c# – Linq的三元操作符

发布时间：2020-12-16 00:25:24 所属栏目：百科来源：网络整理

导读：var result = from payroll in currentMonthPayroll select new SalaryDifference { PreviousMonthSalary = previousMonthPayroll.Where(t = t.EmployeeId == payroll.EmployeeId).FirstOrDefault() == null ? default(decimal) : previousMonthPayroll.Wher

var result = from payroll in currentMonthPayroll
                         select new SalaryDifference
                         {
                             PreviousMonthSalary = previousMonthPayroll.Where(t => t.EmployeeId == payroll.EmployeeId).FirstOrDefault() == null ?
                              default(decimal) : previousMonthPayroll.Where(t => t.EmployeeId == payroll.EmployeeId).FirstOrDefault().Salary,};

有没有办法不重复previousMonthPayroll.Where(t => t.EmployeeId == payroll.EmployeeId).FirstOrDefault()逻辑来选择薪资值？

我试过了：

previousMonthPayroll.Where(t => t.EmployeeId == payroll.EmployeeId)
                    .FirstOrDefault().Salary ?? default(decimal);

但是,如果previousMonthPayroll.Where(t => t.EmployeeId == payroll.EmployeeId).FirstOrDefault()为null,则抛出异常.

解决方法

正如所有答案所见,有几种方法可以做到这一点,我的首选方式是：

var result = from payroll in currentMonthPayroll
             select new SalaryDifference
             {
                 PreviousMonthSalary = previousMonthPayroll
                     .Where(t => t.EmployeeId == payroll.EmployeeId)
                     .Select(prev => prev.Salary)
                     .FirstOrDefault()
             };

（编辑：李大同）

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