c# - 实体框架：访问关联

Question

我的具有关联的域模型如下：

• Project有很多Tasks
• Task有很多Users

根据 a 的状态User，我需要更新项目中的一个字段。我的查询如下：

var projects = from project in _data.projects
               join task in _data.tasks on project.ProjectID equals task.ProjectID
               join user in _data.usersactive on task.TaskID equals user.TaskID
               where user.Active == false
               select project;

这使我可以获取具有非活动用户的项目。

foreach (Project project in projects)
{
    bool needUpdate = false;

    foreach (Task task in project.tasks)
    {
        foreach (User user in task.users)
        {
            // Depending on state of user
            // needUpdate = true;
        }
    }

    // If needUpdate = true
    // Do something
}

显然，这段代码会让我：

There is already an open DataReader associated with this Connection which must be closed first.

但是，我在 MySQL 上，因此无法简单地利用MultipleActiveResultSets=True.

我如何能够急切地加载这些关联并让它们在foreach循环中访问？

Answer 1

急切地加载一个 linq 集：

var projects = (from project in _data.projects
               join task in 
                       _data.tasks on project.ProjectID equals task.ProjectID
               join user in 
                       _data.usersactive on task.TaskID equals user.TaskID
               where user.Active == false
               select project).ToList();