IPropertySelectionModel


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2   //
3   // Licensed under the Apache License, Version 2.0 (the "License");
4   // you may not use this file except in compliance with the License.
5   // You may obtain a copy of the License at
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9   // Unless required by applicable law or agreed to in writing, software
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12  // See the License for the specific language governing permissions and
13  // limitations under the License.
14  
15  package org.apache.tapestry.form;
16  
17  /**
18   * Used by a {@link PropertySelection} to provide labels for options.
19   * <p>
20   * The component requires three different representations of each option:
21   * <ul>
22   * <li>The option value, the server-side Java object that will eventually be assigned to a property
23   * <li>The label, a string which is incorprated into the HTML to identify the option to the user
24   * <li>The value, a client-side string which is used to represent the option as the value of the
25   * &lt;option&gt; or &lt;input type=radio&gt; generated by the {@link PropertySelection}.
26   * </ul>
27   * <p>
28   * The option is usually a string, a primitive value, or some kind of business object. The label is
29   * often a property of the option object (for example, for a list of customers, it could be the
30   * customer name).
31   * <p>
32   * It should be easy to convert between the value and the option. It may simply be an index into an
33   * array. For business objects, it is often the primary key of the object, expressed as a String.
34   * 
35   * @author Howard Lewis Ship
36   */
37  
38  public interface IPropertySelectionModel
39  {
40      /**
41       * Returns the number of possible options.
42       */
43  
44      public int getOptionCount();
45  
46      /**
47       * Returns one possible option that will be assigned to the server-side property.
48       */
49  
50      public Object   getOption(int index);
51  
52      /**
53       * Returns the label for an option. It is the responsibility of the adaptor to make this value
54       * localized.
55       */
56  
57      public String   getLabel(int index);
58  
59      /**
60       * Returns a String used to represent the option in the HTML (as the value of an &lt;option&gt;
61       * or &lt;input type=radio&gt;. This value is not visible to the user, and is often an index
62       * into an array.
63       */
64  
65      public String   getValue(int index);
66  
67      /**
68       * Returns the option corresponding to a value. This is used when interpreting submitted form
69       * parameters.
70       */
71  
72      public Object   translateValue(String   value);
73  }
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