c# – 在SQLite和Dapper中映射TimeSpan

我正在尝试使用Dapper与现有数据库格式进行交互,该数据库格式的表格的持续时间编码为BIGINT列中的刻度.在插入和读取数据库时,如何告诉Dapper将我的POCO的TimeSpan类型属性映射到滴答？

我试图将TimeSpan的类型映射设置为DbType.Int64：

SqlMapper.AddTypeMap(typeof(TimeSpan),DbType.Int64);

我还创建了一个ITypeHandler,但从未调用过SetValue方法：

public class TimeSpanToTicksHandler : SqlMapper.TypeHandler<TimeSpan>
{
    public override TimeSpan Parse(object value)
    {
        return new TimeSpan((long)value);
    }

    public override void SetValue(IDbDataParameter parameter,TimeSpan value)
    {
        parameter.Value = value.Ticks;
    }
}

这是我的POCO：

public class Task
{
    public TimeSpan Duration { get; set; }

    // etc.
}

执行这样的简单插入语句时：

string sql = "INSERT INTO Tasks (Duration) values (@Duration);";

并将POCO作为要插入的对象传递：

Task task = new Task { Duration = TimeSpan.FromSeconds(20) };
connection.Execute(sql,task);

我得到这个例外：

System.InvalidCastException : Unable to cast object of type 'System.TimeSpan' to type 'System.IConvertible'.
   at System.Convert.ToInt64(Objectvalue,IFormatProviderprovider)
   at System.Data.SQLite.SQLiteStatement.BindParameter(Int32index,SQLiteParameterparam)
   at System.Data.SQLite.SQLiteStatement.BindParameters()
   at System.Data.SQLite.SQLiteCommand.BuildNextCommand()
   at System.Data.SQLite.SQLiteCommand.GetStatement(Int32index)
   at System.Data.SQLite.SQLiteDataReader.NextResult()
   at System.Data.SQLite.SQLiteDataReader..ctor(SQLiteCommandcmd,CommandBehaviorbehave)
   at System.Data.SQLite.SQLiteCommand.ExecuteReader(CommandBehaviorbehavior)
   at System.Data.SQLite.SQLiteCommand.ExecuteNonQuery(CommandBehaviorbehavior)
   at System.Data.SQLite.SQLiteCommand.ExecuteNonQuery()
   at Dapper.SqlMapper.ExecuteCommand(IDbConnectioncnn,refCommandDefinitioncommand,Action`2paramReader) in SqlMapper.cs: line 3310
   at Dapper.SqlMapper.ExecuteImpl(IDbConnectioncnn,refCommandDefinitioncommand) in SqlMapper.cs: line 1310
   at Dapper.SqlMapper.Execute(IDbConnectioncnn,Stringsql,Objectparam,IDbTransactiontransaction,Nullable`1commandTimeout,Nullable`1commandType) in SqlMapper.cs: line 1185

如果我按原样保留TimeSpan类型映射(默认为DbType.Time),它会写入TimeSpan的字符串版本,即“00：00：20.000”,这没有用,因为它与格式不匹配列中的其他数据.

public class Task
{
    public TimeSpan Duration { get; set; }
    public long Ticks 
    { 
        get { return Duration.Ticks; }
        set { Duration = new TimeSpan(value); }
    }
    // etc.
}

string sql = "INSERT INTO Tasks (Duration) values (@Ticks);";