获取资源 - 活动对列表。实体框架

Question

1. 以下是我在项目中使用的 DbContext 和模型的要点 - DbContextModels。
2. 以下是这些关系：
   • User - Role M ： M
   • Role - Activity - Resource M ：中号：中号
3. 联接表明确定义为 RoleResourceActivity
4. 考虑种子方法 - DbContextSeed

以下是我使用Linq尝试实现的基本 sql - 查询：

select
    r.Name [resource], a.Name
from Activities a
    join RoleResourceActivities ra on ra.ActivityId = a.Id
    join Resources r on ra.ResourceId = r.Id
    join Roles ro on ra.RoleId = ro.Id
    join UserRoles ur on ur.Role_Id = ro.Id
    join Users u on ur.User_Id = u.Id
where u.Username = 'User'
group by r.Name, a.Name

用户和 User2 的结果相应：



问题

如何编写这样的linq-query，以便结果集包含投影对象，如：

new {
    Resource = Resource.Name,
    Activities = ListOfCorrespondingActivities
}

或 JSON ：

// Username: `User`, Roles: "SimpleUser", "AdvancedUser"
[
     {Resource: "blogs", Activities: ["Delete", "Read", "Update"]},
     {Resource: "talks", Activities: ["Delete", "Read", "Update"]}
]

// Username: `User2`, Roles: "SimpleUser"
[
     {Resource: "blogs", Activities: ["Read"]},
     {Resource: "talks", Activities: ["Read"]}
]

Answer 1

您可以使用此方法从用户中找到资源和相关活动：

public ILookup<string,string> GetResourcesAndActivitiesByUser(string userName)
{
        using (var _db = new AppDbContext())
        {
            return (from u in _db.Users
                    where u.UserName == userName
                    from a in _db.Activities
                    join ra in _db.RoleResourceActivities on a.Id equals ra.ActivityId
                    join r in _db.Resources on ra.ResourceId equals r.Id
                    join ro in _db.Roles on ra.RoleId equals ro.Id
                    where u.Roles.Contains(ro)
                    select new { Resource = r.Name, Activity = a.Name })
                    .ToLookup(e => e.Resource, e => e.Activity);
        }
}

如果您要在问题中显示的匿名类型中创建IEnumerable<>，则可以执行以下操作：

 var resources = GetResourcesAndActivitiesByUser("UserX").Select(e=>new {Resource=e.Key,Activities=e.ToList()});