linq 查询将在一次调用中返回单个值和一个列表

Question

我有这个 linq 调用：

PropertyViewModel propertyModel = null;
    propertyModel = (from property in db.LoanProperties
                    join tenant in db.Tenants
                    on property.PropertyId equals tenant.PropertyId
                    where property.LoanApplicationId == newApplication.LoanId
                    select new PropertyViewModel(
                        propertyModel.AddressLine1 = property.AddressLine1,
                        propertyModel.AddressLine2 = property.AddressLine2,
                        propertyModel.TotalRentPerAnnum = property.TotalRentPerAnnum,
                        propertyModel.Tenants = db.Tenants.Where(s => s.PropertyId == property.PropertyId).ToList()
                        ));

我的视图模型：

public class PropertyViewModel
    {
        public string AddressLine1 { get; set; }
        public string AddressLine2 { get; set; }
        public decimal? TotalRentPerAnnum { get; set; }
        public List<TenantViewModel> Tenants { get; set; }
    }

我想从我的 TenantViewModel 中的 linq 查询中转换属性下的租户。

我怎样才能做到这一点？

我指的是propertyModel.Tenants的最后一行。

Answer 1

这是我的第一个答案！希望对您有所帮助：

Tenants 和 LoanProperties 对象必须具有带有外键 PropertyId 的 navigation property。因此，LoanProperties 对象必须有一个租户列表。

我更喜欢您在最后一行使用的lambda expressions（干净/清晰的代码）。 试试这个：

var propertyModel = db.LoanProperties
        .Where(p => p.LoanApplicationId == newApplication.LoanId)
        .Select(p => new PropertyViewModel(){
                AddressLine1 = p.AddressLine1,
                AddressLine2 = p.AddressLine2,
                TotalRentPerAnnum = p.TotalRentPerAnnum,
                Tenants = p.Tenants.Select(t=> new TenantViewModel(){TenantType = t.TenantType , //other properties...})
                })
                //you don't have to query again, the tenants are already in the LoanProperty objects
                //you just have to transform it on ViewModel with a Select
        .FirstOrDefault();

另外，在你的PropertyViewModel的构造方法中，你不必把propertyModel.--- = ----.写进去也没用。

Answer 2

希望我正确理解了您的问题。我猜您正在寻找将您的租户数据库对象与您的 TenantViewModel 映射？

ropertyViewModel propertyModel = null;
    propertyModel = (from property in db.LoanProperties
                    join tenant in db.Tenants
                    on property.PropertyId equals tenant.PropertyId
                    where property.LoanApplicationId == newApplication.LoanId
                    select new PropertyViewModel(
                        propertyModel.AddressLine1 = property.AddressLine1,
                        propertyModel.AddressLine2 = property.AddressLine2,
                        propertyModel.TotalRentPerAnnum = property.TotalRentPerAnnum,
                        propertyModel.Tenants = db.Tenants.Where(s => s.PropertyId == property.PropertyId).Select(t => new TenantViewModel {//map your properties}).ToList()
                        ));