asp.net - Entity Framework 核心 : issue with Contains method

Question

有我的简化数据库模型:

public class Chat
{
public ICollection<ApplicationUser> Users {get; set;} //nav property - represents participants of a chat
}

public class ApplicationUser : IdentityUser // it represents a net-identity user; it does not have any references to chats
{...}

因此，在 Controller 的类(class)中，我尝试进行聊天，例如将当前用户包含为参与者:

var user = GetUser();
_context.Chats.Where(chat => chat.Users.Contains(user)).ToList();

此代码引发异常:

You can not use the type of expression ...ApplicationUser for parameter's type "Microsoft.EntityFrameworkCore.Storage.ValueBuffer" of method "Boolean Contains[ValueBuffer](System.Collections.Generic.IEnumerable`1[Microsoft.EntityFrameworkCore.Storage.ValueBuffer], Microsoft.EntityFrameworkCore.Storage.ValueBuffer)"

这里有什么问题？

Answer 1

你需要使用 Any()，就像这样

 var chatsList =_context.Chats.Where(chat => chat.Users.Any(u => u.id== user.id)).ToList();