Exception in MySqlConnector.Protocol.Serialization.ByteBufferWriter.Write

[mzji]

Exception message:

[2018-06-16 17:32:31 084] System.ArgumentException: The output byte buffer is too small to contain the encoded data, encoding 'Unicode (UTF-8)' fallback 'System.Text.EncoderReplacementFallback'.
Parameter name: bytes
   at System.Text.Encoding.ThrowBytesOverflow()
   at System.Text.Encoding.ThrowBytesOverflow(EncoderNLS encoder, Boolean nothingEncoded)
   at System.Text.UTF8Encoding.GetBytes(Char* chars, Int32 charCount, Byte* bytes, Int32 byteCount, EncoderNLS baseEncoder)
   at System.Text.EncoderNLS.Convert(Char* chars, Int32 charCount, Byte* bytes, Int32 byteCount, Boolean flush, Int32& charsUsed, Int32& bytesUsed, Boolean& completed)
   at MySqlConnector.Protocol.Serialization.ByteBufferWriter.Write(ReadOnlySpan`1 chars) in C:\projects\mysqlconnector\src\MySqlConnector\Protocol\Serialization\ByteBufferWriter.cs:line 147
   at MySql.Data.MySqlClient.MySqlParameter.AppendSqlString(ByteBufferWriter writer, StatementPreparerOptions options, String parameterName) in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlParameter.cs:line 191
   at MySqlConnector.Core.StatementPreparer.ParameterSqlParser.DoAppendParameter(Int32 parameterIndex, Int32 textIndex, Int32 textLength) in C:\projects\mysqlconnector\src\MySqlConnector\Core\StatementPreparer.cs:line 68
   at MySqlConnector.Core.SqlParser.Parse(String sql) in C:\projects\mysqlconnector\src\MySqlConnector\Core\SqlParser.cs:line 112
   at MySqlConnector.Core.StatementPreparer.ParseAndBindParameters() in C:\projects\mysqlconnector\src\MySqlConnector\Core\StatementPreparer.cs:line 27
   at MySqlConnector.Core.TextCommandExecutor.CreateQueryPayload(String commandText, MySqlParameterCollection parameterCollection) in C:\projects\mysqlconnector\src\MySqlConnector\Core\TextCommandExecutor.cs:line 121
   at MySqlConnector.Core.TextCommandExecutor.<ExecuteReaderAsync>d__3.MoveNext() in C:\projects\mysqlconnector\src\MySqlConnector\Core\TextCommandExecutor.cs:line 65
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MySqlConnector.Core.TextCommandExecutor.<ExecuteScalarAsync>d__2.MoveNext() in C:\projects\mysqlconnector\src\MySqlConnector\Core\TextCommandExecutor.cs:line 43
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteScalar() in C:\projects\mysqlconnector\src\MySqlConnector\MySql.Data.MySqlClient\MySqlCommand.cs:line 66
   at SXLibraryCore.DbConnectionHelper.<>c.<GetObject>b__15_0(DbCommand cmd) in C:\Users\XXXX\Desktop\AreaPlatform\SXLibraryCore\SXLibraryCore\DBHelper.cs:line 465
   at SXLibraryCore.DbConnectionHelper.Common[T](DbConnection conn, String sqlStr, CommandType cmdType, IDictionary`2 arguments, Func`2 inner) in C:\Users\XXXX\Desktop\AreaPlatform\SXLibraryCore\SXLibraryCore\DBHelper.cs:line 264
   at SXLibraryCore.DbConnectionHelper.GetObject(DbConnection conn, String sqlStr, CommandType cmdType, Dictionary`2 arguments) in C:\Users\XXXX\Desktop\AreaPlatform\SXLibraryCore\SXLibraryCore\DBHelper.cs:line 465
   at SXLibraryCore.DbConnectionHelper.GetString(DbConnection conn, String sqlStr, CommandType cmdType, Dictionary`2 arguments) in C:\Users\XXXX\Desktop\AreaPlatform\SXLibraryCore\SXLibraryCore\DBHelper.cs:line 432
   at SXLibraryCore.DbConnectionHelper.GetString(DbConnection conn, String sqlStr, Dictionary`2 arguments) in C:\Users\XXXX\Desktop\AreaPlatform\SXLibraryCore\SXLibraryCore\DBHelper.cs:line 425
   at PTAdmin.SX.MP.GetTemplateId(String shortId, String name) in C:\Users\XXXX\Desktop\AreaPlatform\PTAdmin\PTAdmin\SX.cs:line 44
   at PTAdmin.Controllers.LoginController.LoginToken(String phoneNumber) in C:\Users\XXXX\Desktop\AreaPlatform\PTAdmin\PTAdmin\Controllers\LoginController.cs:line 133

The SQL statement, parameters and query results contain some Chinese characters, could that be the root of this issue?
.NET Core runtime: v2.0.5
MysqlConnector: 0.42.0

[mzji]

Seems like we could fallback to use the old code path to prevent using ReadOnlySpan<T> in .Net Stanard 2.0 .

[bgrainger]

Can you provide the SQL statement and parameters that cause this exception?

[bgrainger]

The docs say this exception is thrown when:

The output buffer is too small to contain any of the converted input.

This means we need to change the check here to reallocate if the buffer is potentially too small to contain one character (i.e., 4 UTF-8 bytes):

MySqlConnector/src/MySqlConnector/Protocol/Serialization/ByteBufferWriter.cs

Line 151 in 8e1e56a

if (m_output.Length == 0)

This will be fixed soon.

[bgrainger]

Fixed in 0.42.1.

[mzji]

Confirmed, it's working now.