我是新来的链接，这是我使用它的第一个任务，并且进展不顺利。 我有一个页面可以按照所点击的列进行排序。 其中一列是Date列，DateSubmitted。
我收到的对象错误未设置为对象的实例...
我逐步完成了代码，注意到list对象只包含值，直到它通过了orderby行代码。我认为这是因为dateAccepted属性包含空值，就在assignemnt data = data.OrderBy ...之前，数据保存416条记录，在通过赋值后，它有null，并抛出错误。
我有另外一个类似于这个的问题，我为重复道歉，但我真的需要一些解释，如果可能的话，以及如何解决这个问题的一些帮助。
我尝试在dateAccepted之后添加HasValue，但这没有什么区别。
任何帮助都很有价值。非常感谢你。
var data = (from c in starter
select new ACPListObject()
{
contact = c,
Year = Year,
LastSentDate = (from s in c.smsContactFormSents orderby s.sentDateTime descending select s.sentDateTime).FirstOrDefault(),
LastSubmit = (from s in c.smsContactFormSents orderby s.sentDateTime descending select s.ACPForm).FirstOrDefault(),
lastFormComplete = (from s in c.smsContactFormSents orderby s.sentDateTime descending select s).FirstOrDefault(),
isMyContact = (from m in c.smsEmployeeContacts where m.empID == userID select m).Any()
});
if (isCurrentYear)
{
var custs = (from c in emptyCustomers.ToList()
where c.ISCTBillingActive || c.ISFFDMBillingActive || c.IsMRIBillingActive || (c.IsPETBillingActive && c.custType != 2)
select new ACPListObject()
{
contact = new smsCustomerContact() { cntID = -1, smsCustomer = c, cntActive = true },
Year = Year,
LastSentDate = new DateTime(),
LastSubmit = (ACPForm)null,
lastFormComplete = (smsContactFormSent)null,
isMyContact = false
});
var combined = data.ToList();
combined.AddRange(custs);
data = combined.AsQueryable();
}
else if (sortColumn == "DateSubmitted")
{
if (asc)
{
data = data.OrderBy(o => o.lastFormComplete.ACPForm.dateAccepted);
}
else
{
data = data.OrderByDescending(o => o.lastFormComplete.ACPForm.dateAccepted);
}
}
return data.ToList();
}
EDIT 我尝试了你提出的解决方案，我认为它正在工作，但由于某种原因，dateAccepted即“dateSubmitted”的值没有被填充。
他们的方式是在代码中连接对象以获得dateAccepted是这样的：
ACPListObject
public class ACPListObject
{
public smsCustomerContact contact { get; set; }
public int Year { get; set; }
public DateTime LastSentDate { get; set; }
public ACPForm LastSubmit { get; set; }
public DateTime? dateAccepted { get; set; }
public smsContactFormSent lastFormComplete { get; set; }
public bool isMyContact { get; set; }
}
smsContactFormSent
public partial class smsContactFormSent
{
public System.Guid ID { get; set; }
public int cntID { get; set; }
public int sentBy { get; set; }
public System.DateTime sentDateTime { get; set; }
public bool completed { get; set; }
public Nullable<int> acpID { get; set; }
public virtual ACPForm ACPForm { get; set; }
public virtual smsCustomerContact smsCustomerContact { get; set; }
public virtual smsEmployee smsEmployee { get; set; }
}
public partial class ACPForm
{
public ACPForm()
{
this.ACPFormContacts = new HashSet<ACPFormContact>();
this.smsContactFormSents = new HashSet<smsContactFormSent>();
}
public int acpID { get; set; }
public int romID { get; set; }
public int customerID { get; set; }
public Nullable<System.DateTime> dateSent { get; set; }
public Nullable<System.DateTime> dateAccepted { get; set; }
}
可能是因为我没有正确访问smsContactFormSent而没有获取值吗？
这就是我实施解决方案的方式：
public class ACPListObject
{
public smsCustomerContact contact { get; set; }
public int Year { get; set; }
public DateTime LastSentDate { get; set; }
public ACPForm LastSubmit { get; set; }
public DateTime? dateAccepted { get; set; }
public smsContactFormSent lastFormComplete { get; set; }
public bool isMyContact { get; set; }
}
var data = (from c in starter
select new ACPListObject()
{
contact = c,
Year = Year,
LastSentDate = (from s in c.smsContactFormSents orderby s.sentDateTime descending select s.sentDateTime).FirstOrDefault(),
LastSubmit = (from s in c.smsContactFormSents orderby s.sentDateTime descending select s.ACPForm).FirstOrDefault(),
lastFormComplete = (from s in c.smsContactFormSents orderby s.sentDateTime descending select s).FirstOrDefault(),
dateAccepted = (from s in c.smsContactFormSents orderby s.sentDateTime descending select s.ACPForm.dateAccepted).FirstOrDefault(), //note that I am selecting dateAccept here so, this will be a DateTime or null
isMyContact = (from m in c.smsEmployeeContacts where m.empID == userID select m).Any()
});
else if (sortColumn == "DateSubmitted")
{
if (asc)
{
//data = data.OrderBy(o => o.lastFormComplete.ACPForm.dateAccepted);
data = data.OrderBy(o => o.dateAccepted);//order by new variable
}
else
{
//data = data.OrderByDescending(o => o.lastFormComplete.ACPForm.dateAccepted);
data = data.OrderByDescending(o => o.dateAccepted); //order by new variable
}
}
发送新的ContactForm时，不会填充dateSubmitted的值。我保持diggin，看看错误是否来自其他地方。非常感谢你对Marcos的帮助。
答案 0 :(得分：1)
检查此解决方案并适应您的模型。
var data = (from c in starter
select new ACPListObject()
{
contact = c,
Year = Year,
LastSentDate = (from s in c.smsContactFormSents orderby s.sentDateTime descending select s.sentDateTime).FirstOrDefault(),
LastSubmit = (from s in c.smsContactFormSents orderby s.sentDateTime descending select s.ACPForm).FirstOrDefault(),
lastFormComplete = (from s in c.smsContactFormSents orderby s.sentDateTime descending select s).FirstOrDefault(),
dateAccepted = (from s in c.smsContactFormSents orderby s.sentDateTime descending select s.ACPForm.dateAccepted).FirstOrDefault(), //note that I am selecting dateAccept here so, this will be a DateTime or null
isMyContact = (from m in c.smsEmployeeContacts where m.empID == userID select m).Any()
});
if (isCurrentYear)
{
var custs = (from c in emptyCustomers.ToList()
where c.ISCTBillingActive || c.ISFFDMBillingActive || c.IsMRIBillingActive || (c.IsPETBillingActive && c.custType != 2)
select new ACPListObject()
{
contact = new smsCustomerContact() { cntID = -1, smsCustomer = c, cntActive = true },
Year = Year,
LastSentDate = new DateTime(),
LastSubmit = (ACPForm)null,
lastFormComplete = (smsContactFormSent)null,
isMyContact = false
});
var combined = data.ToList();
combined.AddRange(custs);
data = combined.AsQueryable();
}
else if (sortColumn == "DateSubmitted")
{
if (asc)
{
data = data.OrderBy(o => o.dateAccepted);//order by new variable
}
else
{
data = data.OrderByDescending(o => o.dateAccepted); //order by new variable
}
}
return data.ToList();
编辑： 如果可能，您应该将dateAccepted添加到ACPListObject类：
public class ACPListObject
{
public smsCustomerContact contact { get; set; }
public int Year { get; set; }
public DateTime LastSentDate { get; set; }
public ACPForm LastSubmit { get; set; }
public smsContactFormSent lastFormComplete { get; set; }
public bool isMyContact { get; set; }
public DateTime? dateAccepted { get; set; }
}
如果您无法添加此属性，则此解决方案无效。如果这对您有用，请告诉我。