【发布时间】：2011-03-21 16:42:40
【问题描述】：
当学生登录时，我会为他们加载一个仪表板，让他们了解他们在住宿预订过程中所处的位置。不管我做什么，尽管它似乎总是触发 Else 条件，即使我在 For..Next 循环中有一个 Exit For 。这是有问题的代码：
Public Sub Initialize_Dashboard()
Dim term As String = CStr(Session("term"))
Dim year As String = CStr(Session("year"))
Dim people_code_id As String = CStr(Session("people_code_id"))
Dim class_level As String = CStr(Session("class"))
' %%%%%% Show the resident's name and whether they have a room. %%%%%%
Dim dbroom As New pbu_housingEntities
Dim queryStudent = From p In dbroom.Residents _
Where p.people_code_id = people_code_id _
Join b In dbroom.Buildings On p.building Equals b.id _
Join r In dbroom.Rooms On p.room Equals r.id
Select p, b, r
lblName.Text = CStr(Session("name"))
If queryStudent.Count.Equals(0) Then
lblRegistered.Text = "We do not have you currently registered for campus housing."
Else
lblRegistered.Text = "You are currently registered for " & queryStudent.First.b.building_name & " " & queryStudent.First.r.room1 & "."
End If
' Initiate variables to check for class settings.
Dim dbConfig As New pbu_housingEntities
Dim whatdatest = From p In dbConfig.Configs
Dim whatdatee = From p In dbConfig.Configs
' Add in a check for contract signatures.
Dim dbContracts As New pbu_housingEntities
Dim clcexists = From p In dbContracts.Signatures _
Where p.StudentID = people_code_id _
And p.ContractType = "clc" _
Order By p.ID Descending _
Select p
Dim rhcexists = From p In dbContracts.Signatures _
Where p.StudentID = people_code_id _
And p.ContractType = "rhc" _
Order By p.ID Descending _
Select p
' Shows or hides the buttons for contracts based on whether signatures exist.
Dim clcfirst = clcexists.FirstOrDefault()
Dim rhcfirst = rhcexists.FirstOrDefault()
If clcfirst Is Nothing Then
pnlSignCLC.Visible = True
Else
pnlSignCLC.Visible = False
End If
If rhcfirst Is Nothing Then
pnlSignRHC.Visible = True
Else
pnlSignRHC.Visible = False
End If
' Determine if the student is eligible to register for class.
Dim classes() As String = {"FR%", "SO", "JR", "SR", "SR5"}
For Each value As String In classes
' Pull in the dates the student should be able to register for this class, compare them to the current date.
Dim current_value = value
If class_level = current_value Then
Response.Write("hello")
whatdatest = From p In dbConfig.Configs _
Where p.Description = current_value + "OD" _
Select p
whatdatee = From p In dbConfig.Configs _
Where p.Description = current_value + "CD" _
Select p
' If the current date is within their registration period...
If Date.Now >= whatdatest.First.dateValue And Date.Now <= whatdatee.First.dateValue Then
Dim person_name As String = CStr(Session("person_name")) ' Must stay here or will conflict.
Dim hasroom = From p In dbConfig.Residents _
Where p.person_name = person_name _
Where p.semester = term _
Where p.year = year _
Select p
' If they have signed their contracts, lets let them register for a room.
If hasroom.Count.Equals(0) AndAlso clcfirst IsNot Nothing AndAlso rhcfirst IsNot Nothing Then
pnlBegin.Visible = True
btnBegin.Enabled = True
' If they are already registered for a room, let them delete their reservation.
ElseIf clcfirst IsNot Nothing AndAlso rhcfirst IsNot Nothing Then
pnlDelete.Visible = True
btnDelete.Enabled = True
Else
' In any other situation, we don't need to do anything.
' There really shouldn't be any other situation.
End If
' What to do if the current date is not within the room reservation window.
Exit For
Else
Dim class_name As String
Select Case current_value
Case "FR%"
class_name = "Freshman"
Case "SO"
class_name = "Sophmore"
Case "JR"
class_name = "Junior"
Case "SR"
class_name = "Senior"
Case "SR5"
class_name = "Fifth year Senior"
End Select
lblError.Text = "You are currently a " & current_value & ". You will be eligible to reserve a room between" _
& whatdatest.First.dateValue & " and " & whatdatee.First.dateValue & ". Please come back during those dates. Thanks!"
End If
Exit For
Else
' What to do if the user isn't assigned a class level at all!
lblError.Text = "Oops...Something might be wrong with our records. We don't have you registered for classes. Please contact Dave Mackey, x4543."
End If
Next
这是我将最后一个 else 子句移到单独的 If..Then 后的代码：
Public Sub Initialize_Dashboard()
Dim term As String = CStr(Session("term"))
Dim year As String = CStr(Session("year"))
Dim people_code_id As String = CStr(Session("people_code_id"))
Dim class_level As String = CStr(Session("class"))
' %%%%%% Show the resident's name and whether they have a room. %%%%%%
Dim dbroom As New pbu_housingEntities
Dim queryStudent = From p In dbroom.Residents _
Where p.people_code_id = people_code_id _
Join b In dbroom.Buildings On p.building Equals b.id _
Join r In dbroom.Rooms On p.room Equals r.id
Select p, b, r
lblName.Text = CStr(Session("name"))
If queryStudent.Count.Equals(0) Then
lblRegistered.Text = "We do not have you currently registered for campus housing."
Else
lblRegistered.Text = "You are currently registered for " & queryStudent.First.b.building_name & " " & queryStudent.First.r.room1 & "."
End If
' Initiate variables to check for class settings.
Dim dbConfig As New pbu_housingEntities
Dim whatdatest = From p In dbConfig.Configs
Dim whatdatee = From p In dbConfig.Configs
' Add in a check for contract signatures.
Dim dbContracts As New pbu_housingEntities
Dim clcexists = From p In dbContracts.Signatures _
Where p.StudentID = people_code_id _
And p.ContractType = "clc" _
Order By p.ID Descending _
Select p
Dim rhcexists = From p In dbContracts.Signatures _
Where p.StudentID = people_code_id _
And p.ContractType = "rhc" _
Order By p.ID Descending _
Select p
' Shows or hides the buttons for contracts based on whether signatures exist.
Dim clcfirst = clcexists.FirstOrDefault()
Dim rhcfirst = rhcexists.FirstOrDefault()
If clcfirst Is Nothing Then
pnlSignCLC.Visible = True
Else
pnlSignCLC.Visible = False
End If
If rhcfirst Is Nothing Then
pnlSignRHC.Visible = True
Else
pnlSignRHC.Visible = False
End If
' Determine if the student is eligible to register for class.
Dim classes() As String = {"FR%", "SO", "JR", "SR", "SR5"}
Dim flag As String = "N"
For Each value As String In classes
' Pull in the dates the student should be able to register for this class, compare them to the current date.
Dim current_value = value
If class_level = current_value Then
flag = "Y"
Response.Write("hello")
whatdatest = From p In dbConfig.Configs _
Where p.Description = current_value + "OD" _
Select p
whatdatee = From p In dbConfig.Configs _
Where p.Description = current_value + "CD" _
Select p
' If the current date is within their registration period...
If Date.Now >= whatdatest.First.dateValue And Date.Now <= whatdatee.First.dateValue Then
Dim person_name As String = CStr(Session("person_name")) ' Must stay here or will conflict.
Dim hasroom = From p In dbConfig.Residents _
Where p.person_name = person_name _
Where p.semester = term _
Where p.year = year _
Select p
' If they have signed their contracts, lets let them register for a room.
If hasroom.Count.Equals(0) AndAlso clcfirst IsNot Nothing AndAlso rhcfirst IsNot Nothing Then
pnlBegin.Visible = True
btnBegin.Enabled = True
' If they are already registered for a room, let them delete their reservation.
ElseIf clcfirst IsNot Nothing AndAlso rhcfirst IsNot Nothing Then
pnlDelete.Visible = True
btnDelete.Enabled = True
Else
' In any other situation, we don't need to do anything.
' There really shouldn't be any other situation.
End If
' What to do if the current date is not within the room reservation window.
Exit For
Else
Dim class_name As String
Select Case current_value
Case "FR%"
class_name = "Freshman"
Case "SO"
class_name = "Sophmore"
Case "JR"
class_name = "Junior"
Case "SR"
class_name = "Senior"
Case "SR5"
class_name = "Fifth year Senior"
End Select
lblError.Text = "You are currently a " & current_value & ". You will be eligible to reserve a room between" _
& whatdatest.First.dateValue & " and " & whatdatee.First.dateValue & ". Please come back during those dates. Thanks!"
End If
Exit For
Else
End If
Next
If flag = "N" Then
' What to do if the user isn't assigned a class level at all!
lblError.Text = "Oops...Something might be wrong with our records. We don't have you registered for classes. Please contact Dave Mackey, x4543."
End If
【问题讨论】：
-
您是否调试并单步执行了代码以查看它在做什么？
-
你有很多其他的。你能告诉我们是哪一个问题吗？
-
由于 Exit For 位于 Date 内，因此请检查日期条件不得为真...
-
它曾经 Response.Write("hello") 吗？如果不是，那么 class_level = current_value 在任何时候都不相同。
-
会不会出现错误。是否在 Debug\Exceptions 中检查了 Common Language Runtime Exceptions Throw... 如果没有，请检查并再次运行以查看是否确实存在异常。