Question

我的项目中有一个Employee，customer和customerSelectedCover类。员工类与客户类具有一对多关系，客户类与customerSelectedCover具有一对多关系。我还在项目中为Employee创建了一个存储库。在我的项目中，我通过以下代码获得当前员工

var current = employeeRepository
    .FindBy(c => c.UserName == User.Identity.Name)
    .Single();

在linq查询中，当前员工obj从db检索所有customerSelectedCover的最佳方法是什么？

Answer 1

使用Include方法获取Customers集合，然后使用SelectMany方法在给定员工的所有客户中投影所有CustomerSelectedCovers，请考虑以下示例代码，模拟您的需求。（最小的属性用于演示目的）

class Program
    {
        static void Main(string[] args)
        {
            Employee CurrentEmployee = new Employee();
            List<CustomerSelectedCover> Covers = CurrentEmployee.Customers.
                                                                Include("CustomerSelectedCovers").
                                                                SelectMany(o => o.CustomerSelectedCovers).ToList();


        }
    }
    class Employee
    {
        public int Id;
        public DbSet<Customer> Customers;
    }

    class Customer
    {
        public int Id;
        public int EmployeeId;
        public DbSet<CustomerSelectedCover> CustomerSelectedCovers;

    }
    class CustomerSelectedCover
    {
        public int Id;
        public int CustomerId;
    }

详细了解Include here 和SelectMany here

Linq通过Entity框架查询子类

1 个答案: