实体框架未加载相关对象 [英] Entity Framework not loading related objects

问题描述

我是Entity Framework的新手，但是可能会误解某些事情，或者做错了什么事情。

I am new to Entity Framework, but might be misunderstanding something, or doing something wrong.

我的代码，是给我一个特定人员的任务列表：

My code, to get me a list of tasks for a particular person :

 public List<TaskObject> GetAssignedTasks(int personId)
        {
            var items = (from s in _te.tasks where s.person.person_id == personId select s).ToList();
            var tasks = new List<TaskObject>();
            foreach (var t in items)
            {

                TaskObject tk = Transformer.UnpackTask(t);

                tasks.Add(tk);
            }
            return tasks;
        }

我的问题是，似乎返回了记录列表，但相关项目未加载。我的 Transformer.UnpackTask方法采用我加载的任务实体，然后将其转换为通过业务/服务层到达UI的其他对象。

My problem is, it seems to get a list of records back, but related items are not loaded. My 'Transformer.UnpackTask' method takes the task entity which I loaded, and then transforms it into a different object which goes up to the UI via the business/service layers.

但是，一旦我的Unpacker函数尝试引用作为相关对象的项目（例如，任务具有一个 AssignedPerson，该对象具有一个包含人员详细信息的Person实体。但是我的实体的AssignedPerson属性为NULL。

But as soon as my Unpacker function tries to references an item which is a related object (For example, a task has an 'AssignedPerson', which has a Person entity with person details. But the AssignedPerson property of my entity is NULL. I thought it would load the related items.

我误会了吗？

推荐答案

您应该使用Include（）方法显式地包含引用。
它有两个重载：一个将属性作为lambda表达式，另一个将路径作为字符串加载（在需要加载引用时有用）集合中可用的对象）。

You should explicitly include references with the Include() method. It has two overloads: one takes the property as lambda expression, the other takes the path to load as a string (useful when you need to load references on objects available in collections).

MSDN参考

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