[CAY-847] Expression NULL handling

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0
• Fix Version/s: 3.0M2
• Component/s: Core Library
• Assignee: Andrus Adamchik
• Reporter: Andrus Adamchik
• Created: 14/Aug/07 21:34
• Updated: 09/Nov/08 01:07
• Resolved: 14/Aug/07 21:57

Description

Consider the following unit test:

public void testNullParameters()

{ Expression e = ExpressionFactory.matchExp("X", null); assertEquals("X = null", e.toString()); e = Expression.fromString("X = $x").expWithParameters( Collections.singletonMap("x", null)); assertEquals("X = null", e.toString()); }

The first assertion succeeds, while the second throws an NPE:

java.lang.NullPointerException
at org.apache.cayenne.exp.parser.SimpleNode.encodeAsString(SimpleNode.java:184)
at org.apache.cayenne.exp.Expression.toString(Expression.java:549)
at org.apache.cayenne.exp.ExpressionTest.testNullParameters(ExpressionTest.java:42)

Turns out the difference is in wrapping of the NULL parameter in ASTScalar in the first case, and leaving a bare NULL in the second. I guess this requires two-part fix:

1. Ensure that NULL's are wrapped in ASTScalar in 'expWithParameters'
2. Null checks in encodeAsString (just in case)