ganeshashree commented on code in PR #58450:
URL: https://github.com/apache/spark/pull/58450#discussion_r3930734559
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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/jsonExpressions.scala:
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@@ -1651,6 +1651,129 @@ object JsonArray {
}
}
+// Built-in forms for the plain SQL/JSON constructor and path-function calls
that `AstBuilder`
+// routes through function resolution. Each rebuilds its expression with the
standard clause
+// defaults when unshadowed.
+
+@ExpressionDescription(
+ usage = "_FUNC_([expr[, ...]]) - Returns a JSON array string with NULL
elements dropped.",
+ arguments = """
+ Arguments:
+ * expr - the elements to place in the array.
+ """,
+ examples = """
+ Examples:
+ > SELECT _FUNC_(1, 'x', true);
+ [1,"x",true]
+ > SELECT _FUNC_(1, NULL, 3);
+ [1,3]
+ > SELECT _FUNC_();
+ []
+ """,
+ since = "4.4.0",
+ group = "json_funcs")
+object JsonArrayExpressionBuilder extends ExpressionBuilder {
+ override def build(funcName: String, expressions: Seq[Expression]):
Expression = {
+ // A routed call carries no lexical FORMAT JSON, so every element is a
plain value (quoted).
+ // Splicing a nested constructor is only reachable via `JSON_ARRAY(...)`
syntax (which freezes
+ // the decision lexically); doing so through a routed call is left as a
follow-up.
+ val flags = expressions.map(_ => false)
+ JsonArray(expressions, flags, flags, JsonConstructorNullBehavior.Absent,
StringType)
+ }
+}
+
+/**
+ * Shared builder for the plain `JSON_VALUE` / `JSON_QUERY` / `JSON_EXISTS`
forms. The path must
+ * be a foldable string expression; the parser-only SQL/JSON syntax supplies a
string literal,
+ * while ordinary function-call syntax can reach this builder with any
constant string expression.
+ */
+abstract class JsonPathExpressionBuilder extends ExpressionBuilder {
+ protected def buildWithPath(jsonExpr: Expression, path: String): Expression
+
+ override final def build(funcName: String, expressions: Seq[Expression]):
Expression = {
+ if (expressions.length != 2) {
+ throw QueryCompilationErrors.wrongNumArgsError(funcName, Seq(2),
expressions.length)
+ }
+ val pathExpr = expressions(1)
+ pathExpr.dataType match {
+ case _: StringType if pathExpr.foldable =>
+ val pathValue = pathExpr.eval()
Review Comment:
Agreed. It mirrors `Extract.createExpr` and only affects
foldable-but-throwing path expressions, so leaving it for now. Captured in the
"Follow-ups" section.
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