[FLINK-15266][table-planner-blink] Fix NPE for code generated CASE WH…

…EN operator in blink planner (#10594)
apache · Dec 20, 2019 · 5f86f2d · 5f86f2d
1 parent b692d10
commit 5f86f2d
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Showing 2 changed files with 10 additions and 3 deletions.
diff --git a/...link/src/main/scala/org/apache/flink/table/planner/codegen/calls/ScalarOperatorGens.scala b/...link/src/main/scala/org/apache/flink/table/planner/codegen/calls/ScalarOperatorGens.scala
@@ -1279,21 +1279,26 @@ object ScalarOperatorGens {
 
       val Seq(resultTerm, nullTerm) = newNames("result", "isNull")
       val resultTypeTerm = primitiveTypeTermForType(resultType)
+      val defaultValue = primitiveDefaultValue(resultType)
 
       val operatorCode = if (ctx.nullCheck) {
         s"""
            |${condition.code}
-           |$resultTypeTerm $resultTerm;
+           |$resultTypeTerm $resultTerm = $defaultValue;
            |boolean $nullTerm;
            |if (${condition.resultTerm}) {
            |  ${trueAction.code}
-           |  $resultTerm = ${trueAction.resultTerm};
            |  $nullTerm = ${trueAction.nullTerm};
+           |  if (!$nullTerm) {
+           |    $resultTerm = ${trueAction.resultTerm};
+           |  }
            |}
            |else {
            |  ${falseAction.code}
-           |  $resultTerm = ${falseAction.resultTerm};
            |  $nullTerm = ${falseAction.nullTerm};
+           |  if (!$nullTerm) {
+           |    $resultTerm = ${falseAction.resultTerm};
+           |  }
            |}
            |""".stripMargin.trim
       }

diff --git a/...blink/src/test/scala/org/apache/flink/table/planner/expressions/ScalarOperatorsTest.scala b/...blink/src/test/scala/org/apache/flink/table/planner/expressions/ScalarOperatorsTest.scala
@@ -122,5 +122,7 @@ class ScalarOperatorsTest extends ScalarOperatorsTestBase {
     testSqlApi("CASE f7 WHEN 1 THEN 11 WHEN 2 THEN 4 ELSE NULL END", "null")
     testSqlApi("CASE 42 WHEN 1 THEN 'a' WHEN 2 THEN 'bcd' END", "null")
     testSqlApi("CASE 1 WHEN 1 THEN true WHEN 2 THEN false ELSE NULL END", "true")
+
+    testSqlApi("CASE WHEN f2 = 1 THEN CAST('' as INT) ELSE 0 END", "null")
   }
 }