From d58fe2d53c641f267e8a7dbd06a4cde8aaeb9b39 Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackchristensen.com>
Date: Wed, 19 Jul 2023 20:54:05 -0500
Subject: [PATCH] Fix json scan of non-string pointer to pointer

https://github.com/jackc/pgx/issues/1691
---
 pgtype/json.go      | 30 +++++++++++++++++-------------
 pgtype/json_test.go | 26 ++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 13 deletions(-)

diff --git a/pgtype/json.go b/pgtype/json.go
index b7a7101e..d332dd0d 100644
--- a/pgtype/json.go
+++ b/pgtype/json.go
@@ -92,6 +92,23 @@ func (JSONCodec) PlanScan(m *Map, oid uint32, format int16, target any) ScanPlan
 	switch target.(type) {
 	case *string:
 		return scanPlanAnyToString{}
+
+	case **string:
+		// This is to fix **string scanning. It seems wrong to special case **string, but it's not clear what a better
+		// solution would be.
+		//
+		// https://github.com/jackc/pgx/issues/1470 -- **string
+		// https://github.com/jackc/pgx/issues/1691 -- ** anything else
+
+		if wrapperPlan, nextDst, ok := TryPointerPointerScanPlan(target); ok {
+			if nextPlan := m.planScan(oid, format, nextDst); nextPlan != nil {
+				if _, failed := nextPlan.(*scanPlanFail); !failed {
+					wrapperPlan.SetNext(nextPlan)
+					return wrapperPlan
+				}
+			}
+		}
+
 	case *[]byte:
 		return scanPlanJSONToByteSlice{}
 	case BytesScanner:
@@ -104,19 +121,6 @@ func (JSONCodec) PlanScan(m *Map, oid uint32, format int16, target any) ScanPlan
 		return &scanPlanSQLScanner{formatCode: format}
 	}
 
-	// This is to fix **string scanning. It seems wrong to special case sql.Scanner and pointer to pointer, but it's not
-	// clear what a better solution would be.
-	//
-	// https://github.com/jackc/pgx/issues/1470
-	if wrapperPlan, nextDst, ok := TryPointerPointerScanPlan(target); ok {
-		if nextPlan := m.planScan(oid, format, nextDst); nextPlan != nil {
-			if _, failed := nextPlan.(*scanPlanFail); !failed {
-				wrapperPlan.SetNext(nextPlan)
-				return wrapperPlan
-			}
-		}
-	}
-
 	return scanPlanJSONToJSONUnmarshal{}
 }
 
diff --git a/pgtype/json_test.go b/pgtype/json_test.go
index e171104f..b4f35d06 100644
--- a/pgtype/json_test.go
+++ b/pgtype/json_test.go
@@ -121,6 +121,32 @@ func TestJSONCodecPointerToPointerToString(t *testing.T) {
 	})
 }
 
+// https://github.com/jackc/pgx/issues/1691
+func TestJSONCodecPointerToPointerToInt(t *testing.T) {
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
+		n := 44
+		p := &n
+		err := conn.QueryRow(ctx, "select 'null'::jsonb").Scan(&p)
+		require.NoError(t, err)
+		require.Nil(t, p)
+	})
+}
+
+// https://github.com/jackc/pgx/issues/1691
+func TestJSONCodecPointerToPointerToStruct(t *testing.T) {
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
+		type ImageSize struct {
+			Height int    `json:"height"`
+			Width  int    `json:"width"`
+			Str    string `json:"str"`
+		}
+		is := &ImageSize{Height: 100, Width: 100, Str: "str"}
+		err := conn.QueryRow(ctx, `select 'null'::jsonb`).Scan(&is)
+		require.NoError(t, err)
+		require.Nil(t, is)
+	})
+}
+
 func TestJSONCodecClearExistingValueBeforeUnmarshal(t *testing.T) {
 	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
 		m := map[string]any{}