Package org.apache.wicket.markup.html.form

Class LambdaChoiceRenderer<T>

  • Type Parameters:
    T - The model object type
    All Implemented Interfaces:
    Serializable, IChoiceRenderer<T>, IDetachable, IClusterable
    public class LambdaChoiceRenderer<T>
extends Object
implements IChoiceRenderer<T>
    Renders one choice. Separates the 'id' values used for internal representation from 'display values' which are the values shown to the user of components that use this renderer.

    Usage: 

     new DropDownChoice<User>("users", new Model<User>(selectedUser), listOfUsers,
        new LambdaChoiceRenderer<User>(User::getName))

    creates a DropDownChoice of users and the display value will be looked up by function (User::getName) and the id the index of the object in the ListOfUsers 

     new DropDownChoice<User>("users", new Model<User>(selectedUser), listOfUsers,
        new LambdaChoiceRenderer<User>(User::getName, User::getId))

    creates a DropDownChoice of users and the display value will be looked up by function (User::getName) and the id will be looked up by the function (User::getId)

    See Also:
    Serialized Form

    • Constructor Detail

      • LambdaChoiceRenderer

        public LambdaChoiceRenderer()
        Constructor.

        When you use this constructor, the display value will be determined by calling toString() on the list object, and the id will be based on the list index. the id value will be the index

      • LambdaChoiceRenderer

        public LambdaChoiceRenderer​(org.danekja.java.util.function.serializable.SerializableFunction<T,​?> displayExpression)
        Constructor.

        When you use this constructor, the display value will be determined by executing the given function on the list object, and the id will be based on the list index. The display value will be calculated by the given function

        Parameters:
        displayExpression - A function to get the display value

      • LambdaChoiceRenderer

        public LambdaChoiceRenderer​(org.danekja.java.util.function.serializable.SerializableFunction<T,​?> displayExpression,
                            org.danekja.java.util.function.serializable.SerializableFunction<T,​?> idExpression)
        Constructor.

        When you use this constructor, both the id and the display value will be determined by executing the given functions on the list object.

        Parameters:
        displayExpression - A function to get the display value
        idExpression - A function to get the id value

    • Method Detail

      • getIdValue

        public String getIdValue​(T object,
                         int index)
        Description copied from interface: IChoiceRenderer
        This method is called to get the id value of an object (used as the value attribute of a choice element) The id can be extracted from the object like a primary key, or if the list is stable you could just return a toString of the index.

        Note that the given index can be -1 if the object in question is not contained in the available choices.

        Specified by:
        getIdValue in interface IChoiceRenderer<T>
        Parameters:
        object - The object for which the id should be generated
        index - The index of the object in the choices list.
        Returns:
        String