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https://issues.apache.org/jira/browse/JEXL-327?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Henri Biestro closed JEXL-327.
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> 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
> Priority: Trivial
> Fix For: 3.2
>
>
> 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".
>
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