调用SQL Server存储过程时出现“指定的转换无效”错误

Question

我正在使用以下代码在SQL Server数据库中调用存储过程。

这个想法是将相关事件添加到EventSchedule模型的属性列表中，但是代码返回一个

指定的演员表无效

错误。 存储过程从我建立的视图中提取数据。 调用堆栈显示错误在第96行，不确定是否会对任何人有很大帮助。 我想我可能需要另一双眼睛才能看到我在这里缺少的东西。

var command = new SqlCommand("GetEvents", conn)
{
    CommandType = CommandType.StoredProcedure
};

command.Parameters.Add(new SqlParameter("Id", SqlDbType.BigInt, 0, "id"));
command.Parameters[0].Value = schedule.LeagueId;

using (var reader = command.ExecuteReader())
{
    while (reader.Read())
    {
        //line 96
        var _event = new Event
        {
            EventId = (Int64) reader["eventid"],
            HomeTeamId = (Int64) reader["home_team_id"],
            TeamName = (string) reader["team_name"],
            HomeTeamScore = (int) reader["home_team_score"],
            AwayTeamId = (Int64) reader["away_team_id"],
            AwayTeamName = (string) reader["Expr1"],
            AwayTeamScore = (int) reader["away_team_score"],
            WinningTeamId = (Int64) reader["winning_teamid"],
            EventStartDttm = (DateTime) reader["event_start_dttm"],
            CurrentDttm = (DateTime) reader["current_dttm"],
            Locked = (bool) reader["locked"]
        };

        schedule.Events.Add(_event);
    }
}

return schedule;

楷模：

public class EventSchedule
{
    public Int64 UserId { get; set; }
    public Int64 LeagueId { get; set; }
    public string League { get; set; }
    public int Season { get; set; }
    public int Week { get; set; }
    public IList<Event> Events { get; set; }
}

public class Event
{
    public Int64 EventId { get; set; }
    public Int64 HomeTeamId { get; set; }
    public string TeamName { get; set; }
    public int? HomeTeamScore { get; set; }
    public Int64 AwayTeamId { get; set; }
    public string AwayTeamName { get; set; }
    public int? AwayTeamScore { get; set; }
    public Int64 WinningTeamId { get; set; }
    public DateTime EventStartDttm { get; set; }
    public DateTime CurrentDttm { get; set; }
    public bool Locked { get; set; }
}

存储过程：

ALTER PROCEDURE [dbo].[GetEvents]
    @Id int
AS
BEGIN
    SET NOCOUNT ON;

    SELECT 
       eventid, 
       home_team_id, 
       team_name, 
       home_team_score, 
       away_team_id, 
       Expr1, 
       away_team_score, 
       winning_teamid, 
       event_start_dttm, 
       current_dttm, 
       locked 
    FROM 
       leagueScheduleForCurrentWeek 
    WHERE 
       id = @Id
END

Answer 1

您的问题来自以下事实：您的一种强制转换失败，很可能是模型中的可空类型之一。 从铸造到使用更改as为空类型，这将导致DbNull.Value （这是正在被读者返回）要来你想要的空值。

    var _event = new Event
    {
        EventId = (Int64) reader["eventid"],
        HomeTeamId = (Int64) reader["home_team_id"],
        TeamName = (string) reader["team_name"],
        HomeTeamScore = reader["home_team_score"] as int?, //here
        AwayTeamId = (Int64) reader["away_team_id"],
        AwayTeamName = (string) reader["Expr1"],
        AwayTeamScore = reader["away_team_score"] as int?, //and here
        WinningTeamId = (Int64) reader["winning_teamid"],
        EventStartDttm = (DateTime) reader["event_start_dttm"],
        CurrentDttm = (DateTime) reader["current_dttm"],
        Locked = (bool) reader["locked"]
    };

如果问题仍然存在，则您的模型与数据表不匹配。 您将需要仔细检查您的类型，以找出不匹配的类型。 您可以通过从构造函数中分配分配来简化此工作。

    var _event = new Event();

    _event.EventId = (Int64) reader["eventid"];
    _event.HomeTeamId = (Int64) reader["home_team_id"];
    _event.TeamName = (string) reader["team_name"];
    _event.HomeTeamScore = reader["home_team_score"] as int?;
    _event.AwayTeamId = (Int64) reader["away_team_id"];
    _event.AwayTeamName = (string) reader["Expr1"];
    _event.AwayTeamScore = reader["away_team_score"] as int?;
    _event.WinningTeamId = (Int64) reader["winning_teamid"];
    _event.EventStartDttm = (DateTime) reader["event_start_dttm"];
    _event.CurrentDttm = (DateTime) reader["current_dttm"];
    _event.Locked = (bool) reader["locked"];