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JavaServer Faces by Hans Bergsten

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Converting Between Model and View Data Formats

Adding the value binding expression takes us one step closer to a real application, but we’re not done yet. First, note that the date fields are too short to show the dates in the format in which they are presented. Also, if you try to submit the form, error messages regarding the dates are displayed at the top of the page. The error messages are displayed by the <h:messages> action I added at the top in Example 6-3, which I’ll get back to in the next chapter.

The reason for the error messages is that the value is sent to the application as a string (an HTTP request parameter is always a string), but the data type for the from and to properties is java.util.Date. JSF takes care of conversion between strings and simple data types—numbers and Booleans—all by itself, but a date can be written in many different ways, so we need to give JSF a clue about how to interpret a string representing a date. Example 6-4 shows you how this is done.

Example 6-4. Filtering criteria form with date converters (expense/stage3/filterArea.jsp)
<%@ page contentType="text/html" %>
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>

<f:view>
  <h:messages layout="table"/>
  <h:form>
    From: 
    <h:inputText size="8" value="#{reportHandler.from}">
      <f:convertDateTime dateStyle="short" />
    </h:inputText>
    <br>
    To: 
    <h:inputText size="8" value="#{reportHandler.to}">
      <f:convertDateTime dateStyle="short" />

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