Question

我尝试调用存储在数据库中的标量函数。这是我的代码：

public class PronosticDbContext : DbContext
{
    public PronosticDbContext(DbContextOptions<PronosticDbContext> options) : base(options)
    {

    }

    [DbFunction(FunctionName = "GetPlayerPointsForDay", Schema = "dbo")]
    public static int GetPlayerPointsForDay(int dayId, int userId) => throw new NotSupportedException();    
}

通话：

private IQueryable<PlayerRankingData> GetPlayerRanking(int? dayId)
{
    return Context.Days.Where(x => x.Id == dayId.Value).Select(x => new PlayerRankingData
    {
        // Some properties
        Users = x.Season.Users.Select(us => new PlayerRankingData.User
        {
            // Other properties
            Last = PronosticDbContext.GetPlayerPointsForDay(x.Id, us.User.Id),
            // Others again
        }).OrderByDescending(u => u.Points).ThenByDescending(u => u.Last).ThenBy(u => u.Login)
    });
}

我不明白为什么，但是我总是去NotSupportedException，我的标量函数从未被调用过。我为什么想念？

我也尝试过这样，但结果相同...

modelBuilder
    .HasDbFunction(typeof(PronosticDbContext).GetMethod(nameof(GetPlayerPointsForDay)))
    .HasSchema("dbo")
    .HasName(nameof(GetPlayerPointsForDay));

Answer 1

好吧，我明白了。

问题是您不能直接调用标量函数（我不知道为什么），它必须封装在linq查询中，如下所示：

Last = Context.Users.Select(u => PronosticDbContext.GetPlayerPointsForDay(x.Id, us.User.Id)).FirstOrDefault()

仅此而已。无需在DbContext中声明，就足够了：

[DbFunction]
public static int? GetPlayerPointsForDay(int dayId, int userId) => throw new NotSupportedException();

使用EF core 2.1调用DbFunction

1 个答案: