MySqlDataReader.GetStream() 抛出 IndexOutOfRangeException

Question

所以我正在为我的 .NET Core 项目使用 MySql.Data 包，并将密码哈希和盐（byte[] 类型）作为 varbinary() 存储到数据库中。从用户那里选择密码散列和盐时，我需要一种方法将结果转换回字节数组。给定此示例代码

Stream passwordHashStream = dbDataReader.GetStream(0);
byte[] passwordHash;
                        
using (MemoryStream memoryStream = new MemoryStream())
{
    await passwordHashStream.CopyToAsync(memoryStream);
    passwordHash = memoryStream.ToArray();
}

第一行会抛出这个异常

System.IndexOutOfRangeException: Data index must be a valid index in the field at MySql.Data.MySqlClient.Interceptors.ExceptionInterceptor.Throw(Exception exception) at MySql.Data.MySqlClient.MySqlConnection.Throw(Exception ex) at MySql.Data.MySqlClient.MySqlDataReader.Throw(Exception ex) at MySql.Data.MySqlClient.MySqlDataReader.GetBytes(Int32 i, Int64 fieldOffset, Byte[] buffer, Int32 bufferoffset, Int32 length) at System.Data.Common.DbDataReader.GetStream(Int32 ordinal) at Infrastructure.Persistence.Repositories.UsersRepository.<>c.<b__1_0>d.MoveNext() in /.../Infrastructure/Persistence/Repositories/UsersRepository.cs:line 60

尽管 reader 包含正确的数据库结果，如下所示（密码为 32 字节，哈希为 16 字节）

2018年报错

https://bugs.mysql.com/bug.php?id=93374

并且具有经过验证的状态。是否有任何好的解决方案/解决方法来解决它？我不想使用 GetBytes 方法，因为它要求我传入字节数组的长度，而我想独立于此。

Answer 1

public static async Task<MemoryStream> ToMemoryStream(this Stream stream)
    {
      var memStream = stream as MemoryStream;
      if (memStream == null)
      {
        memStream = new MemoryStream();
        await stream.CopyToAsync(memStream);
      }
      return memStream;
    }

Answer 2

卸载 MySql.Data 并将其替换为 MySqlConnector。

（披露：我是 MySql bug you found and the primary contributor to MySqlConnector 的记者。）

除了修复该问题 and many other bugs，MySqlConnector 添加了真正的异步 I/O 支持和性能改进。

I don't want to use the GetBytes method because it requires me to pass in the length of the byte array and I would like to stay independent from that.

如果您不想切换库，GetBytes（MySql.Data 和 MySqlConnector 均支持）的一个鲜为人知的功能是传入一个 null 缓冲区 returns 所需的长度，因此您无需对其进行硬编码：

// get the length of the column and allocate a buffer
var length = dbDataReader.GetBytes(0, 0, null, 0, 0);
var passwordHash = new byte[length];

// fill the buffer from the column
dbDataReader.GetBytes(0, 0, passwordHash, 0, passwordHash.Length);

MySqlDataReader.GetStream() 抛出 IndexOutOfRangeException

MySqlDataReader.GetStream() throws IndexOutOfRangeException

c#

mysql

mysql.data