Select element in CellList using SelectionModel or ListDataProvider

Question

I have used CellList for listing my data using ListDataProvider for managing the data and SelectionModel for selecting an element from CellList and generating events accordingly.

Now when i update or delete element using cellList.getList().set(index, bean) or cellList.getList().remove() it sucessfully do the operation. But after that it automatically selects the first record in CellList which i do not want.

Can anyone suggest how can i deselect the selected record in CellList?

Below is the code how i am initializing the selectionmodel and listprovider:

ListDataProvider<AppsBean> dataProvider = new ListDataProvider<AppsBean>();
CellList<AppsBean> appsCellList;
SingleSelectionModel<AppsBean>  singleSelectionModel;

ProvidesKey<AppsBean> keyProvider = new ProvidesKey<AppsBean>() {
        public Object getKey(AppsBean item) {
            // Always do a null check.
            return (item == null) ? null : item.getId();
        }
    };
    //here cell is the AbstractCell<AppsBean>    
    appsCellList = new CellList<AppsBean> (cell, keyProvider);
    dataProvider.addDataDisplay(appsCellList);
    appsCellList.setKeyboardSelectionPolicy(KeyboardSelectionPolicy.BOUND_TO_SELECTION);

    singleSelectionModel = new SingleSelectionModel<AppsBean>(keyProvider);
    appsCellList.setSelectionModel(singleSelectionModel);
    singleSelectionModel.addSelectionChangeHandler(new SelectionChangeEvent.Handler() {

        @Override
        public void onSelectionChange(SelectionChangeEvent event) {
            AppsBean selectedApp = singleSelectionModel.getSelectedObject();
            if (selectedApp != null)
                appsForm.fillApps(selectedApp);
        }
    });

When i am adding the new record:

dataProvider.getList().add(0, appsBean);

For updating the record:

AppsBean bean = singleSelectionModel.getSelectedObject();
dataProvider.getList().set(dataProvider.getList().indexOf(bean), appsBean);

And for delete:

int selectedIndex = dataProvider.getList().indexOf(singleSelectionModel.getSelectedObject());
dataProvider.getList().remove(selectedIndex);

Ümit · Accepted Answer · 2011-08-30T12:19:51.000

3

You will have to implement a KeyProvider in order to make sure that your selected DTO stays the same even when the object itself changes.
If you don't provide a KeyProvider it will probably use equals to compare the objects and if they change then you might run into problems.

ProvidesKey keyProvider = new ProvidesKey() {
    public Object getKey(Contact item) {
       //return the unique identifier for your DTO
       return (item == null) ? null : item.id;
    }
};

Then you have to initialize the CellTable and selectionModel with this keyProvider

 CellList cellList = new CellList(new ContactCell(),keyProvider);

 SelectionModel selectionModel = new SingleSelectionModel(keyProvider);
 cellList.setSelectionModel(selectionModel);

Update De-selecting a selected object works like this:

 Object obj  = selectionModel.getSelectedObject();
 if (obj != null) {
     selectionModel.setSelected(obj,false);
 }

edited Aug 30 '11 at 12:19

answered Aug 29 '11 at 07:23

Ümit

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Its working for cellList.getList().set(index, bean). Thanks. But when i do cellList.getList().remove(index) it automatically select the first record in the list. How can i deselect the current selection using code? – vbjain Aug 30 '11 at 09:24
`Object obj = selectionModel.getSelectedObject(); if (obj != null) { selectionModel.setSelected(obj,false); }` is working fine with one issue. The object is getting deselect perfectly. But when i try to select it again without selecting any other object then i am not able to select it. How can i do it? – vbjain Aug 31 '11 at 08:48
I am not sure what you mean. Are you selecting the CellList entry programmatically or by clicking on it? What happens exactly? Does it work if you select another entry? – Ümit Aug 31 '11 at 11:55
For example, i have 3 objects in list. I selected the 2nd entry and then programmatically calling deselect it as the above code provided by you. Thats working fine. Now manually i click on 2nd entry itself but no selection event being fired and nothing get happened. Then if i select first entry its working fine. And now again selecting the 2nd entry then also its working fine. – vbjain Aug 31 '11 at 12:12
hmm that sounds like a bug to me. Which GWT version are you using and did you add a SelectionChangeHandler? – Ümit Aug 31 '11 at 12:47
I am using GWT 2.3.0. And yes i do add SelectionChangeHandler on SelectionModel. – vbjain Aug 31 '11 at 13:33
Hmm shouldn't happen. I will try to reproduce it. Maybe you can update your question with the code for the SelectionChangeHandler and how you add the selectionModel to the CellList. – Ümit Aug 31 '11 at 13:47
Ok i have added the code. Please let me know what else is required. @timeu i have updated the add, edit, delete calls also. – vbjain Aug 31 '11 at 14:15
Ok thanks I haven't tried the code myself but I checked the issue tracker of GWT and it seems there is a bug entry for that error. See here: http://code.google.com/p/google-web-toolkit/issues/detail?id=5227&q=CellList%20selectionModel&colspec=ID%20Type%20Status%20Owner%20Milestone%20Summary%20Stars. It seems a workaround is to call ListDataProvider.refresh() befor you call setSelected() – Ümit Sep 01 '11 at 09:22

score 2 · Answer 2 · answered Jun 17 '13 at 20:09

I was having the same problem with GWT 2.5.1. Deselecting the object programmatically was not working: the next row was selected when I deleted the object from the list of the data provider (and the deselection threw another unwanted event). The solution was to do:

selectionModel.getSelectedSet().clear();

score 0 · Answer 3 · edited Sep 19 '14 at 06:28

I had the same issue: @vbjain wrote: Now when I update or delete element using cellList.getList().set(index, bean) or cellList.getList().remove() it sucessfully do the operation. But after that it automatically selects the first record in CellList which I do not want.

After hours of googling I found, that it happend when keyboard policy is:

KeyboardSelectionPolicy.BOUND_TO_SELECTION

If you select KeyboardSelectionPolicy.DISABLED, you can not list up/down by keyboard, but the issue with selection of first row is resolved.

Select element in CellList using SelectionModel or ListDataProvider

3 Answers3

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