Fix NpgsqlBinaryImporter when value type is changed (#3655)

Fixes #3649 (cherry picked from commit b585861)
npgsql · Apr 15, 2021 · ea77317 · ea77317
1 parent d1fd635
commit ea77317
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Showing 2 changed files with 31 additions and 1 deletion.
diff --git a/src/Npgsql/NpgsqlBinaryImporter.cs b/src/Npgsql/NpgsqlBinaryImporter.cs
@@ -317,10 +317,11 @@ async Task Write<T>([AllowNull] T value, NpgsqlParameter param, bool async, Canc
                 }
                 else
                 {
-                    if (!(param is NpgsqlParameter<T> typedParam))
+                    if (param is not NpgsqlParameter<T> typedParam)
                     {
                         _params[_column] = typedParam = new NpgsqlParameter<T>();
                         typedParam.NpgsqlDbType = param.NpgsqlDbType;
+                        param = typedParam;
                     }
                     typedParam.TypedValue = value;
                 }

diff --git a/test/Npgsql.Tests/BugTests.cs b/test/Npgsql.Tests/BugTests.cs
@@ -1351,5 +1351,34 @@ public async Task Bug3373()
             await using var reader = await cmd.ExecuteReaderAsync();
             Assert.DoesNotThrowAsync(async () => await reader.NextResultAsync());
         }
+
+        [Test, IssueLink("https://github.com/npgsql/npgsql/issues/3649")]
+        public async Task Bug3649()
+        {
+            await using var conn = await OpenConnectionAsync();
+            await using var _ = await CreateTempTable(conn, "value integer", out var table);
+
+            using (var importer = conn.BeginBinaryImport($"COPY {table} (value) FROM STDIN (FORMAT binary)"))
+            {
+                await importer.StartRowAsync();
+                await importer.WriteAsync(DBNull.Value, NpgsqlDbType.Integer);
+                await importer.StartRowAsync();
+                await importer.WriteAsync(1, NpgsqlDbType.Integer);
+                await importer.StartRowAsync();
+                await importer.WriteAsync(2, NpgsqlDbType.Integer);
+                await importer.CompleteAsync();
+            }
+
+            using (var exporter = conn.BeginBinaryExport($"COPY {table} (value) TO STDIN (FORMAT binary)"))
+            {
+                await exporter.StartRowAsync();
+                Assert.IsTrue(exporter.IsNull);
+                await exporter.SkipAsync();
+                await exporter.StartRowAsync();
+                Assert.AreEqual(1, await exporter.ReadAsync<int?>());
+                await exporter.StartRowAsync();
+                Assert.AreEqual(2, await exporter.ReadAsync<int?>());
+            }
+        }
     }
 }