如何在 LINQ 查询中执行代码

Question

我的查询如下所示：

    var results = from person
                  where <here I need to do something like if person is of type 
Employee, call person.GetSalary() > 100000 but if the person is of type Contractor, I need to execute 
several lines of code before doing a person.GetSalary() > 100000 
                  select new {person.Name}

难点在于构造 where 子句。有人可以帮我完成这个查询吗？

Answer 1

您始终可以编写一个执行逻辑检查的方法，并在单独的 where 子句中调用它。要使用 LINQ-to-Entities 执行此操作，您必须首先使用 AsEnumerable() 实现结果：

bool CheckEmployeeOrContractorSalary( Person p, decimal salaryLevel )
{
   // put your employee and contractor logic here...
   if( p is Employee ) {
       return p.GetSalary() > salaryLevel; }
   else if( p is Contractor ) {
       // ... your complex logic...
       return p.GetSalary() > salaryLevel; }
   else
       // ??? 
       return false;
}

现在你可以写了：

var results = from person in (
                  (from p in person select new { p.Name } ).AsEnumerable())
              where CheckEmployeeOrContractorSalary( person, 100000 )
              select new {person.Name};