Я не могу понять, как определить объект, используемый в моем запросе группировки LINQ, чтобы они могли быть строго типом.Строгий ввод запроса LINQ с использованием нескольких ключей сложных объектов
Я построил запрос группировки, который использует два сложных объекта в качестве ключей. Запрос работает, но я хотел бы иметь возможность объявить тип возвращаемого объекта.
У меня есть сложный тип ...
Public Class Student
Public Name As IndividualsName
Public EnrolledSchool As School
Public BirthHospital As BirthPlace
Public Grade As Integer
Public Sub New(ByVal name As IndividualsName, ByVal enrolledSchool As School, ByVal birthHospital As BirthPlace, ByVal grade As Integer)
Me.Name = name
Me.EnrolledSchool = enrolledSchool
Me.BirthHospital = birthHospital
Me.Grade = grade
End Sub
End Class
Public Class School
Inherits Location
Public Sub New(ByVal name As String, ByVal city As String, ByVal state As String)
MyBase.New(name, city, state)
End Sub
Public Shared Function GetMyHS() As School
Return New School("My High School", "My City", "My State")
End Function
Public Shared Function GetYourHS() As School
Return New School("Your High School", "Your City", "Your State")
End Function
Public Shared Function GetMyElementry() As School
Return New School("My Elementary", "My City", "My State")
End Function
Public Shared Function GetMyMiddleSchool() As School
Return New School("My Middle School", "My City", "My State")
End Function
End Class
Public Class IndividualsName
Public First As String
Public Last As String
Public Sub New(ByVal first As String, ByVal last As String)
Me.First = first
Me.Last = last
End Sub
Public Overrides Function ToString() As String
Return First & " " & Last
End Function
End Class
Public Class BirthPlace
Inherits Location
Public Sub New(ByVal name As String, ByVal city As String, ByVal state As String)
MyBase.New(name, city, state)
End Sub
Public Shared Function GetMyHospital() As BirthPlace
Return New BirthPlace("My General Hospital", "My City", "My State")
End Function
Public Shared Function GetYourHospital() As BirthPlace
Return New BirthPlace("Your General Hospital", "Your City", "Your State")
End Function
End Class
Public Class Location
Public Name As String
Public City As String
Public State As String
Public Sub New(ByVal name As String, ByVal city As String, ByVal state As String)
Me.Name = name
Me.City = city
Me.State = state
End Sub
Public Overrides Function Equals(ByVal obj As Object) As Boolean
Return Me.GetHashCode = obj.GetHashCode
End Function
Public Overrides Function GetHashCode() As Integer
Dim returnValue As Integer
returnValue = Me.Name.GetHashCode() Xor Me.City.GetHashCode() Xor Me.State.GetHashCode()
Return returnValue
End Function
End Class
То, что я собираю в списке и группировка вместе на основе двух сложных ключей.
Sub Main()
Dim students As List(Of Student) = New List(Of Student)
students.Add(New Student(New IndividualsName("Bill", "Jones"), School.GetMyHS(), BirthPlace.GetMyHospital(), 9))
students.Add(New Student(New IndividualsName("George", "Jamesen"), School.GetMyHS(), BirthPlace.GetMyHospital(), 11))
students.Add(New Student(New IndividualsName("Chris", "McCartney"), School.GetYourHS(), BirthPlace.GetMyHospital(), 9))
students.Add(New Student(New IndividualsName("Sara", "Smith"), School.GetMyMiddleSchool(), BirthPlace.GetMyHospital(), 7))
students.Add(New Student(New IndividualsName("Josh", "Jefferies"), School.GetMyMiddleSchool(), BirthPlace.GetYourHospital(), 8))
students.Add(New Student(New IndividualsName("Mel", "Tompson"), School.GetMyHS(), BirthPlace.GetMyHospital(), 12))
students.Add(New Student(New IndividualsName("Jill", "Schmidt"), School.GetYourHS(), BirthPlace.GetMyHospital(), 10))
students.Add(New Student(New IndividualsName("Beth", "Taylor"), School.GetMyElementry(), BirthPlace.GetMyHospital(), 5))
students.Add(New Student(New IndividualsName("Mark", "Thatcher"), School.GetMyElementry(), BirthPlace.GetMyHospital(), 4))
students.Add(New Student(New IndividualsName("Tom", "Jones"), School.GetMyHS(), BirthPlace.GetYourHospital(), 9))
students.Add(New Student(New IndividualsName("Kevin", "Woo"), School.GetMyMiddleSchool(), BirthPlace.GetYourHospital(), 7))
Dim groupedQuery 'As IEnumerable(Of IGrouping())
groupedQuery = From student In students _
Group student By student.EnrolledSchool, student.BirthHospital Into Group _
Select EnrolledSchool, BirthHospital, StudentGroup = Group
For Each groupItem In groupedQuery
Console.WriteLine(String.Format("School: {0}, Birth Place: {1}", groupItem.EnrolledSchool.Name, groupItem.BirthHospital.Name))
'Console.WriteLine(String.Format("Group Item is type {0}.", groupItem.GetType()))
For Each item As Student In groupItem.StudentGroup
Console.WriteLine(String.Format("Name: {0} - Grade: {1}", item.Name.ToString(), item.Grade.ToString()))
Next
Next
End Sub
Все работает, но меня беспокоит, что когда я обрабатываю сбор данных, все объявляется анонимно. Это особенно назойливый объект, который создает сгруппированный список, находится в одной сборке, и он потребляется в веб-службе и на веб-сайте.
Я бы очень хотел, чтобы у вас был сильный тип возвращаемого IEnumberable, но я не могу понять, как объявить мой IGrouping interface.
я должен быть в состоянии пробежать свою структуру данных, как ...
Dim groupedQuery As IEnumerable(Of IGrouping(Of IDoNotKnowHowToDeclareMyComplexKey, Student))
groupedQuery = From student In students _
Group student By student.EnrolledSchool, student.BirthHospital Into Group _
Select EnrolledSchool, BirthHospital, StudentGroup = Group
For Each groupItem As IGrouping(Of IDoNotKnowHowToDeclareMyComplexKey, Student) In groupedQuery
Console.WriteLine(String.Format("School: {0}, Birth Place: {1}", groupItem.Key.Name)
For Each item As Student In groupItem
Console.WriteLine(String.Format("Name: {0} - Grade: {1}", item.Name.ToString(), item.Grade.ToString()))
Next
Next
, но я до сих пор не удалось выяснить, как объявить мой тип IGrouping.
Отлично. Это именно то, что я искал. –