Dear all,
I just finished to struggle with the display of nullable Long or Integer
values. I am using Primefaces 5.0.1 / MyFaces 2.2.4 / OpenWebBeans 1.2.2
/ Tomcat 7.0.39.
Those values are the result of the evaluation of EL expressions that I
create with the following function :
public static ValueExpression createValueExpression(String
expression, Class clazz) {
FacesContext fc = FacesContext.getCurrentInstance();
ELContext elContext = fc.getELContext();
FacesELContext felContext = (FacesELContext)fc.getELContext();
SenatFunctionMapper sfm = SenatFunctionMapper.getInstance();
felContext.setFunctionMapper(sfm);
ExpressionFactory expFactory =
fc.getApplication().getExpressionFactory();
ValueExpression ret = null;
if(clazz==null) {
clazz = Object.class;
}
try {
ret = expFactory.createValueExpression(elContext,
expression, clazz);
} catch (ELException ex) {
log.fatal("Erreur de compilation de l'expression EL :
'" + expression + "'", ex);
}
return ret;
}
Until now, I created those value expressions with the real expected
class as the third parameter of ExpressionFactory#createValueExpression.
The name of this parameter is "expectedType", so it seems logical to me
to provide the best information I had. So, I provided
java.lang.Integer.class or java.lang.Long.class, etc.
But when I do that, null values are displayed as 0, either with
h:inputText (standard MyFaces control) or p:inputText (PrimeFaces version).
The reason being that
org.apache.el.ValueExpressionImpl#getValue
is implemented the following way
@Override
public Object getValue(ELContext context) throws
PropertyNotFoundException,
ELException {
EvaluationContext ctx = new EvaluationContext(context,
this.fnMapper,
this.varMapper);
Object value = this.getNode().getValue(ctx);
if (this.expectedType != null) {
return ELSupport.coerceToType(value, this.expectedType);
}
return value;
}
and that ELSupport.coerceToType of a Long or Integer null value is
defined as... 0
As those type are numeric, coerceToType calls coerceToNumber, which
starts with :
public static final Number coerceToNumber(final Object obj,
final Class<?> type) throws ELException {
if (obj == null || "".equals(obj)) {
return coerceToNumber(ZERO, type);
}
...
}
thus, the ZERO value.
For the time being, I solved my «problem» by passing a null third
parameter to ExpressionFactory#createValueExpression. It works. It has
no apparent drawbacks. But I don't get the logic of it. Should'nt
ELSupport#coerceToNumber handles this differently ?
Thanks in advance for your explanations,
Ludovic
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