How to handle exceptions in a FacesConverter? - validation

Question

When the date format is not correct (for example when I manually post 13,02,2018 instead of 13.02.2018 and also other incorrect dates such as 13.02.999) the app crashes. How can I fix it? (the manual input is important, i can`t just disable it).
XHTML:
<rich:calendar enableManualInput="true" datePattern="dd.MM.yyyy"
value="#{myBean.data.myDate}">
<f:converter converterId="mydate"/>
</rich:calendar>
Converter:
#FacesConverter("mydate")
public class LocalDateConverter implements Converter {
private static final DateTimeFormatter formatter;
static {
formatter = DateTimeFormatter.ofPattern("dd.MM.yyyy");
formatter.withLocale(new Locale("ru"));
}
#Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
return LocalDate.parse(value, formatter);
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
if (value == null) {
return "";
} else if (value instanceof LocalDate) {
return ((LocalDate) value).format(formatter);
} else if (value instanceof LocalDateTime) {
return ((LocalDateTime) value).format(formatter);
} else {
throw new IllegalArgumentException("Value is not java.time.LocaleDate");
}
}

Answer 1

Converters should throw a ConverterException which can contain a FacesMessage. This message can be displayed on your XHTML page, near the input component that caused the exception using <h:message for="inputComponentId"/>.
The problem occurs in your getAsObject method. There you should catch the DateTimeParseException exception and throw a ConverterException:
try {
return LocalDate.parse(value, formatter);
}
catch (DateTimeParseException ex) {
throw new ConverterException(new FacesMessage("Invalid date: " + value));
}
See also:
https://docs.oracle.com/javaee/7/tutorial/jsf-custom010.htm
How to use java.time.ZonedDateTime / LocalDateTime in p:calendar

Answer 2

You don't need converter at all. Simply include label attribute in rich:calendar component and let system figure out if value is correct. Example:
<h:outputLabel for="programStartDate" value="#{msg.programStartDate}" />
<rich:calendar id="programStartDate" value="#{program.programStartDate}"
label="#{msg.programStartDate}" inputStyle="width: 100px;"
datePattern="#{referenceData.defaultDatePattern}"
timeZone="#{referenceData.timezone}"
enableManualInput="true" popup="true" required="true" />

Answer 3

use a try catch and catch the exception so it doesn't crash but continue without allowing the exception to crash your program
#FacesConverter("mydate")
public class LocalDateConverter implements Converter
{
private static final DateTimeFormatter formatter;
static {
formatter = DateTimeFormatter.ofPattern("dd.MM.yyyy");
formatter.withLocale(new Locale("ru"));
}
#Override
public Object getAsObject(FacesContext context, UIComponent component, String value)
{
return LocalDate.parse(value, formatter);
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object value)
{
try
{
if (value == null)
{
return "";
}
else if (value instanceof LocalDate) {
return ((LocalDate)value).format(formatter);
} else if (value instanceof LocalDateTime) {
return ((LocalDateTime)value).format(formatter);
} else {
throw new IllegalArgumentException("Value is not java.time.LocaleDate");
}
}
catch (Exception)
{
return "SOME DEFAULT DATE";
}
}
}