From 930ca694c5017eb410987510710246e49b84244e Mon Sep 17 00:00:00 2001
From: Anderson Silva <joyle@outlook.com>
Date: Mon, 19 Aug 2024 19:03:32 -0500
Subject: [PATCH] ColumnName to work with array untyped object (#2601)

Reply to https://github.com/microsoft/Power-Fx/pull/2588.
---
 .../Functions/LibraryUntypedObject.cs         |  2 +-
 .../PadUntypedObjectTests.cs                  | 31 ++++++++++++++++++-
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/src/libraries/Microsoft.PowerFx.Interpreter/Functions/LibraryUntypedObject.cs b/src/libraries/Microsoft.PowerFx.Interpreter/Functions/LibraryUntypedObject.cs
index 28dc9a4e20..771d35ef8a 100644
--- a/src/libraries/Microsoft.PowerFx.Interpreter/Functions/LibraryUntypedObject.cs
+++ b/src/libraries/Microsoft.PowerFx.Interpreter/Functions/LibraryUntypedObject.cs
@@ -437,7 +437,7 @@ public static FormulaValue ColumnNames_UO(IRContext irContext, UntypedObjectValu
         {
             var impl = args[0].Impl;
 
-            if (impl.Type is ExternalType externalType && externalType.Kind == ExternalTypeKind.Object)
+            if (impl.Type is ExternalType externalType && (externalType.Kind == ExternalTypeKind.Object || externalType.Kind == ExternalTypeKind.ArrayAndObject))
             {
                 if (impl.TryGetPropertyNames(out var propertyNames))
                 {
diff --git a/src/tests/Microsoft.PowerFx.Interpreter.Tests.Shared/PadUntypedObjectTests.cs b/src/tests/Microsoft.PowerFx.Interpreter.Tests.Shared/PadUntypedObjectTests.cs
index 12ca12e450..353873c5a1 100644
--- a/src/tests/Microsoft.PowerFx.Interpreter.Tests.Shared/PadUntypedObjectTests.cs
+++ b/src/tests/Microsoft.PowerFx.Interpreter.Tests.Shared/PadUntypedObjectTests.cs
@@ -161,6 +161,23 @@ public void PadUntypedObjectMissingProperty()
             // PadUntypedObject2 overrides GetProperty. Returns error if property is missing.
             var result2 = engine.Eval(@"Index(padTable2, 1).Missing");
             Assert.IsType<ErrorValue>(result2);
+        }
+
+        [Fact]
+        public void PadUntypedObject2ColumnNamesTest()
+        {
+            var uo = new PadUntypedObject2(GetDataTable());
+            var uov = new UntypedObjectValue(IRContext.NotInSource(FormulaType.UntypedObject), uo);
+
+            PowerFxConfig config = new PowerFxConfig(Features.PowerFxV1);
+            RecalcEngine engine = new RecalcEngine(config);
+
+            engine.Config.SymbolTable.EnableMutationFunctions();
+            engine.UpdateVariable("padTable", uov, new SymbolProperties() { CanMutate = true, CanSetMutate = true });
+
+            var result = engine.Eval(@"ColumnNames(Index(padTable, 1))");
+
+            Assert.IsAssignableFrom<TableValue>(result);
         }
 
         private DataTable GetDataTable()
@@ -570,7 +587,19 @@ public override bool TryGetProperty(string propertyName, out IUntypedObject resu
         }
 
         public override bool TryGetPropertyNames(out IEnumerable<string> result)
-        {
+        {
+            if (DataTable != null)
+            {
+                result = DataTable.Columns.Cast<DataColumn>().Select(c => c.ColumnName);
+                return true;
+            }
+
+            if (DataRow != null)
+            {
+                result = DataRow.Table.Columns.Cast<DataColumn>().Select(c => c.ColumnName);
+                return true;
+            }
+
             result = null;
             return false;
         }