循环实体引用是正确的方法吗？

发布于 2024-08-26 11:51:53 字数 651 浏览 9 评论 0原文

我想让所有对用户名列表具有特定角色的用户。

正在使用 .Ininclude 包含所有用户，并遍历 UsersReference 循环遍历与该角色关联的所有用户的最佳方法？

我注意到我无法执行 foreach(User user in role.Users) 但 UsersReference 似乎可以工作，但这是应该如何完成的？浏览参考文献？

using (var context = new MyEntities())
        {
            List<string> users = new List<string>();

            Role role = (from r in context.Roles.Include("Users")
                        where r.RoleName == roleName
                        select r).FirstOrDefault();

            foreach (User user in role.UsersReference)
                users.Add(user.UserName);

            return users.ToArray();
        }

原文

I want to get all users that have a specific role to a list of usernames.

Is using .Include to include all the users, and going through the UsersReference
the best way to loop through all the users that are associated with the role?

I noticed I could not do a foreach(User user in role.Users) but UsersReference seem to work, but is that how it's supposed to be done? Going through the reference?

using (var context = new MyEntities())
        {
            List<string> users = new List<string>();

            Role role = (from r in context.Roles.Include("Users")
                        where r.RoleName == roleName
                        select r).FirstOrDefault();

            foreach (User user in role.UsersReference)
                users.Add(user.UserName);

            return users.ToArray();
        }

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倾｀听者〃 2024-09-02 11:51:53

您的 Role 表是否有可能具有 Users 属性？我认为它将命名导航属性 Users，而不是 UsersReference。我不使用 EF，但我见过的所有示例都在表之后命名属性。 AFAIK 它总是实现 IEnumerable 所以你应该能够在 foreach 中使用它。

如果你设置正确，我想你只需要：

using (var context = new MyEntities())
{
    return context.Roles
                  .Where( r => r.RoleName == roleName )
                  .SelectMany( r => r.Users )
                  .Select( u => u.UserName )
                  .ToArray();
}

Is it possible that your Role table has a Users property? I would think that it would name the navigation property Users, not UsersReference. I don't use EF, but all the examples I've seen name the property after the table. AFAIK it always implements IEnumerable so you should be able use it in a foreach.

If you have it set up right I think you only need:

using (var context = new MyEntities())
{
    return context.Roles
                  .Where( r => r.RoleName == roleName )
                  .SelectMany( r => r.Users )
                  .Select( u => u.UserName )
                  .ToArray();
}

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空‖城人不在 2024-09-02 11:51:53

尝试将原始 foreach 循环与 ToList()

foreach(var user in role.Users.ToList()) {...} 一起使用

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夏至、离别 2024-09-02 11:51:53

请改用 .ToArray() 帮助程序。

using (var context = new MyEntities())
{
    return (from role in context.Roles
            where role.RoleName == roleName
            from user in r.Users
            select user.UserName).ToArray();
}

请注意，如果您这样做，则不需要 .Include("Users")。在查询中使用 r.Users 会使其出现在一个查询中，而无需包含它，因为它是在活动的 ObjectContext 中使用的。

附带说明一下，我不确定此方法的方法签名是什么，但在这种情况下 IEnumerable 可能比 string[] 更合适，因为您可以稍后调整实现，而无需从其他类型的集合创建数组。

Use the .ToArray() helper instead

using (var context = new MyEntities())
{
    return (from role in context.Roles
            where role.RoleName == roleName
            from user in r.Users
            select user.UserName).ToArray();
}

Note that there's no need for .Include("Users") if you do it this way. Using r.Users in the query causes it to be in one query without the need for including it, because it's used in an active ObjectContext.

One a side note, I'm not sure what the method signature of this method is, but in this case IEnumerable<string> is probably a better fit than string[], because you can adjust the implementation later without creating arrays from other types of collections.

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