RowToStructByName Snake Case Collision

rows.go

@@ -797,7 +797,7 @@ func computeNamedStructFields(
 			if !dbTagPresent {
 				colName = sf.Name
 			}
-			fpos := fieldPosByName(fldDescs, colName)
+			fpos := fieldPosByName(fldDescs, colName, !dbTagPresent)
 			if fpos == -1 {
 				if missingField == "" {
 					missingField = colName
@@ -816,16 +816,21 @@ func computeNamedStructFields(
 
 const structTagKey = "db"
 
-func fieldPosByName(fldDescs []pgconn.FieldDescription, field string) (i int) {
+func fieldPosByName(fldDescs []pgconn.FieldDescription, field string, normalize bool) (i int) {
 	i = -1
-	for i, desc := range fldDescs {
 
-		// Snake case support.
+	if normalize {
 		field = strings.ReplaceAll(field, "_", "")
-		descName := strings.ReplaceAll(desc.Name, "_", "")
-
-		if strings.EqualFold(descName, field) {
-			return i
+	}
+	for i, desc := range fldDescs {
+		if normalize {
+			if strings.EqualFold(strings.ReplaceAll(desc.Name, "_", ""), field) {
+				return i
+			}
+		} else {
+			if desc.Name == field {
+				return i
+			}
 		}
 	}
 	return

rows_test.go

@@ -667,6 +667,41 @@ func TestRowToStructByName(t *testing.T) {
 	})
 }
 
+func TestRowToStructByNameDbTags(t *testing.T) {
+	type person struct {
+		Last             string `db:"last_name"`
+		First            string `db:"first_name"`
+		Age              int32  `db:"age"`
+		AccountID        string `db:"account_id"`
+		AnotherAccountID string `db:"account__id"`
+	}
+
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
+		rows, _ := conn.Query(ctx, `select 'John' as first_name, 'Smith' as last_name, n as age, 'd5e49d3f' as account_id, '5e49d321' as account__id from generate_series(0, 9) n`)
+		slice, err := pgx.CollectRows(rows, pgx.RowToStructByName[person])
+		assert.NoError(t, err)
+
+		assert.Len(t, slice, 10)
+		for i := range slice {
+			assert.Equal(t, "Smith", slice[i].Last)
+			assert.Equal(t, "John", slice[i].First)
+			assert.EqualValues(t, i, slice[i].Age)
+			assert.Equal(t, "d5e49d3f", slice[i].AccountID)
+			assert.Equal(t, "5e49d321", slice[i].AnotherAccountID)
+		}
+
+		// check missing fields in a returned row
+		rows, _ = conn.Query(ctx, `select 'Smith' as last_name, n as age from generate_series(0, 9) n`)
+		_, err = pgx.CollectRows(rows, pgx.RowToStructByName[person])
+		assert.ErrorContains(t, err, "cannot find field first_name in returned row")
+
+		// check missing field in a destination struct
+		rows, _ = conn.Query(ctx, `select 'John' as first_name, 'Smith' as last_name, n as age, 'd5e49d3f' as account_id, '5e49d321' as account__id, null as ignore from generate_series(0, 9) n`)
+		_, err = pgx.CollectRows(rows, pgx.RowToAddrOfStructByName[person])
+		assert.ErrorContains(t, err, "struct doesn't have corresponding row field ignore")
+	})
+}
+
 func TestRowToStructByNameEmbeddedStruct(t *testing.T) {
 	type Name struct {
 		Last  string `db:"last_name"`