[GitHub] [calcite] vlsi commented on a change in pull request #2272: [CALCITE-4409] Improve exception when RelBuilder tries to create a field on a non-struct expression

[GitBox <gi...@apache.org>]

vlsi commented on a change in pull request #2272:
URL: https://github.com/apache/calcite/pull/2272#discussion_r528563712



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File path: core/src/main/java/org/apache/calcite/tools/RelBuilder.java
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@@ -495,6 +495,10 @@ public RexNode field(int inputCount, String alias, String fieldName) {
 
   /** Returns a reference to a given field of a record-valued expression. */
   public RexNode field(RexNode e, String name) {
+    if (!e.getType().isStruct()) {
+      throw new IllegalArgumentException("Requested field " + name + " in non-struct expression "
+          + e.toString() + " (type: " + e.getType() + ")");
+    }

Review comment:
       I believe this check should be moved to `org.apache.calcite.rel.type.RelDataTypeImpl#getField`
   Then all uses of `RelDataTypeImpl#getField` would get the proper exception rather than NPE.




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