Package org.apache.wicket.markup.repeater.data

Interface IDataProvider<T>

  • Type Parameters:
    T -
    All Superinterfaces:
    org.apache.wicket.util.io.IClusterable, IDetachable, Serializable
    All Known Implementing Classes:
    EmptyDataProvider, ListDataProvider
    public interface IDataProvider<T>
extends IDetachable
    Interface used to provide data to data views. Example: 
     class UsersProvider implements IDataProvider
 {
 
        public Iterator iterator(long first, long count)
        {
                ((MyApplication)Application.get()).getUserDao().iterator(first, count);
        }
 
        public long size()
        {
                ((MyApplication)Application.get()).getUserDao().getCount();
        }
 
        public IModel model(Object object)
        {
                return new DetachableUserModel((User)object);
        }
 }
    You can use the IDetachable.detach() method for cleaning up your IDataProvider instance. So that you can do one query that returns both the size and the values if your dataset is small enough the be able to do that.
    Author:
    Igor Vaynberg (ivaynberg)
    See Also:
    IDetachable, DataViewBase, DataView, GridView

    • Method Detail

      • iterator

        Iterator<? extends T> iterator​(long first,
                               long count)
        Gets an iterator for the subset of total data
        Parameters:
        first - first row of data
        count - minimum number of elements to retrieve
        Returns:
        iterator capable of iterating over {first, first+count} items

      • size

        long size()
        Gets total number of items in the collection represented by the DataProvider
        Returns:
        total item count

      • model

        IModel<T> model​(T object)
        Callback used by the consumer of this data provider to wrap objects retrieved from iterator(long, long) with a model (usually a detachable one).
        Parameters:
        object - the object that needs to be wrapped
        Returns:
        the model representation of the object

      • detach

        default void detach()
        Description copied from interface: IDetachable
        Detaches model after use. This is generally used to null out transient references that can be re-attached later.
        Specified by:
        detach in interface IDetachable