如何将 linq 数据绑定到模型类

Question

我有以下查询，

var userTree = (from user in users
join location in locations on user.FkHomeLocationId equals location.LocationId
join region in regions on location.RegionId equals region.LocationId
group region by new {
    Regionid = region.LocationId,
    location.LocationId
}
into grp
select new {
    RegionName = regions.FirstOrDefault(s = >s.LocationId == grp.Key.Regionid).LocationName,
    Branches = new {
        BranchName = locations.FirstOrDefault(b = >b.RegionId == grp.Key.Regionid).LocationName,
        Users = users.Where(u = >u.FkHomeLocationId == grp.Key.LocationId).Select(s = >new {
            FullName = s.FirstName + " " + s.LastName
        }).ToList()
    }
}).ToList();

我想将查询结果绑定到模型中。我怎样才能做到这一点。我创建了以下类模型来实现这一点，

public class TreeModel
    {
        public string RegionName { get; set; }
        public Branch Branchs { get; set; }
    }

    public class Branch
    {
        public string BranchName { get; set; }
        public List<User> Users { get; set; }
    }

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

现在需要将上面的查询数据绑定到这个模型类吗？在不创建 Branch 和 User 类的情况下，有什么最好的方法吗？因为我的应用程序有另一个具有相同名称的类用户和分支，我觉得为查询数据绑定创建像这样的单独类有些内疚？我说的对吗？

更新：我尝试如下，

var userTree = (from user in users
join location in locations on user.FkHomeLocationId equals location.LocationId
join region in regions on location.RegionId equals region.LocationId
group region by new {
    Regionid = region.LocationId,
    location.LocationId
}
into grp
select new Application.Alerts.Models.AlertUserTreeViewModel() {
    RegionName = regions.FirstOrDefault(s = >s.LocationId == grp.Key.Regionid).LocationName,
    Branchs = new Application.Alerts.Models.Branch() {
        BranchName = locations.FirstOrDefault(b = >b.RegionId == grp.Key.Regionid).LocationName,
        Users = new Application.Alerts.Models.User {
            FirstName = users.Where(u = >u.FkHomeLocationId == grp.Key.LocationId).FirstOrDefault().FirstName
        }
    }
}).ToList();

但是我在这一行遇到编译错误，

Users = new Application.Alerts.Models.User {
    FirstName = users.Where(u = >u.FkHomeLocationId == grp.Key.LocationId).FirstOrDefault().FirstName
}

作为

无法将类型“Alerts.Models.User”隐式转换为“System.Collections.Generic.List”

Answer 1

只需向您的匿名类添加额外的 FirstName 属性

var userTree = 
....
select new {
    RegionName = ...
    Branches = new {
        BranchName = ...,
        Users = ....Select(s = >new {
            FirstName=s.FirstName,
            FullName = s.FirstName + " " + s.LastName
        }).ToList()
    }

之后你可以创建视图模型

var treeModel= userTree.Select( new TreeModel {
                RegionName = userTree.RegionName
                Branchs =userTree.Branches.Select(i=> 
                new Branch { 
                 BranchName= i.BranchName,
                 Users= i.Users.Select(j=> new User{ FirstName=j.Firstname})
                )});

如果你只需要你的 userTree 中的全名，你可以转换回来

userTree= userTree.Select( new TreeModel {
                RegionName = userTree.RegionName
                Branchs =userTree.Branches.Select(i=> 
                new Branch { 
                 BranchName= i.BranchName,
                 Users= i.Users.Select( j=> new {j.FullName})
                )});

更新

如果你想使用 dbcontext 运行另一个查询，你可以试试这个

var userTree = (from user in users
join location in locations on user.FkHomeLocationId equals location.LocationId
join region in regions on location.RegionId equals region.LocationId
group region by new {
    Regionid = region.LocationId,
    location.LocationId
}
into grp
select new Application.Alerts.Models.AlertUserTreeViewModel {
    RegionName = regions.FirstOrDefault(s = >s.LocationId == grp.Key.Regionid).LocationName,
    Branches = new new Application.Alerts.Models.Branch {
         BranchId = locations.FirstOrDefault(b = >b.RegionId == 
        grp.Key.Regionid).LocationId,
        BranchName = locations.FirstOrDefault(b = >b.RegionId == grp.Key.Regionid).LocationName,
        Users = users.Where(u = >u.FkHomeLocationId == grp.Key.LocationId).Select(s = >new  User {
             Id=s.Id,
             LastName=s.LastName,
            FirstName= s.FirstName 
        }).ToList()
    }
}).ToList();

Answer 2

您的Branch 有一个List<User>，但您试图实例化为User，这就是您收到错误的原因。使用下面的代码。

Users = users.Where(u = >u.FkHomeLocationId == grp.Key.LocationId).Select(u => new User { FirstName = u.FirstName }).ToList()