David Costanzo created JEXL-327:
-----------------------------------
Summary: map[null] does not work in assignment context
Key: JEXL-327
URL: https://issues.apache.org/jira/browse/JEXL-327
Project: Commons JEXL
Issue Type: Bug
Affects Versions: 3.1
Reporter: David Costanzo
In JEXL, you can create a map with a null key by using a map literal and you
can get the value associated with a null key. However, you can't assign a
value to a null key, as in
{code:java}
map[null] = 'bar'{code}
This asymmetry is weird and might be an oversight.
*Impact:*
This has not blocked us from doing anything, so *the impact nearly zero*. It's
something I found while writing unit tests for my application, but it does not
impact my users. I'm mostly reporting it as a "language weirdness", in case
the JEXL developers care.
That said, we _do_ use null keys in maps. In my domain (working with data from
clinical trials), a null numeric value means "missing", which is a valid value.
Our JEXL programmers implement "switch" statements using a map, so you might
see an expression that translates a coded variable named "DMSEX" into an
English description like:
{code:java}
{
null : "Unknown",
1 : "MALE",
2 : "FEMALE"
}[DMSEX]{code}
Fortunately, this works as expected. This bug only prevents us from building
the lookup map programmatically, but we prefer using a literal, anyway.
*Steps to Reproduce:*
{code:java}
@Test
public void testSetNullKey() throws IOException {
JexlEngine jexl = new JexlBuilder().create();
JexlContext jc = new MapContext();
JexlExpression expression1 = jexl.createExpression(
"(function () {\n" +
" var map = {null : 'foo'};\n" +
" map[null] = 'bar';\n" +
" return map[null];\n" +
"})()");
// JEXL 3.1, throws JexlException$Property "unsolvable property
'<?>.<null>'"
// JEXL 3.2, throws JexlException$Property "undefined property '<?>.<null>'"
Object o1 = expression1.evaluate(jc);
Assert.assertEquals("bar", o1);
}{code}
*What Happens:*
JEXL throws a JexlException.Property exception when it tries to evaluate
"{{map[null] = 'bar'}}".
*Expected Result:*
"{{map[null] = 'bar'}}" changes the null key's value from "foo" to "bar" and
the function returns "bar".
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
