从继承的类加载导航属性 [英] Load navigation property from inherited class

问题描述

我想获取所有联系人实体（包括人->员工）

I want to get all contact entities (including Person -> Employees)

Contact
|<- Person
|   |-> Employer
|
|<- Organization 
|   |-> Employees

人员和组织从Contact继承。

Person and Organization inherits from Contact.

当我使用FirstOrDefault时，未加载我的员工和雇主实体。

When i use FirstOrDefault my employees and my employer entity were not loaded.

public Contact GetContactById(int id)
{
    var contact = GetContacts().FirstOrDefault(c => c.Id == id);
    return contact;
}

private IQueryable<Contact> GetContacts()
{
    var contacts = _contextProvider.Context.Contacts
        .Include("Addresses");

    return contacts;
}

这是我目前的解决方法：

That's my current workaround:

public Contact GetContactById(int id)
{
    var contact = GetContacts().FirstOrDefault(c => c.Id == id);
    if (contact is Organization)
    {
        var organization = contact as Organization;
        _contextProvider.Context.Entry(organization).Collection(o => o.Employees).Load();
    }
    else if (contact is Person)
    {
        var person = contact as Person;
        _contextProvider.Context.Entry(person).Reference(o => o.Employer).Load();
    }
    return contact;
}

是否有更好的方法来解决此问题？

Is there a better way to solve this problem?

推荐答案

我无法对此进行测试，但可能会向正确的方向轻推

I can't test this but a possible nudge in the right direction could be

private IQueryable<Contact> GetContacts()
{
    var people = _contextProvider.Context.Contacts
        .OfType<Person>()
        .Include("Employer");

    var organizations = _contextProvider.Context.Contacts
        .OfType<Organization>()
        .Include("Employees");

    return people.Concat<Contact>(organizations);
}

这篇关于从继承的类加载导航属性的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！