Martin Makundi created WICKET-5772:
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Summary: LoadableDetachableModel caches null value if load()
fails, bug in getObject() {attached = true;}
Key: WICKET-5772
URL: https://issues.apache.org/jira/browse/WICKET-5772
Project: Wicket
Issue Type: Bug
Components: wicket
Affects Versions: 7.0.0-M4, 6.18.0, 1.4.23
Reporter: Martin Makundi
If you have a LoadableDetachableModel whose load() operation fails at an
instance, the LoadableDetachableModel will cache null value because
getObject() method sets attached = true; before load() invocation has returned.
This results in methods trusting LoadableDetachableModel using the null value
for their operations which is logically incorrect as null might not be a legal
value at all. Such behavior would result in unexpected difficult-to-debug
behavior in depending components.
Easy fix:
Move:
attached = true;
after line:
transientModelObject = load();
Test case:
/**
* LoadableDetachableModel must not return null as an attached value if load()
* fails.
*/
public void testWhenLoadFails() {
final LoadableDetachableModel<Void> loadableDetachableModel = new
LoadableDetachableModel<Void>() {
/**
* @see org.apache.wicket.model.LoadableDetachableModel#load()
*/
@Override
protected Void load() {
throw new UnsupportedOperationException("Let's assume this fails for
some reason.");
}
};
try {
loadableDetachableModel.getObject();
fail(UnsupportedOperationException.class + " expected.");
} catch (final UnsupportedOperationException e) {
LoggerFactory.getLogger(LoadableDetachableModel.class).debug("Expected
behavior due to " + UnsupportedOperationException.class);
}
try {
assertNotSame(LoadableDetachableModel.class + " should not return null if
it's load() has failed\n", null,
loadableDetachableModel.getObject());
} catch (final UnsupportedOperationException e) {
LoggerFactory.getLogger(LoadableDetachableModel.class).debug("Expected
behavior due to " + UnsupportedOperationException.class);
}
}
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