将 LinQ 结果转换为强类型集合时出现问题

发布于 2024-09-28 11:07:35 字数 636 浏览 0 评论 0原文

我想这很微不足道，但对我来说不是。

我有一个集合MembershipUserCollection。我想对其执行一些 Linq 查询，因此我使用了 OfType() 方法，然后对其应用了 Where() 。但是，我不知道如何将结果转换回 MembershipUserCollection？

这是我的代码：

MembershipUserCollection Users;
Users = GetAllUsers(pageIndex, pageSize, out totalRecords).OfType<MembershipUser>().Where(user => user.Email == emailToMatch); //how to cast it back to MembershipUserCollection ?

GetAllUsers(pageIndex, pageSize, out totalRecords) 返回MembershipUserCollection

感谢您的宝贵时间。

原文

I guess this is trivial but not for me.

I have a collection MembershipUserCollection. I wanted to perform some Linq query over it so I've used OfType<MembershipUser>() method and then applied Where() on it. However, I do not know how to cast back my results to MembershipUserCollection?

This is my code:

MembershipUserCollection Users;
Users = GetAllUsers(pageIndex, pageSize, out totalRecords).OfType<MembershipUser>().Where(user => user.Email == emailToMatch); //how to cast it back to MembershipUserCollection ?

GetAllUsers(pageIndex, pageSize, out totalRecords) is returning MembershipUserCollection

Thanks for your time.

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顾忌 2024-10-05 11:07:35

我认为您不能在查询本身中执行此操作，但您应该能够执行此操作：（

var query = GetAllUsers(pageIndex, pageSize, out totalRecords)
                .OfType<MembershipUser>()
                .Where(user => user.Email == emailToMatch);

var users = new MembershipUserCollection();
foreach (var user in query)
{
    users.Add(user);
}

当然，如果您愿意，您可以将该逻辑包装到扩展方法中，然后在询问。）

I don't think you can do it in the query itself, but you should be able to do this:

var query = GetAllUsers(pageIndex, pageSize, out totalRecords)
                .OfType<MembershipUser>()
                .Where(user => user.Email == emailToMatch);

var users = new MembershipUserCollection();
foreach (var user in query)
{
    users.Add(user);
}

(And, of course, you could wrap that logic up into an extension method if you wanted and then call the extension method in the query.)

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本宫微胖 2024-10-05 11:07:35

可能的解决方案之一：

   var users = GetAllUsers(pageIndex, pageSize, out totalRecords)
      .OfType<MembershipUser>()
      .Where(user => user.Email == emailToMatch);

   MembershipUserCollection membershipUsers = new MembershipUserCollection();
   users
      .ToList()
      .ForEach(membershipUsers.Add);

另一种带有 foreach 语句的解决方案：

foreach (var user in users)
{
    membershipUsers.Add(user);
}

One of the possible solutions:

   var users = GetAllUsers(pageIndex, pageSize, out totalRecords)
      .OfType<MembershipUser>()
      .Where(user => user.Email == emailToMatch);

   MembershipUserCollection membershipUsers = new MembershipUserCollection();
   users
      .ToList()
      .ForEach(membershipUsers.Add);

Another one with foreach statement:

foreach (var user in users)
{
    membershipUsers.Add(user);
}

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看透却不说透 2024-10-05 11:07:35

所以这很简单，我只需这样投射：

MembershipUserCollection Users;
Users = (MembershipUserCollection)GetAllUsers(pageIndex, pageSize, out totalRecords).OfType<MembershipUser>().Where(user => user.Email == emailToMatch).Cast<MembershipUser>();

谢谢大家的回答。

So it was trivial, I just had to cast it like this:

MembershipUserCollection Users;
Users = (MembershipUserCollection)GetAllUsers(pageIndex, pageSize, out totalRecords).OfType<MembershipUser>().Where(user => user.Email == emailToMatch).Cast<MembershipUser>();

Thanks guys for your asnwers.

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