[英]SelectList in QueryOver
我在通過 QueryOver 選擇時遇到了一些問題,這是我的模型類:
public class BaseModel
{
public virtual int Id { get; set; }
public virtual DateTime ModifyDate { get; set; }
public virtual DateTime CreateDate { get; set; }
public virtual User CreateUser { get; set; }
public virtual User ModifyUser { get; set; }
public virtual bool IsActive { get; set; }
}
public class BaseClassMap<T> : ClassMap<T> where T : BaseModel
{
public BaseClassMap()
{
Id(x => x.Id).GeneratedBy.Identity();
References(x => x.CreateUser, "CreateUser_Id");
References(x => x.ModifyUser, "ModifyUser_Id");
Map(x => x.CreateDate).Not.Nullable().Default("GETDATE()");
Map(x => x.ModifyDate).Not.Nullable().Default("GETDATE()"); ;
Map(x => x.IsActive).Not.Nullable().Default("1");
}
}
public class Expenditure : BaseModel
{
public virtual decimal Amount { get; set; }
public virtual Category Category { get; set; }
public virtual string Comment { get; set; }
public virtual DateTime Month { get; set; }
}
public class ExpenditureMap : BaseClassMap<Expenditure>
{
public ExpenditureMap()
{
Schema("[budget]");
Table("[Expenditure]");
Id(x => x.Id);
Map(x => x.Amount).Not.Nullable();
Map(x => x.Comment);
Map(x => x.Month).Not.Nullable();
References(x => x.Category, "Category_Id").Not.Nullable();
}
}
public class User : BaseModel
{
public virtual string Login { get; set; }
public virtual string Email { get; set; }
public virtual string Password { get; set; }
public virtual string PasswordSalt { get; set; }
public virtual string HashAlgorithm { get; set; }
}
public class UserMap : BaseClassMap<User>
{
public UserMap()
{
Schema("[permission]");
Table("[User]");
Id(x => x.Id);
Map(x => x.Login).Not.Nullable();
Map(x => x.Email).Not.Nullable();
Map(x => x.Password).Not.Nullable();
Map(x => x.PasswordSalt);
Map(x => x.HashAlgorithm).Not.Nullable();
}
}
public class ExpenseDetailsItemVm
{
public int Id { get; set; }
public string Comment { get; set; }
public decimal Amount { get; set; }
public DateTime CreateDate { get; set; }
public string CreateUser { get; set; }
}
這是我的查詢:
var user = new User();
var result = new ExpenseDetailsItemVm();
var expenses = SessionManager.Session.QueryOver<Expenditure>()
.JoinAlias(x => x.CreateUser, () => user)
.Where(x => x.IsActive &&
x.Category.Id == categoryId &&
x.Month == date.ToFirstDayOfMonth())
.SelectList(list => list
.Select(x => x.Id).WithAlias(() => result.Id)
.Select(x => x.Amount).WithAlias(() => result.Amount)
.Select(x => x.Comment).WithAlias(() => result.Comment)
.Select(x => x.CreateDate).WithAlias(() => result.CreateDate)
.Select(()=> user.Login).WithAlias(() => result.CreateUser)
).TransformUsing(Transformers.AliasToBean<ExpenseDetailsItemVm>())
.List<ExpenseDetailsItemVm>();
我收到此錯誤:
你調用的對象是空的。
我確定這行代碼的問題:
.Select(()=> user.Login).WithAlias(() => result.CreateUser)
如果我注釋掉這一行,查詢就可以正常工作並返回結果而不會出錯。
為了消除映射錯誤,我嘗試了這個:
var u = SessionManager.Session.QueryOver<User>().Where(x => x.Id == 1).
SelectList(list => list.
Select(x => x.Login).WithAlias(() => result.CreateUser))
.TransformUsing(Transformers.AliasToBean<ExpenseDetailsItemVm>())
.List<ExpenseDetailsItemVm>();
這也很好用。
在我的Expenditure
表中,列CreateUser_Id
處處都有一個值
嘗試將用作別名的對象用作 null:
User user = null;
ExpenseDetailsItemVm result = null;
因為它們僅用於創建具有強類型語法的 SQL。
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