GWT: how can i add/remove a button in a celltable on the go - gwt

Question

I have this button cell in my CellTable
ButtonCell reListCell = new ButtonCell();
reListColumn = new Column<EmployerJobs, String>(reListCell) {
#Override
public String getValue(EmployerJobs object) {
return "ReList";
}
};
ctJobs.addColumn(reListColumn,
EmployerDashBoardConstants.EMPTYHEADERCOLUMN);
but i only want this cell to be appear if the below condition pass
public void getDateDiff(final EmployerJobs object) {
rpcService.getDateDiff(object.getJobValidDate(), new AsyncCallback<Boolean>() {
public void onFailure(Throwable caught) {
}
public void onSuccess(Boolean jobExpired) {
if(jobExpired) {
// HERE I WANT TO SHOW MY RELISTCELL, means if the job is expired only then
// there will be a button showing relist would be appear in that row ,for
// the jobs which are not expired NO button should appear..
}
}
});
}
how can i achieve this?
thanks

Answer 1

I agree with DTing.
Quering the backend for each cell/row is not really efficient.
I would rather put the info (jobExpired) into your EmployerJobs class and transfer the info when you request the list of your EmployerJobs to be displayed in your CellTable.
You can update the list periodically to account for changes (see the expenses sample on how to do that).
But to your initial question (hiding the cell). There are two solutions:
Use an ActionCell and override the render method.
ActionCell:
ActionCell<EmployerJobs> reListCell = new ActionCell<EmployerJobs>("ReList",
new ActionCell.Delegate<EmployerJobs>() {
#Override
public void execute(EmployerJobs object) {
// code to be executed
}
})
{
#Override
public void render(Cell.Context context,EmployerJobs value,SafeHtmlBuilder sb) {
if (value.isJobExpired()) // isJobExpired returns the field jobExpired.
super.render(context,value,sb);
}
};
reListColumn = new Column<EmployerJobs, EmployerJobs>(reListCell) {
#Override
public String getValue(EmployerJobs object) {
return object;
}
};
ctJobs.addColumn(reListColumn,
EmployerDashBoardConstants.EMPTYHEADERCOLUMN);
Use a ButtonCell and override the render method of your Column.
ButtonCell:
ButtonCell reListCell = new ButtonCell();
reListColumn = new Column<EmployerJobs, String>(reListCell) {
#Override
public String getValue(EmployerJobs object) {
return "ReList";
}
#Override
public void render(Cell.Context context,EmployerJobs object,SafeHtmlBuilder sb) {
if (value.isJobExpired()) // isJobExpired returns the field jobExpired.
super.render(context,value,sb);
}
};
ctJobs.addColumn(reListColumn,
EmployerDashBoardConstants.EMPTYHEADERCOLUMN);

Answer 2

Just tried Umit solution #2 ButtonCell. It works!
To link an specific action to the button, reListColumn.setFieldUpdater(new FieldUpdater....
would be needed

Answer 3

I tried ButtonCell solution too. But if you click in a cell who as no button then an error on client side occur:
com.google.gwt.core.client.JavaScriptException: (TypeError) #com.google.gwt.core.client.impl.Impl::apply(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)([JavaScript object(445), JavaScript object(240), JavaScript object(637)]): parent is null
So I added this to override the Event and avoid Event if I want:
#Override
public void onBrowserEvent(com.google.gwt.cell.client.Cell.Context context,
Element parent, YourObject object, NativeEvent event) {
if (object.isCompleted())
super.onBrowserEvent( context, parent, object, event);
}
I don't know if it's the better way to do it but it works.