From 847f888631e7356f88766bcb4986afd3c4b8fd76 Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackchristensen.com>
Date: Sat, 8 Apr 2023 14:39:48 -0500
Subject: [PATCH] Fix scan array of record to pointer to slice of struct

https://github.com/jackc/pgx/issues/1570
---
 pgtype/pgtype.go      | 15 ++++++++++-----
 pgtype/pgtype_test.go | 16 ++++++++++++++++
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/pgtype/pgtype.go b/pgtype/pgtype.go
index 83b349ce..e764bf62 100644
--- a/pgtype/pgtype.go
+++ b/pgtype/pgtype.go
@@ -1089,15 +1089,16 @@ func TryWrapPtrSliceScanPlan(target any) (plan WrappedScanPlanNextSetter, nextVa
 		return &wrapPtrSliceScanPlan[time.Time]{}, (*FlatArray[time.Time])(target), true
 	}
 
-	targetValue := reflect.ValueOf(target)
-	if targetValue.Kind() != reflect.Ptr {
+	targetType := reflect.TypeOf(target)
+	if targetType.Kind() != reflect.Ptr {
 		return nil, nil, false
 	}
 
-	targetElemValue := targetValue.Elem()
+	targetElemType := targetType.Elem()
 
-	if targetElemValue.Kind() == reflect.Slice {
-		return &wrapPtrSliceReflectScanPlan{}, &anySliceArrayReflect{slice: targetElemValue}, true
+	if targetElemType.Kind() == reflect.Slice {
+		slice := reflect.New(targetElemType).Elem()
+		return &wrapPtrSliceReflectScanPlan{}, &anySliceArrayReflect{slice: slice}, true
 	}
 	return nil, nil, false
 }
@@ -1198,6 +1199,10 @@ func (m *Map) PlanScan(oid uint32, formatCode int16, target any) ScanPlan {
 }
 
 func (m *Map) planScan(oid uint32, formatCode int16, target any) ScanPlan {
+	if target == nil {
+		return &scanPlanFail{m: m, oid: oid, formatCode: formatCode}
+	}
+
 	if _, ok := target.(*UndecodedBytes); ok {
 		return scanPlanAnyToUndecodedBytes{}
 	}
diff --git a/pgtype/pgtype_test.go b/pgtype/pgtype_test.go
index a3870d51..341ce5d8 100644
--- a/pgtype/pgtype_test.go
+++ b/pgtype/pgtype_test.go
@@ -330,6 +330,22 @@ func TestMapScanPtrToPtrToSlice(t *testing.T) {
 	require.Equal(t, []string{"foo", "bar"}, *v)
 }
 
+func TestMapScanPtrToPtrToSliceOfStruct(t *testing.T) {
+	type Team struct {
+		TeamID int
+		Name   string
+	}
+
+	// Have to use binary format because text format doesn't include type information.
+	m := pgtype.NewMap()
+	src := []byte{0x0, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x8, 0xc9, 0x0, 0x0, 0x0, 0x2, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x1e, 0x0, 0x0, 0x0, 0x2, 0x0, 0x0, 0x0, 0x17, 0x0, 0x0, 0x0, 0x4, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x19, 0x0, 0x0, 0x0, 0x6, 0x74, 0x65, 0x61, 0x6d, 0x20, 0x31, 0x0, 0x0, 0x0, 0x1e, 0x0, 0x0, 0x0, 0x2, 0x0, 0x0, 0x0, 0x17, 0x0, 0x0, 0x0, 0x4, 0x0, 0x0, 0x0, 0x2, 0x0, 0x0, 0x0, 0x19, 0x0, 0x0, 0x0, 0x6, 0x74, 0x65, 0x61, 0x6d, 0x20, 0x32}
+	var v *[]Team
+	plan := m.PlanScan(pgtype.RecordArrayOID, pgtype.BinaryFormatCode, &v)
+	err := plan.Scan(src, &v)
+	require.NoError(t, err)
+	require.Equal(t, []Team{{1, "team 1"}, {2, "team 2"}}, *v)
+}
+
 type databaseValuerString string
 
 func (s databaseValuerString) Value() (driver.Value, error) {