[GitHub] [spark] cloud-fan commented on a diff in pull request #38865: [SPARK-41232][SQL][PYTHON] Adding array_append function

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

cloud-fan commented on code in PR #38865:
URL: https://github.com/apache/spark/pull/38865#discussion_r1057508495


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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala:
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@@ -4600,3 +4600,69 @@ case class ArrayExcept(left: Expression, right: Expression) extends ArrayBinaryL
   override protected def withNewChildrenInternal(
     newLeft: Expression, newRight: Expression): ArrayExcept = copy(left = newLeft, right = newRight)
 }
+
+/**
+ * Given an array, and another element append the element at the end of the array.
+ */
+@ExpressionDescription(
+  usage = "_FUNC_(expr, expr) - Prepend the element",
+  examples = """
+    Examples:
+      > SELECT _FUNC_(array('b', 'd', 'c', 'a'), array(1, 2, 3, 4));
+
+  """,
+  since = "3.4.0",
+  group = "collection_funcs")
+case class ArrayAppend(left: Expression, right: Expression)
+    extends BinaryExpression
+    with ImplicitCastInputTypes {
+  override def prettyName: String = "array_append"
+  override def inputTypes: Seq[AbstractDataType] = Seq(ArrayType, AnyDataType)
+
+  override def checkInputDataTypes(): TypeCheckResult = {
+    (left.dataType, right.dataType) match {
+      case (ArrayType(e1, _), (e2)) if e1.sameType(e2) =>
+        TypeCheckResult.TypeCheckSuccess
+      case _ =>

Review Comment:
   We have no other choice. Spark array type only allows one element type. We can find the wider type the array element type and the data type of the to-be-added value.



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