可空 Guid 的 Dapper 问题？类型

Question

我对 Dapper 和 Guid? 类型有疑问。我创建了那个演示项目：

数据库MySQL (table entities):

CREATE TABLE `entities` (
  `id` int NOT NULL AUTO_INCREMENT,
  `notnullguid` char(36) NOT NULL,
  `nullguid` char(36) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

第一个 Guid 字段 - 不为空，第二个 - 可为空（默认值为 NULL）。

演示数据：

id	notnullguid	nullguid
1	7b137c4e-38db-11eb-adec-a85e45e499a0	NULL
2	f57b9036-38db-11eb-adec-a85e45e499a0	f57b906b-38db-11eb-adec-a85e45e499a0

我的实体：

public class Entity
{
    public int Id {get; set; }
    public Guid NotNullGuid { get; set; }
    public Guid? NullGuid { get; set; }
}

我的查询：

//PROBLEM:
Entity e1 = db.Query<Entity>("SELECT * FROM entities WHERE id=1").First(); //Not working

//WORKING - all variations:
Entity e2 = db.Query<Entity>("SELECT * FROM entities WHERE id=2").First(); //Working
Entity e3 = db.Query<Entity>("SELECT notnullguid FROM ents WHERE id=1;").First(); //Working
Entity e4 = db.Query<Entity>("SELECT notnullguid, NULL as nullguid FROM ents WHERE id=1;").First(); //Working
Entity e5 = db.Query<Entity>("SELECT notnullguid, IFNULL(nullguid, NULL) FROM ents WHERE id=1;").First(); //Working

如果我得到 id=1 我有那个例外：

System.Data.DataException: 'Error parsing column 2 (nullguid=7b137c4e-38db-11eb-adec-a85e45e499a0 - Object)' This exception was originally thrown at this call stack:
System.Data.DataException HResult=0x80131501 Message=Error parsing column 2 (nullguid=7b137c4e-38db-11eb-adec-a85e45e499a0 - Object)
Source=Dapper StackTrace: at Dapper.SqlMapper.ThrowDataException(Exception ex, Int32 index, IDataReader reader, Object value) in //Dapper/SqlMapper.cs:line 3665 at Dapper.SqlMapper.d__1401.MoveNext() in /_/Dapper/SqlMapper.cs:line 1102 at System.Collections.Generic.List1..ctor(IEnumerable1 collection) at System.Linq.Enumerable.ToList[TSource](IEnumerable1 source) at Dapper.SqlMapper.Query[T](IDbConnection cnn, String sql, Object param, IDbTransaction transaction, Boolean buffered, Nullable1 commandTimeout, Nullable1 commandType) in //Dapper/SqlMapper.cs:line 725 at DapperGuidParsing.Program.Main(String[] args) in C:\Users\Dmytro\source\repos\DapperGuidParsing\DapperGuidParsing\Program.cs:line 21

This exception was originally thrown at this call stack: System.ThrowHelper.ThrowArgumentOutOfRangeException(System.ExceptionArgument, System.ExceptionResource) System.Text.UTF8Encoding.GetString(byte[], int, int) MySql.Data.MySqlClient.NativeDriver.ReadColumnValue(int, MySql.Data.MySqlClient.MySqlField, MySql.Data.Types.IMySqlValue) MySql.Data.MySqlClient.ResultSet.this[int].get(int) MySql.Data.MySqlClient.MySqlDataReader.GetFieldValue(int, bool) MySql.Data.MySqlClient.MySqlDataReader.GetValue(int) MySql.Data.MySqlClient.MySqlDataReader.this[int].get(int) Inner Exception 1: ArgumentOutOfRangeException: Non-negative number required.

为什么？ :|我该如何解决这个问题？

一些技术信息：.NET Core 3.1 Console App、Dapper 2.0.78、MySql.Data 8.0.22。

Answer 1

安装 Nuget 包时一切正常 MySqlConnector

//Working
IDbConnection db = new MySqlConnector.MySqlConnection(this.ConnectionString);

//Not working (default MySqlConnection from MySql.Data package)
//IDbConnection db = new MySql.Data.MySqlClient.MySqlConnection(this.ConnectionString);

可空 Guid 的 Dapper 问题？类型

Dapper problem with a nullable Guid? types

.net

c#

dapper