Linq查询中的空验证

Question

@item.qmsCallAudit.Employee.EmployeeProcesses
     .Select(e=> e.Employee1.employee_code).SingleOrDefault().ToString();

如何检查e.Employee1.employee_code的空值

Answer 1

你可以这样做：

var result = item.qmsCallAudit.Employee.EmployeeProcesses
 .Where(e => e.Employee1 != null && e.Employee1.employee_code != null)
 .Select(e=> e.Employee1.employee_code)
 .SingleOrDefault();

var code = result != null ? result.ToString() : null;

ToString()之后SingleOrDefault()不能返回null，然后会抛出异常。

Answer 2

@item.qmsCallAudit.Employee.EmployeeProcesses.Where(e => e.Employee1.employee_code != null).Select(e => e.Employee1.employee_code).SingleOrDefault().ToString();

试试这个^^