使用SelectionModel或ListDataProvider在CellList中选择元素 [英] Select element in CellList using SelectionModel or ListDataProvider

问题描述

我已经使用CellList来列出我的数据，使用ListDataProvider管理数据，SelectionModel从CellList中选择一个元素并相应地生成事件。 现在，当我更新或使用cellList.getList（）.set（index，bean）或cellList.getList（）。remove（）它可以成功执行操作。但在此之后，它会自动选择我不想要的CellList中的第一条记录。

任何人都可以建议如何取消选中CellList中的所选记录吗？

以下是我如何初始化selectionmodel和listprovider的代码：

  ListDataProvider< AppsBean> ; dataProvider = new ListDataProvider< AppsBean>（）; 
 CellList< AppsBean> appsCellList; 
 SingleSelectionModel< AppsBean> singleSelectionModel; 
 
 ProvideKey< AppsBean> keyProvider = new ProvideKey< AppsBean>（）{
 public Object getKey（AppsBean item）{
 //总是进行空检查。 
 return（item == null）？ null：item.getId（）; 
} 
}; 
 //这里cell是AbstractCell< AppsBean> 
 appsCellList =新的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（）{
 $ b @Override 
 public void onSelectionChange（SelectionChangeEvent event）{
 AppsBean selectedApp = singleSelectionModel.getSelectedObject（）; 
 if（selectedApp！= null）
 appsForm.fillApps（selectedApp）; 
} 
}）; 
  

当我添加新记录时：

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

更新记录：

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

并用于删除：

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

解决方案

您必须实现一个KeyProvider才能使确保您选择的DTO即使在对象本身发生变化时也保持不变。

如果您没有提供KeyProvider，它可能会使用equals来比较这些对象，如果它们发生变化，那么您可能会遇到问题。

  ProvideKey keyProvider = new ProvideKey（）{
 public Object getKey（Contact item）{
 //返回您的DTO 
 return（item == null）的唯一标识符？ null：item.id; 
} 
}; 
  

然后你必须用这个keyProvider初始化CellTable和selectionModel

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

更新
取消所选对象的作用如下：

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

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);

解决方案

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);
 }

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