I'm working on a Sindows Forms application to help keep inventory of some scanners. I'm using Linq2Sql, each table has an id column. On my repair history form. I'm trying to use the serial number from the inventory table so it goes to the database and looks up the sID from the table and it returns the correct value, but when I go to send all the entered data to the history table it gets a null reference exception.
Dim db As New DataClasses1DataContext
Dim rep As Scanner_Repair_History
Dim scan = (From Scanner_Inventory In db.Scanner_Inventories Where scannerid.Text = Scanner_Inventory.SN Select Scanner_Inventory.SID).FirstOrDefault
rep.SID = scan
rep.Date_Broken = datebroke.Value
rep.Description = description.Text
rep.Send_Date = senddate.Text
rep.Recieve_Date = recievedate.Text
rep.Cost = cost.Text
rep.PlantID = plantid.Text
rep.BID = brokenid.Text
rep.RMAnumber = rmanum.Text
db.Scanner_Repair_Histories.InsertOnSubmit(rep)
db.SubmitChanges()
is that me but you didn't instanciate your "rep" variable
You don't have a defined object for placement with a 'new' keyword but I am also curious if it is a system.type.
Update based on Jinx88909
You may be returning an entire POCO Object that may be null and have a null property. You can adjust this most times by doing a null condition if you are using .NET 4.5 and up. '?.' operator.
Dim db As New DataClasses1DataContext
'I need to be a new object and not instantiated as Nothing
Dim rep As New Scanner_Repair_History
'You have the potential for a nothing value here as 'FirstOrDefault' includes a potential Nothing'.
'I would get the entire object and then just a property of it after the fact
Dim scan = (From Scanner_Inventory In db.Scanner_Inventories Where scannerid?.Text = Scanner_Inventory?.SN Select Scanner_Inventory).FirstOrDefault?.Sid
If scan IsNot Nothing Then
rep.SID = scan 'Could you maybe want scan.Id or something similar?
rep.Date_Broken = datebroke.Value
rep.Description = description.Text
rep.Send_Date = senddate.Text
rep.Recieve_Date = recievedate.Text
rep.Cost = cost.Text
rep.PlantID = plantid.Text
rep.BID = brokenid.Text
rep.RMAnumber = rmanum.Text
db.Scanner_Repair_Histories.InsertOnSubmit(rep)
db.SubmitChanges()
Else
Console.WriteLine("I got nothing for you with the inputs you put in!")
End If
Related
I have a list of records and for Employee R1005, I need to check if that Employee has been Enabled for login alert (i.e EnableLoginAlert = Yes), then a button will be displayed.
CompanyID EmployeeNo EnableLoginAlert
10046 R1005 Yes
20041 Ajax12 No
47021 Drek Yes
I have tried the below codes:
If dCompanyDetails.Tables(0).Rows.Count > 0 Then
Dim dataView As DataView = dCompanyDetails.Tables(0).DefaultView
dataView.RowFilter = "EmployeeNo = '" & strEmployeeNumber & "'"
Dim svalue As String = dataView.Table.Rows(0).ItemArray(0).ToString()
If svalue = "No" Then
AlertButton.Visible = False
ElseIf svalue = "Yes" Then
{
//Do something else
}
End If
End If
If you are going to use a DataView then use it. This:
Dim svalue As String = dataView.Table.Rows(0).ItemArray(0).ToString()
is simply going back to the DataTable and using it, ignoring the DataView. The DataView contains DataRowView objects so get the one you need and use it. It is similar to a DataRow and you can use it the same way in this case:
Dim enableLoginAlert = CStr(dataView(0)("EnableLoginAlert")) = "Yes"
Now you have an actual Boolean that represents the state you want.
That's not how you should do it though. Generally speaking, you would use a DataView when you want to bind data. In fact, if you bind a DataTable then the data you see in the UI actually comes from the DefaultView. That's why you can filter and sort it. In this case, there are better options.
If you want to find a row by its primary key then the Rows collection of a DataTable has a Find method, e.g.
Dim row = dCompanyDetails.Tables(0).Rows.Find(strEmployeeNumber)
Dim enableLoginAlert = CStr(row("EnableLoginAlert")) = "Yes"
If you're searching by other than the primary key, the DataTable itself has a Select method. Because multiple rows may match, it returns an array, so you need to get the row out of that, e.g.
Dim row = dCompanyDetails.Tables(0).Select($"EmployeeNo = '{strEmployeeNumber}'").First()
Dim enableLoginAlert = CStr(row("EnableLoginAlert")) = "Yes"
If you want to look up a single row it's perhaps easiest to use LINQ:
Dim row = dCompanyDetails.Tables(0).Rows.Cast(Of DataRow).AsQueryable().FirstOrDefault(Function(r) r("EmployeeNo").ToString() = strEmployeeNumber)
If row IsNot Nothing AndAlso row("EnableLoginAlert").ToString() = "Yes" Then
...
..though I'd be the first to claim that using LINQ on base DataTables is very verbose, because of the Cast/AsQueryable. I'd use strongly typed DataTables (in a dataset); if you were to convert your code to using strongly typed tables it would look like:
Dim r = someDataSet.AProperTableName.FirstOrDefault(Function(r) r.EmployeeNo = strEmployeeNumber)
If r?.EnableLoginALert = "Yes" Then
...
...using strongly typed datatables is much less messy..
nb: You need to Imports System.Linq for these to work
That LINQ is the same thing as:
For Each r as DataRow in dCompanyDetails.Tables(0)
If r("EmployeeNo").ToString() = "R1005" AndAlso r("EnableLoginAlert").ToString() = "Yes" Then
...
You also have the option of using DataTable.Select (not a LINQ thing, though LINQ has a Select too)
Dim matchingRows = dCompanyDetails.Tables(0).Select($"[EmployeeNo] = '{strEmployeeNumber}'")
If matchingrows.Count > 0 AndAlso matchingRows(0)("EnableLoginAlert").ToString() = "Yes"
I'm a bit stuck trying to work something into my code.
What I'm looking to do is to work out whether someone is a member of any one of a collection of groups. I'm not worried about which group specifically, I only want to know:
"Is user "X" a member of at least one of this collection of groups?"
The good news is, ALL these group names start in the same way:
Google-FullAccess
Google-RestrictedAccess
Google-MailOnly
Google-Enterprise etc.
Here's what I'm using to check for a specific group:
Dim ctx As DirectoryServices.AccountManagement.PrincipalContext = New DirectoryServices.AccountManagement.PrincipalContext(DirectoryServices.AccountManagement.ContextType.Domain, "net.mydomain.co.uk")
Dim user As DirectoryServices.AccountManagement.UserPrincipal = DirectoryServices.AccountManagement.UserPrincipal.FindByIdentity(ctx, tbxuserID.Text)
Dim googleFull As DirectoryServices.AccountManagement.GroupPrincipal = DirectoryServices.AccountManagement.GroupPrincipal.FindByIdentity(ctx, "Google-FullAccess")
If user.IsMemberOf(googleFull) Then
GoogleAccess = 1
GoTo Proceed
End If
I then repeat this block of code to check for the next group and so on.
Is there a way I can adapt this to check for any group starting with "Google-"? Here's what I'd like to do but obviously doesn't work:
Dim googleCheck As DirectoryServices.AccountManagement.GroupPrincipal = DirectoryServices.AccountManagement.GroupPrincipal.FindByIdentity(ctx, "Google-*")
Help much appreciated!
I found the solution! The following works for me (after working out and storing the DistinguishedName in a String variable from a previous query - I also declare GoogleCheck as a Boolean variable beforehand):
Dim rootEntry As DirectoryServices.DirectoryEntry = New DirectoryServices.DirectoryEntry("LDAP://DC=net,DC=mydomain,DC=co,DC=uk")
Dim srch As DirectoryServices.DirectorySearcher = New DirectoryServices.DirectorySearcher(rootEntry)
srch.SearchScope = DirectoryServices.SearchScope.Subtree
srch.Filter = "(&(CN=Google-*)(objectCategory=group)(member=" + DistinguishedName + "))"
Dim res = srch.FindOne()
If res IsNot Nothing Then
GoogleCheck = True
Else
GoogleCheck = False
End If
The program is a booking system (amongst other things) for a holiday letting company. I am working on the screen where you can see properties and ammend them or add more (etc)
Okay so It works fine in my other cases, but this one it just doesn't want to accept...I expect it's something stupid. Basically In the initial loading of the entire program I filled the Data Tables with the relevant info and then accessed them when needs be, in this case I am in the Form Properties and want to access Bookings (Which were made in FrmBookings) to see when the property is next booked to have guests in.
Dim Intcounter As Integer = 0
Dim NumberBookingRecords As Integer = BookingsNumRecs
Dim PropertyName As String
Dim PropertyFromBookings As String
Do
PropertyName = DTProperties(Intcounter)("Property Name").ToString
PropertyFromBookings = (DTBookings(NumberBookingRecords)("Property").ToString)
If PropertyName = PropertyFromBookings Then
lblDateOfArrival.Text = (DTBookings(NumberBookingRecords)("Arrival").ToString)
Intcounter = Intcounter + 1
Else
If Not NumberBookingRecords = 0 Then
NumberBookingRecords = NumberBookingRecords - 1
Else
End If
End If
Loop Until Intcounter >= intNumPropertyRecs
However when I get to PropertyFromBookings = (DTBookings(NumberBookingRecords)("Property").ToString)
it tells me that it could not be set to an instance of an object...no matter what I try an access from DTBookings I get the same response.
This is in the initial load form at the opening of the program
Dim FSBookings As New FileStream(strFileNameBookings, FileMode.OpenOrCreate, FileAccess.Read)
Application.DoEvents()
If FileLen(strFileNameBookings) > 0 Then
DTBookings.ReadXmlSchema(strFileNameBookings)
DTBookings.ReadXml(strFileNameBookings)
BookingsNumRecs = DTBookings.Rows.Count
intCurrRec = 1
Else
End If
FSBookings.Close()
blnStopAuto = True
blnStopAuto = False
Based on your code sample, DTBookings() is a function call. There are two possibilties here. Either:
The result of that function is Nothing, and when you try to use a Nothing as if there were an actual object there, (in this case, when trying to look up the ("Property") indexer) you'll get that exception, or ...
The result of the ("Property") index returns Nothing, in which case you'll get that exception when you try to call the .ToString() method.
I am trying to make an array of hashtables. I don't know if this is the best solution, in PHP I would just do a multi-dim array, but it's not so easy in .NET. I am pretty new o VB, so if there is a better solution for this please explain.
I have 2 emails fields for a contact, and a contact can have many. I just want to load in the first two on the edit page for editing, whatever they may be.
Private Sub loadPrimaryContactEmails(ByVal db As CRMDataDataContext, ByVal contactID As Guid)
Dim q = (From ce In db.ContactEmails Where ce.ContactID = contactID Select ce).Take(2)
Dim Emails As Array
Dim count = 0
For Each email In q
Emails(count) = New Hashtable
Emails(count).Add("email", email.Email)
Emails(count).Add("label", email.Label)
Emails(count).Add("id", email.ContactEmailID)
count = count + 1
Next
txtPCEmail1.Text = Emails(0).Item("email")
txtPCEmail1Label.Text = Emails(0).Item("label")
lblEmail1ID.Text = Emails(0).Item("id")
txtPCEmail2.Text = Emails(1).Item("email")
txtPCEmail2Label.Text = Emails(1).Item("label")
lblEmail2ID.Text = Emails(1).Item("id")
End Sub
I get the error the first time I try to reference my array:
txtPCEmail1.Text = Emails(0).Item("email")
The error is:
Object variable or With block variable not set.
It builds, so I thought it might work. I can't just loop through my datasource because I have to explicitly set textbox fields. Is there a better way to go about doing this? Or is there a way to make an array of hashtables work?
EDIT - here is the good code:
So I went w/ the HybridDictionary...
Private Sub loadPrimaryContactEmails(ByVal db As CRMDataDataContext, ByVal contactID As Guid)
Dim q = (From ce In db.ContactEmails Where ce.ContactID = contactID Select ce).Take(2)
Dim Emails As New HybridDictionary()
Dim count = 1
For Each email In q
Emails.Add("email" + NCStr(count), email.Email)
Emails.Add("label" + NCStr(count), email.Label)
Emails.Add("id" + NCStr(count), email.ContactEmailID)
count = count + 1
Next
txtPCEmail1.Text = Emails("email1")
txtPCEmail1Label.Text = Emails("label1")
lblEmail1ID.Text = Emails("id1")
txtPCEmail2.Text = Emails("email2")
txtPCEmail2Label.Text = Emails("label2")
lblEmail2ID.Text = Emails("id2")
End Sub
SO yeah, kind of a hack, but I don't feel like I should have to making special methods just to load some data into a dictionary or array or whatever.
Arrays in VB.NET are different than in PHP. You will need to define the size of your array before attempting to set elements of the array.
Better yet, consider using the generic List<T> collection.
Yes Phil is right you haven't specified the Initial Size of the Array.
And as suggested by him Use generic list or I would recommend
"System.Collections.Specialized.StringCollection" Class or "System.Collections.Specialized.HybridDictionary" class
Build the hashtable first and then build the array.
Dim hash As New Hashtable()
hash.Add("Header", shortModel)
hash.Add("SpecInfo", specinfo)
hash.Add("SerialNumber", serie & "-L")
hash.Add("SerialNumber2", serie)
hash.Add("seriel", serie & "-L")
hash.Add("serie", serie)
hash.Add("Product", modelBase)
hash.Add("varBC", bc)
hash.Add("box_id", boxId.Substring(4).ToString)
Dim dt As DataTable = DbUtil.GetCursor("SFISM4.PKG_AGENCY.sp_get_print_param", {New OracleParameter("in_serie", "3CE5151ZW4")})
For Each row As DataRow In dt.Rows
hash.Add(row("NAME"), row("VALUE"))
Next
Dim mArray(hash.Count() - 1, 1) As String
Dim i As Integer = 0
For Each row As DictionaryEntry In hash
mArray(i, 0) = row.Key.ToString()
mArray(i, 1) = row.Value.ToString()
i = i + 1
Next
I have two LINQ objects which have exactly the same columns and I would like to be able to update one with the fields from the other. I first create a new object from some data in a file, then I query the database for an existing item with the same ID. What I would like to be able to do is update the existing objects details with the newly created objects details.
So far the way I have been doing it is to list all the columns and update them manually but as you can see this can cause maintenance headaches.
With OldCaller
.ADDRESS = NewCaller.ADDRESS
.COMPANY = NewCaller.COMPANY
.CONTACT_HOURS = NewCaller.CONTACT_HOURS
.CONTACT_NAME = NewCaller.CONTACT_NAME
.CUSTOMER_ID = NewCaller.CUSTOMER_ID
.EMAIL_ADDRESS = NewCaller.EMAIL_ADDRESS
.FAX_NUMBER = NewCaller.FAX_NUMBER
.FAX_TYPE = NewCaller.FAX_TYPE
.MOBILE = NewCaller.MOBILE
.POSTCODE = NewCaller.POSTCODE
.PUBLIC_ADDRESS = NewCaller.PUBLIC_ADDRESS
.PUBLIC_TELEPHONE = NewCaller.PUBLIC_TELEPHONE
.STATE = NewCaller.STATE
.SUBURB = NewCaller.SUBURB
.TELEPHONE = NewCaller.TELEPHONE
End With
I would like to be able to find a way to clean this up a bit. Does anyone know of a better way to do what I need.
I do this sort of thing when I create an instance of an object from a template. Basically I have a method that iterates over the public properties of the template, finds the corresponding property in the object being created, and invokes the property setter on the new object, all via reflection.
I haven't tested this yet but this is what I have come up with.
Dim _OldCallerProperties = OldCaller.GetType().GetProperties(Reflection.BindingFlags.Public)
Dim _NewCallerProperties = NewCaller.GetType.GetProperties(Reflection.BindingFlags.Public)
For Each Prop In _OldCallerProperties
Dim _matchingProperty = _NewCallerProperties.Where(Function(p) p.Name = Prop.Name).FirstOrDefault
Dim _newvalue = _matchingProperty.GetValue(_matchingProperty, Nothing)
Prop.SetValue(Prop, _newvalue, Nothing)
Next
Like I said I haven't tested it but I'm sure it should work.