fqaiser94 commented on a change in pull request #27066:
URL: https://github.com/apache/spark/pull/27066#discussion_r464177138
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File path: sql/core/src/main/scala/org/apache/spark/sql/Column.scala
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@@ -871,6 +871,72 @@ class Column(val expr: Expression) extends Logging {
*/
def getItem(key: Any): Column = withExpr { UnresolvedExtractValue(expr,
Literal(key)) }
+ // scalastyle:off line.size.limit
+ /**
+ * An expression that adds/replaces field in `StructType` by name.
+ *
+ * {{{
+ * val df = sql("SELECT named_struct('a', 1, 'b', 2) struct_col")
+ * df.select($"struct_col".withField("c", lit(3)))
Review comment:
I failed to write a test case to cover this scenario, my bad.
And yea, I just tried this example again, and I can see that it fails.
The issue is that I `override foldable` for this `Unevaluable` Expression.
And so, when `foldable` returns true, Spark tries to evaluate the expression
and it fails at that point.
I kind-of realized this as well recently and in my PR for `dropFields`
[here](https://github.com/apache/spark/pull/29322/files#diff-c1758d627a06084e577be0d33d47f44eL566),
I've fixed the issue (basically i just don't `override foldable` anymore).
I guess I should submit a follow-up PR to fix this immediately with
associated unit tests?
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