如何在SQL#中将lambda表达式作为参数传递

Question

我是初学者使用lambda表达式.

我有一个经销商名单,foreach经销商我必须计算等级.

要求是将等级计算分成单独的方法.

所以我正在编写以下两种方法,但是我无法将参数传递给CalculateGrade()方法,

public IEnumerable<Dealers> GetDealerGrades(IEnumerable<Dealers> gradeData)
{
    return gradeData
        .GroupBy(row => new { row.Name })
        .Select(g => new Dealers
        {
            Name = g.Key.Name,
            TotalPoints = CalculateGrade(x => Convert.ToDouble(x.RecievedPoints),
                                         y => y.MaxPoints,
                                         z => Convert.ToDouble(z.Weightage)) 
        })
        .ToList();
}

private double CalculateGrade(double d1, int d2, double d3)
{
    return ( d1 / d2 ) 
        * d3 == 0.00 ? 1
        : d3;
}

有人可以建议如何传递参数,或者如何传递lamda表达式并计算等级？

提前谢谢了...

Answer 1

看起来你需要:

return gradeData
    .GroupBy(row => row.Name)
    .Select(g => new Dealers
    {
        Name = g.Key.Name,
        TotalPoints = g.Sum(x => CalculateGrade(Convert.ToDouble(x.RecievedPoints),
                                                x.MaxPoints,
                                                Convert.ToDouble(x.Weightage)))
    })
    .ToList();

它将CalculateGrade从组中的每个元素上调用方法,并将返回的值汇总到TotalPoints属性中.

或者,你可以改变你CalculateGrade拿IEnumerabale<Dealers>:

private double CalculateGrade(IEnumerable<Dealers> dealers)
{
    // calculations here
    return dealers.Sum(x => CalculateGrade(Convert.ToDouble(x.RecievedPoints),
                                            x.MaxPoints,
                                            Convert.ToDouble(x.Weightage)))
}

并在您的查询中使用它:

return gradeData
    .GroupBy(row => row.Name)
    .Select(g => new Dealers
    {
        Name = g.Key.Name,
        TotalPoints = CalculateGrade(g)
    })
    .ToList();