at org.primefaces.model.LazyDataModel.setRowIndex(LazyDataModel.java:62)
	at javax.faces.component.UIData.setRowIndexWithoutRowStatePreserved(UIData.java:485)
	at javax.faces.component.UIData.setRowIndex(UIData.java:473)
	at javax.faces.component.UIData.visitRows(UIData.java:2123)
	at javax.faces.component.UIData.visitTree(UIData.java:1437)
	at javax.faces.component.UIComponent.visitTree(UIComponent.java:1600)
	at javax.faces.component.UIComponent.visitTree(UIComponent.java:1600)
	at javax.faces.component.UIForm.visitTree(UIForm.java:344)
	at javax.faces.component.UIComponent.visitTree(UIComponent.java:1600)
	at javax.faces.component.UIComponent.visitTree(UIComponent.java:1600)
	at com.sun.faces.application.view.StateManagementStrategyImpl.saveView(StateManagementStrategyImpl.java:149)
	at com.sun.faces.application.StateManagerImpl.saveView(StateManagerImpl.java:133)
	at javax.faces.application.StateManager.getViewState(StateManager.java:553)
	at com.sun.faces.context.PartialViewContextImpl.renderState(PartialViewContextImpl.java:409)
	at com.sun.faces.context.PartialViewContextImpl.processPartial(PartialViewContextImpl.java:293)
	at javax.faces.context.PartialViewContextWrapper.processPartial(PartialViewContextWrapper.java:183)
	at javax.faces.component.UIViewRoot.encodeChildren(UIViewRoot.java:981)
	at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1756)
	at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:390)
	at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
	at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:121)
	at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
	at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
	at javax.faces.webapp.FacesServlet.service(FacesServlet.java:410)
	at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1534)

the xhtml code :

Code: Select all

<p:dataTable value="#{lazyloadBean.lazyList}" var="person" lazy="true" rows="28" liveScroll="true" scrollRows="15" scrollHeight="110" scrollable="true" >
        

the bean :

Code: Select all

@ManagedBean(name="lazyloadBean")
@RequestScoped
public class LazyloadBean {
    
    private LazyDataModel<QuickProfileIntro> lazyList;
    
    public LazyloadBean() {
        lazyList = new LazyDataModel<QuickProfileIntro>() {

            @Override
            public List<QuickProfileIntro> load(int first, int pageSize, String sortField, SortOrder sortOrder, Map<String, String> filters) {
                List<QuickProfileIntro> list = new ArrayList<QuickProfileIntro>(pageSize);
                // filling this list from DB...
                return list;
            }
        };
        lazyList.setRowCount(100000);
        
    }
    
    public LazyDataModel<QuickProfileIntro> getLazyList() {
        Easy.log("getLazyList called");
        return lazyList;
    }   

}

[cagatay.civici]

Lazy + live scroll not supported.

[ertiop93]

So basically that means that if I implement liveScroll with a huge dataset then the entire dataset would be read all in once but the client would get the results in pieces as he scroll down, right ?

So its just half the purpose solved!?

Am I getting it wrong ?

[ertiop93]

Is this feature going to come anytime in near future ? (in the roadmap ?)

[ulric2]

It also means that filters and sorts can't be applied because client doesn't know the whole dataset.

I really don't understand livescroll concept, as you said it's a half solution.
What is the sense of viewing a huge set of datas you cannot filter or sort ?
What about millions of records loaded on server and memory size?

Everything seems to be in place with lazymodel (serveur sort and filter) and client only display a small part.

Wouldn't it be possible in fixing the number of rows which is not known in scrolling dataTable and link the livescroll event like the change page event ?

[andyba]

I don't see the problem here, Lazy DataModel and LiveScrolling are pretty much incompatible with each other.

You should never be livescrolling through millions of records whereas LazyDataModel with Pagination is probably overkill for a couple of hundred.

Use the right tool for the job.

[smithh032772]

It also means that filters and sorts can't be applied because client doesn't know the whole dataset.

ulric2, I agree. That's why I had to add my own custom filterBy and sorting. See/click URL below and see my response at the very bottom.

viewtopic.php?f=3&t=6824

Well said, andyba!

I don't see the problem here, Lazy DataModel and LiveScrolling are pretty much incompatible with each other.

You should never be livescrolling through millions of records whereas LazyDataModel with Pagination is probably overkill for a couple of hundred.

Use the right tool for the job.

[ertiop93]

@Andyba: I agree you shouldn't livescroll on millions of records but why would you even like to retrieve 200 records during livescroll when you just need to show 10 of them initially ? That's increasing the load on the server as well as the database resources.

Isn't that a big disadvantage of current livescroll implementation ?

I don't see the problem here, Lazy DataModel and LiveScrolling are pretty much incompatible with each other.

You should never be livescrolling through millions of records whereas LazyDataModel with Pagination is probably overkill for a couple of hundred.

Use the right tool for the job.

[andyba]

@Andyba: I agree you shouldn't livescroll on millions of records but why would you even like to retrieve 200 records during livescroll when you just need to show 10 of them initially ? That's increasing the load on the server as well as the database resources.

Isn't that a big disadvantage of current livescroll implementation ?

I don't see the problem here, Lazy DataModel and LiveScrolling are pretty much incompatible with each other.

You should never be livescrolling through millions of records whereas LazyDataModel with Pagination is probably overkill for a couple of hundred.

Use the right tool for the job.

I agree with you in part however livescrolling is a feature that does have its uses.

- You don't lose rows of data from sight like you do with paging
- It is a natural way to load chunks of data from the server automatically

It is not good at things like more precise navigation - going to the tail of the data set will result in loading all the data for instance

It doesn't add more load to your Database. Server resources could become an issue however only when you are scrolling through a -lot- of records.

Livescrolling is a suitable alternative to paginated data where the set of data would not preclude the use of one or the other display method and where paging is not required or desired.

[smithh032772]

For others experiencing this error, I just provided a fix/workaround. See/click URL below and see my comment added:

http://code.google.com/p/primefaces/iss ... il?id=1544