EF Linq-如何在同一查询中选择子级？

Question

I have Oracle db with EF 5 on top of it.

Lets say I have tables Company and Orders. I have EF corresponding entities where Company has field

List<Orders> Orders .

I dont want to create an association .

I have a query which is IQuerable and I need to fill the Orders for each company using

order.CompanyId == company.Id

I cant wrap my head around this atm.. Any help will be appreciated.

EDIT: not every company has orders. The orders list could be empty.

Answer 1

I would consider using the .Join() method to include the Orders table. I write this from memory, so please forgive syntax errors.

//I only use this bc I don't know the full schema.
class DTOCompany {
  public int ID {get;set;}
  public List<Orders> Orders {get;set;}
}

public List<Companies> GetCompaniesOrders() {

  using (var db = new Entities()) {
    return db.Companies
      .AsEnumerable() //may not be needed.
      .Join(db.Orders,
        c => CompanyId,
        o => o.CompanyId,
        (c,o) => new { Company = c, Orders = o})
      )
      .Select(co => new DTOCompany() {
        ID = co.Companies.CompanyId,
        Orders = co.Orders.ToList()
      })
      .ToList();
  }
}