Re: CellTable, this.focus is not a function

[Thomas Broyer]

On Thursday, November 29, 2012 1:54:38 PM UTC+1, Piotr Kopeć wrote:

Hi All
As workaround for editing NULL values in CellTable i've extended Column

Why? That's the job of cells, not columns. If a cell doesn't allow editing a 'null', then extend/fork that cell instead; or give it a non-null value. This is exactly what the workarounds at https://code.google.com/p/google-web-toolkit/issues/detail?id=5791 are doing.

 

All works nice till use of SingleSelectionModel
With selection model editing null values goes random, some values can be edited, some not, after few tries selection model stops responding
Related exception stack trace below:

[ERROR] com.google.gwt.core.client.JavaScriptException: (TypeError) @com.google.gwt.dom.client.Element::focus()([]): this.focus is not a function
[ERROR]     at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:249)
[ERROR]     at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
[ERROR]     at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:570)
[ERROR]     at com.google.gwt.dev.shell.ModuleSpace.invokeNativeVoid(ModuleSpace.java:298)
[ERROR]     at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeVoid(JavaScriptHost.java:107)
[ERROR]     at com.google.gwt.dom.client.Element$.focus$(Element.java)
[ERROR]     at com.google.gwt.cell.client.EditTextCell.resetFocus(EditTextCell.java:240)
[ERROR]     at com.google.gwt.cell.client.EditTextCell.resetFocus(EditTextCell.java:1)

 

[ERROR]     at com.google.gwt.user.cellview.client.AbstractCellTable.resetFocusOnCellImpl(AbstractCellTable.java:2575)
[ERROR]     at com.google.gwt.user.cellview.client.AbstractCellTable.resetFocusOnCell(AbstractCellTable.java:2193)
[ERROR]     at com.google.gwt.user.cellview.client.AbstractHasData$View$1.execute(AbstractHasData.java:290)
[ERROR]     at com.google.gwt.user.cellview.client.CellBasedWidgetImpl.resetFocus(CellBasedWidgetImpl.java:102)
[ERROR]     at com.google.gwt.user.cellview.client.AbstractHasData$View.resetFocus(AbstractHasData.java:287)
[ERROR]     at com.google.gwt.user.cellview.client.HasDataPresenter.resolvePendingState(HasDataPresenter.java:1374)
[ERROR]     at com.google.gwt.user.cellview.client.HasDataPresenter.access$3(HasDataPresenter.java:1062)
[ERROR]     at com.google.gwt.user.cellview.client.HasDataPresenter$2.execute(HasDataPresenter.java:984)
[ERROR]     at com.google.gwt.core.client.impl.SchedulerImpl$Task$.executeScheduled$(SchedulerImpl.java:50)
[ERROR]     at com.google.gwt.core.client.impl.SchedulerImpl.runScheduledTasks(SchedulerImpl.java:228)
[ERROR]     at com.google.gwt.core.client.impl.SchedulerImpl.flushFinallyCommands(SchedulerImpl.java:327)
[ERROR]     at com.google.gwt.core.client.impl.Impl.exit(Impl.java:266)
[ERROR]     at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:257)
[ERROR]     at sun.reflect.GeneratedMethodAccessor286.invoke(Unknown Source)
[ERROR]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[ERROR]     at java.lang.reflect.Method.invoke(Method.java:601)
[ERROR]     at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
[ERROR]     at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
[ERROR]     at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
[ERROR]     at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:293)
[ERROR]     at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:547)
[ERROR]     at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:364)
[ERROR]     at java.lang.Thread.run(Thread.java:722)

Example class for reproducing exception below:

public class GwtBugTest0 {

    // Entity
    class Man {
        String name;
        Date birth;
    }

    // column that renders [NONE] for null and is updater, also gives initial value for updater
    abstract class NoneColumn<T, V> extends Column<T, V> implements FieldUpdater<T, V> {
        V def;

        public NoneColumn(Cell<V> cell, V def) {
            super(cell);
            this.def = def;
            setFieldUpdater(this);
        }

        @Override
        public V getValue(T object) {
            V ret = getRawValue(object);
            return ret == null ? def : ret;
        }

        @Override
        public void render(Context context, T object, SafeHtmlBuilder sb) {
            if (getRawValue(object) == null)
                sb.appendHtmlConstant("[NONE]");
            else
                super.render(context, object, sb);
        }

Your problem is that you're not calling the cell's render() when the value is null (in this case, getValue() is not called so your default value is not really needed), so when the CellTable tries to set the focus back to the cell by calling the Column's Cell's resetFocus, the Cell (an EditTextCell here) doesn't find back its element (because it looks at something that it didn't generate) and ends up calling focus() on the wrong object.

Remove that render() override, and instead move that code into your own cell. Either extend EditTextCell or wrap it in your own cell, and handle resetFocus accordingly. It might be easier to fork and patch EditTextcell though (and contribute the patch back for inclusion in GWT proper)

[Piotr Kopeć]

Thank you Thomas,
The column gave me opportunity to easily ~cheat, to make it work without rewriting whole Cell classes( private members)

Your problem is that you're not calling the cell's render() when the value is null (in this case, getValue() is not called so your default value is not really needed), so when the CellTable tries to set the focus back to the cell by calling the Column's Cell's resetFocus, the Cell (an EditTextCell here) doesn't find back its element (because it looks at something that it didn't generate) and ends up calling focus() on the wrong object.

Thanks for that! (default value was used as initial value for DatePickerCell when real value is null, also was used to show InputField if text value was null).
As I wrote, this solution works fine without SingleSelectionModel. But I agree that probably best would be to fork Cells and code desired behaviour but with my current GWT knowledge- it shurely wouldn't be contributed as patch :D.
As a temporary solution I switched to CellList with DateBox but it isn't even half pretty as CellTable so... I have to go deeper into Cells internals.

PS. Sorry for delay, I wasn't notified abt. your reply