c# - 如何从 IQueryable 获取计数

Question

我正在我的 GridView 中实现分页。来自 this文章，我需要两种方法:

public IQueryable BindEmployees(int startRowIndex, int maximumRows)
{
    EmployeeInfoDataContext dbEmp = new EmployeeInfoDataContext();
    var query = from emp in dbEmp.Employees
                join dept in dbEmp.Departments
                    on emp.DeptID equals dept.DeptID
                select new
                {
                    EmpID = emp.EmpID,
                    EmpName = emp.EmpName,
                    Age = emp.Age,
                    Address = emp.Address,
                    DeptName = dept.DepartmentName
                };

    return query.Skip(startRowIndex).Take(maximumRows);
} 

和

public int GetEmployeeCount()
{
    // How can I not repeat the logic above to get the count?
}

如何从第一个方法 BindEmployees 中获取第二个方法 GetEmployeeCount 的值？我的意思是不重复逻辑(查询)？

Answer 1

一个选项是:

public IQueryable BindEmployees(int startRowIndex, int maximumRows, out int count)
{
    EmployeeInfoDataContext dbEmp = new EmployeeInfoDataContext();
    var query = from emp in dbEmp.Employees
                join dept in dbEmp.Departments
                    on emp.DeptID equals dept.DeptID
                select new
                {
                    EmpID = emp.EmpID,
                    EmpName = emp.EmpName,
                    Age = emp.Age,
                    Address = emp.Address,
                    DeptName = dept.DepartmentName
                };

    count = query.Count();
    return query.Skip(startRowIndex).Take(maximumRows);
}

另一种选择是将查询传递给分页函数。