序列化linq结果时出错

Question

我尝试以这种方式序列化LINQ结果：

Private Sub btnXML_Click(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles btnXML.Click  
    Try  
        Dim sourceForXML = From detail In PayrollRegisterModel.CompanyDetails  
                           Join shifts In PayrollRegisterModel.Shifts On   detail.Id_companydetail Equals shifts.Id_companydetail  
        Dim xmlFile As New Xml.Serialization.XmlSerializer(sourceForXML.GetType)  
        Dim xw As System.Xml.XmlWriter = Xml.XmlWriter.Create("C:/Abcom/XMLRegister.xml")  
        xmlFile.Serialize(xw, sourceForXML)  
    Catch ex As Exception  
        MsgBox(e.ToString)  
    End Try  
End Sub  

但在这条线上：

        Dim xmlFile As New Xml.Serialization.XmlSerializer(sourceForXML.GetType) 

我得到了这个错误：

**System.InvalidOperationException was caught
  Message=To be XML serializable, types which inherit from IEnumerable must have an implementation of Add(System.Object) at all levels of their inheritance hierarchy. System.Data.Objects.ObjectQuery`1[[VB$AnonymousType_0`2[[Abcom.Payroll.Register.CompanyDetail, Abcom.Payroll.Register, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null],[Abcom.Payroll.Register.Shift, Abcom.Payroll.Register, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], Abcom.Payroll.Register, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]] does not implement Add(System.Object).
  Source=System.Xml
  StackTrace:
       at System.Xml.Serialization.TypeScope.GetEnumeratorElementType(Type type, TypeFlags& flags)
       at System.Xml.Serialization.TypeScope.ImportTypeDesc(Type type, MemberInfo memberInfo, Boolean directReference)
       at System.Xml.Serialization.TypeScope.GetTypeDesc(Type type, MemberInfo source, Boolean directReference, Boolean throwOnError)
       at System.Xml.Serialization.ModelScope.GetTypeModel(Type type, Boolean directReference)
       at System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(Type type, XmlRootAttribute root, String defaultNamespace)
       at System.Xml.Serialization.XmlSerializer..ctor(Type type, String defaultNamespace)
       at System.Xml.Serialization.XmlSerializer..ctor(Type type)
       at Abcom.Payroll.Register.MainWindow.btnXML_Click(Object sender, RoutedEventArgs e) in C:\Abcom\Inhouse Development Tools\Abcom.Payroll.Register\Abcom.Payroll.Register\MainWindow.xaml.vb:line 415**

有人知道这是怎么回事吗?我该如何解决这个问题？

致以敬意，

克劳迪奥

Answer 1

奇怪的是，您想序列化的。但是如果你愿意:只需将.ToList()添加到你的sourceForXML中，它就会被序列化。但结果会很奇怪。(不知道方法扩展在VB中是否可用，如果没有，则使用Enumerable.ToList( /* From .... Join ... here */))

Imho，一个好的解决方案是不使用匿名类型进行序列化。使用需要保存的属性创建类，然后使用linq创建该项目的列表，并在序列化该集合之后。在C#中，它类似于：

class DataForXml
{
    public string Field1 {get; set;}
    public string Filed2 {get; set;}
    // other needed fields here
}

您的方法应该将所需的信息提取到该类的实例中：

var xmlData = PayrollRegisterModel.CompanyDetails
       .Join(/* other table */) 
       .Select(x => new DataForXml { Field1 = x.Field1, Field2 = x.Field2 /* init other props here*/})
       .ToList();