C#：基于公共标识符合并两个对象？答案

【问题标题】：C#: Merge two objects based on common identifier?C#：基于公共标识符合并两个对象？
【发布时间】：2020-04-09 09:44:15
【问题描述】：

我有一个 POCO 类，其中的嵌套类定义如下：

class Company 
{  
   string CompanyName { get; set; }
   List<Server> Servers { get; set; }
}

class Server 
{
   int ServerId { get; set;}
   string ServerName { get; set; }
   List<User> Users { get; set; }
}

class User
{
   string FirstName { get; set; }
   string LastName { get; set; }
}

假设我用以下数据实例化了它：

CompanyName = "Company A";
Servers =    
   ServerId = 134;
   ServerName = HOST01;
   Users =
      FirstName = "John";
      LastName = "Smith";
      FirstName = "Bob";
      LastName = "Jones";

   ServerId = 232;
   ServerName = HOST31;
   Users = 
      FirstName = "Michael";
      LastName = "Stevens";

   ServerId = 134;
   ServerName = HOST01;
   Users =
      FirstName = "Larry";
      LastName = "Edwards";
      FirstName = "Craig";
      LastName = "White";

如何根据匹配的“ServerId”属性将所有用户合并在一起？基本上，我怎么能把它变成这个？

CompanyName = "Company A";
Servers =    
   ServerId = 134;
   ServerName = HOST01;
   Users =
      FirstName = "John";
      LastName = "Smith";
      FirstName = "Bob";
      LastName = "Jones";
      FirstName = "Larry";
      LastName = "Edwards";
      FirstName = "Craig";
      LastName = "White"; 

   ServerId = 232;
   ServerName = HOST31;
   Users = 
      FirstName = "Michael";
      LastName = "Stevens";

【问题讨论】：

同一用户是否可以存在于多个“服务器”和/或公司中？
是的。用户可以跨越服务器和公司

标签： c# sorting inner-classes

【解决方案1】：

使用 LINQ GroupBy 对ServerId 进行分组，并假设具有相同 id 的服务器也具有相同的名称。

var grouped = Companies // IEnumerable<Company>
    .Select(c => new Company
    {
        CompanyName = c.CompanyName,
        Servers = c.Servers
            .GroupBy(s => s.ServerId)
            .Select(grp => new Server
            {
                ServerId = grp.Key,
                ServerName = grp.First().ServerName,
                Users = grp.SelectMany(s => s.Users)).ToList()
            })
    });

【讨论】：

【解决方案2】：

您可以使用Linq，如以下代码：

1 - 通过 id 和 name 获取不同的服务器：

List<Server> distinctServers = company.Servers
    .GroupBy(s => new { s.ServerId, s.ServerName })
    .Select(s => new Server
    {
        ServerId = s.Key.ServerId,
        ServerName = s.Key.ServerName,
        Users = s.SelectMany(x => x.Users).ToList()
    }).ToList();

2 - 建立新公司或使用旧公司：

Company result = new Company
{
    CompanyName = company.CompanyName,
    Servers = distinctServers
};
// or   
company.Servers = distinctServers;

如果你有公司列表，你可以在select函数中使用相同的代码：

List<Company> companies = new List<Company> { company };
List<Company> companiesWithDistinctServers = companies
    .Select(c => new Company
    {
        CompanyName = c.CompanyName,
        Servers = c.Servers.GroupBy(s => new { s.ServerId, s.ServerName })
            .Select(s => new Server
            {
                ServerId = s.Key.ServerId,
                ServerName = s.Key.ServerName,
                Users = s.SelectMany(x => x.Users).ToList()
            }).ToList()
    }).ToList();

希望对你有帮助

【讨论】：