c# - 使用 Linq 从另一个具有匹配值的列表更新列表

Question

我希望在从另一个来源查询上下文时更新列表中的值

我可以找到 2 种不同风格的查询的匹配项

var r = from aa in context.Persons.GetItems()
        join bb in findPersonViewModel.findPersonResultsViewModel on aa.PersonId equals bb.PersonID
        select aa;

或

var results = context.Persons.GetItems().Where(ax => findPersonViewModel.findPersonResultsViewModel.Any(b => ax.PersonId == b.PersonID));

为了简单起见，我缩短了模型

public class FindPersonResultsViewModel
{
    public int PersonID { get; set; }
    public bool ExistInContactManager { get; set; }
    public bool ActionType { get; set; }
}

public class PersonViewModel
{
     public int PersonID { get; set; }
}

目标:如果 PersonID 匹配，则更新 FindPersonResultsViewModel 使 ExistinContactManager 和 ActionType 都为 True

这是一个视觉数据示例

var findPersonResultsViewModel = new List<FindPersonResultsViewModel>()
    { new FindPersonResultsViewModel { PersonID = 2, ActionType = false, ExistInContactManager = false },
      new FindPersonResultsViewModel { PersonID = 3, ActionType = false, ExistInContactManager = false },
      new FindPersonResultsViewModel { PersonID = 4, ActionType = false, ExistInContactManager = false },
      new FindPersonResultsViewModel { PersonID = 5, ActionType = false, ExistInContactManager = false },
      new FindPersonResultsViewModel { PersonID = 6, ActionType = false, ExistInContactManager = false },
    };



var personModel = new List<PersonViewModel>()
    { new PersonViewModel { PersonID = 2 },
      new PersonViewModel { PersonID = 6 },
      new PersonViewModel { PersonID = 8 },
      new PersonViewModel { PersonID = 9 },
      new PersonViewModel { PersonID = 12 },
      new PersonViewModel { PersonID = 22 },
      new PersonViewModel { PersonID = 32 },
      new PersonViewModel { PersonID = 42 },
    };

Answer 1

如果我明白你在问什么......你可以只使用 Contains 和一个 foreach

var ids = personModel.Select(x => x.PersonID);

var results = findPersonResultsViewModel.Where(x => ids.Contains(x.PersonID));

foreach (var item in results)
{
   item.ActionType = true;       
   item.ExistInContactManager = true
}

db.SaveChanges();

或者您可以通过使用 Join 节省自己的往返时间，并使用 foreach

进行更新

var results =
   from pr in findPersonResultsViewModel
   join p in personModel on pr.PersonID equals p.PersonID
   select pr;

foreach (var item in results)
{
   item.ActionType = true;
   item.ExistInContactManager = true;
}

db.SaveChanges();

输出

PersonID : 2, ActionType :True, ExistInContactManager :True
PersonID : 3, ActionType :False, ExistInContactManager :False
PersonID : 4, ActionType :False, ExistInContactManager :False
PersonID : 5, ActionType :False, ExistInContactManager :False
PersonID : 6, ActionType :True, ExistInContactManager :True

Full Demo here