c#，LINQ to Entities 无法识别方法'Int32 [重复]

Question

当我尝试通过生日属性在 dataGridView 中显示年龄时出现以下错误

LINQ to Entities 无法识别方法 'Int32 CalculateAge(System.Datetime) 方法，并且该方法无法转换为存储表达式

这是我用来计算年龄的函数：

        private int CalculateAge(string birthday)
        {
            int age;
            if (string.IsNullOrWhiteSpace(birthday)) return 0;

            DateTime empBirthday = Convert.ToDateTime(birthday);
            DateTime today = DateTime.Today;
            age = today.Year - empBirthday.Year;
            if (empBirthday > today.AddYears(-age))
                age--;
            return age;
        }

这是显示在 datagradView 上

var employee = db.Employee.Where(x => x.EmployeeId == id ).
               Select(b => new
               {
                  Id = b.EmployeeId, 
                  Namn = b.FirstName + " " + b..LastName,
                  Age = CalculateAge(b.DOB.ToString()),
                  Department = b.Department.DepartmentName
                  } ).Tolist();
if employee != null)
{
   dgvEmployee.DataSource = null;
   dgvEmployee.DataSource = employee 

}

但它不适用于 CalculateAge 函数。我该怎么做才能解决这个问题？请帮助，并在此先感谢您： 错误信息是 "LINQ to Entities 无法识别方法 'Int32 CalculateAge(System.Datetime) 方法，并且该方法无法转换为存储表达式"

Answer 1

尝试查询您需要的数据，然后将集合转换为IEnumerable<T>，然后使用CalculateAge() 方法。

var employee = db.Employee.Where(x => x.EmployeeId == id ).
               Select(e => new { e.EmployeeId, e.FirstName, e.LastName, e.DOB, e.Department.DepartmentName }).
               AsEnumerable().
               Select(b => new
               {
                  Id = b.EmployeeId, 
                  Name = b.FirstName + " " + b.LastName,
                  Age = CalculateAge(b.DOB.ToString()),
                  Department = b.DepartmentName
                  } ).Tolist();
if employee != null)
{
   dgvEmployee.DataSource = employee;
}