I have the following query:
Dim queryStudent = (From p In dbContext.Residents _
Where p.people_code_id = people_id _
Where p.year = year _
Where p.semester = semester _
Join b In dbContext.Buildings On p.building Equals b.id _
Join r In dbContext.Rooms On p.room Equals r.id
Select p, b, r)
I then attempt to pull the building and room for that individual like so:
room = queryStudent.FirstOrDefault.r.id
building = queryStudent.FirstOrDefault.b.id
But I receive an Object reference not set to an instance of an object error.
I tried doing something like
If IsNothing(queryStudent.FirstOrDefault.r.id) Then
room = ""
Else
room = queryStudent.FirstOrDefault.r.id
End If
But that still generates the same error.
Check if r is nothing instead of the id of r.
If IsNothing(queryStudent.FirstOrDefault.r) Then
room = ""
Else
room = queryStudent.FirstOrDefault.r.id
End If
I suspect queryStudent.FirstOrDefault is null. If you try to access a property of a null object, you get that exception. Try this approach:
If IsNothing(queryStudent.FirstOrDefault) Then
room = ""
Else If IsNothing(queryStudent.First.r) Then
room = ""
Else
room = queryStudent.FirstOrDefault.r.id
End If
In each case, you are checking that the object you are about to access is not null.
Related
I get the error
Procedure or function has to many arguments specified
but only sometimes. It's a REST API and cellphones call this function to validate the user. Today it's onli 1-2 cellphones and they make the call every second minute.
It works well most times but sometimes I get this error code.
To see what's wrong, I've made a small loop that gathers the parameters into a string. And sometimes they are two #GUID and #Datum and sometimes repeat themselves.
Here is the VB code:
Public Shared Sub validatePhone(secretKey As String, ByRef _RS As phoneData, Fnr As Integer)
Dim connStr As String = System.Configuration.ConfigurationManager.AppSettings("ConnStringSQL")
Dim Conn As SqlConnection = New System.Data.SqlClient.SqlConnection(connStr)
Dim _theString As New System.Text.StringBuilder
Try
_RS.message = ""
_RS.status = True
Dim Status As Integer = 0
Dim _GUID As Guid = New Guid(secretKey)
Try
Conn.Open()
Catch ex As Exception
End Try
cmd.Connection = Conn
Apt.SelectCommand = cmd
cmd.CommandType = CommandType.StoredProcedure
cmd.CommandText = "API2017_checkPhone"
cmd.Parameters.Clear()
cmd.Parameters.Add("#GUID", SqlDbType.UniqueIdentifier).Value = _GUID
cmd.Parameters.Add("#Datum", SqlDbType.SmallDateTime).Value = Now
For Each item As SqlParameter In cmd.Parameters
_theString.Append(item.ParameterName & ";")
Next
Apt.Fill(ds, "DataCheckPhone")
If ds.Tables("DataCheckPhone").Rows.Count > 0 Then
With ds.Tables("DataCheckPhone").Rows(0)
Status = .Item("spStatus")
If Status = 0 Then
_RS.Namn = .Item("Namn")
_RS.SalesID = .Item("SalesID")
_RS.Anlaggning = .Item("Anlaggning")
_RS.Anlnr = .Item("Anlnr")
Funktions.URLEncodeStr(_RS.Namn)
Funktions.URLEncodeStr(_RS.Anlaggning)
End If
End With
Else
Dim _Lnum As Integer
Funktions.Logg(Fnr & ": " & "Fatal error", 999, _Lnum, 0)
_RS.message = "Error 999:" & _Lnum.ToString
Return
End If
Catch ex As Exception
_RS.status = False
_RS.Anlaggning = Nothing
_RS.Anlnr = 0
_RS.Namn = Nothing
_RS.SalesID = Nothing
Dim _Lnum As Integer
Funktions.Logg(Fnr & ": " & ex.Message & "{" & _theString.ToString & "}", 999, _Lnum, 0)
_RS.message = "Error 999:" & _Lnum.ToString
Finally
ds.Tables.Clear()
Try
ds.Tables("DataCheckPhone").Dispose()
Catch ex As Exception
End Try
End Try
Try
Conn.Close()
Conn.Dispose()
Catch ex As Exception
End Try
End Sub
And here is the stored procedure:
ALTER PROCEDURE [dbo].[API2017_checkPhone]
#GUID as uniqueidentifier,
#Datum as smalldatetime
AS
DECLARE #Status AS INT
DECLARE #Anlaggning AS NVARCHAR(50)
DECLARE #Namn AS NVARCHAR(50)
DECLARE #Anlnr AS INT
DECLARE #SalesID AS uniqueidentifier
DECLARE #LockedSalesman AS BIT
DECLARE #LockedAnlaggning AS BIT
SET #Status = 0
IF EXISTS (SELECT * FROM KK2017_connectedPhones WHERE [guid] = #guid)
BEGIN
SET #status = 0
SET #salesID = (SELECT salesID FROM KK2017_connectedPhones
WHERE [guid] = #guid)
SET #Anlnr = (SELECT anlnr FROM KK2017_Säljare WHERE salesID = #salesID)
SET #Namn = (SELECT Namn FROM KK2017_Säljare WHERE salesID = #salesID)
SET #Anlaggning = (SELECT namn FROM KK2017_Anlaggning WHERE anlnr = #Anlnr)
SET #LockedSalesman = (SELECT locked FROM KK2017_Säljare WHERE salesID = #salesID)
UPDATE KK2017_Säljare
SET inloggad = #Datum
WHERE salesID = #SalesID
IF #LockedSalesman = 1
BEGIN
SET #Status = 2
END
SET #LockedAnlaggning = (SELECT locked FROM KK2017_Anlaggning
WHERE AnlNr = #Anlnr)
IF #LockedAnlaggning = 1
BEGIN
SET #status = 3
END
END
ELSE
SET #status = 1
SELECT
#Status AS spStatus,
#Anlaggning AS Anlaggning,
#anlnr AS anlnr,
#Namn AS namn,
#SalesID AS salesID
I must have done something wrong but can not see it.
If anyone has a proposal, I would be grateful.
/Claes
You have a threading issue because you have defined cmd as shared, which means there is only one instance servicing all of the incoming requests. Sometimes two threads are in the process of adding parameters at the same time, and both threads end up with four, hence the error.
The standard pattern here would be declare cmd as a local variable, and instantiate a new instance each time the function is called. The overhead to this is negligible.
Also, avoid shared variables in multithreaded applications (such as web services). There is only one copy of the variable for all users and all threads, and 99% of the time that is not what you actually want. For the other 1% usually you'd use application variables or HttpCache. In this case you should use a local variable.
I have a recursive function that creates a list of items based on their hierarchy(integer is used to determine which level 1 to 10 max). There can be x number of items in any given level. I want to store all the items that belong the same level at the corresponding index of the jagged array. The items aren't retrieved based on their level so the level can be jumping around all of over the place as the function recurses.
Function RecurseParts(lngPartID1, lngLevel) As Object
'this function will recursivley print the parts lists for the part ID passed in
If IsNumeric(lngPartID1 & "") Then
Dim objRSTemp As Object = Server.CreateObject("ADODB.Recordset")
objRSTemp.CursorLocation = adUseClient
objRSTemp.Open(PART_LIST_SQL & lngPartID1, objConn, adOpenForwardOnly, adLockReadOnly)
'objRSTemp.ActiveConnection = Nothing
If objRSTemp.eof And objRSTemp.bof Then
'PROBLEM, WE HAVE NO RECORDS
Response.Write("There Were No Parts For This Assembly (Part ID #:" & lngPartID1 & ")")
Else
'make output
Dim strTemp As String = String.Empty
If lngLevel <> 1 Then strTemp = " style=""display: none;"">"
Response.Write("<table id='tblparts" & lngCurrentLineNum & "' border=""0"" cellspacing=""0"" width=""100%"" cellpadding=""1"" " & strTemp)
Do Until objRSTemp.EOF
'increase the current line num
lngCurrentLineNum = lngCurrentLineNum + 1
'get current Part ID
lngCurrentPartID = objRSTemp("PartID").value
'reset flag
blnIsAssm = False
'loop thru array of assemblies to see if this is a parent
For ctr = 0 To UBound(arrAssmList, 2)
If arrAssmList(0, ctr) = lngCurrentPartID Then
'the current part is an assembly
blnIsAssm = True
Exit For
ElseIf arrAssmList(0, ctr) > lngCurrentPartID Then
Exit For
End If
Next
If blnIsAssm Then
'recurse these parts
If RecurseParts(objRSTemp("PartID").value, lngLevel + 1) = True Then
'awesome
End If
End If
objRSTemp.MoveNext()
Loop
Response.Write("</table>")
End If
If objRSTemp.State Then objRSTemp.Close()
objRSTemp = Nothing
'RETURN FUNCTION
RecurseParts = True
Else
'no PART ID passed in
Response.Write("No Part ID Passed In")
RecurseParts = False
End If
End Function
It sounds like a Dictionary would work here.
Dim myDict As New Dictionary(Of Integer, List(Of String))
In your recursive function. The parts in the {} are the parts you have to supply.
'this builds the keys as you go
If Not myDict.ContainsKey({{key} -> your Integer}) Then
'add key and use the From statement to add a value if know at this time
myDict.Add({key}, New List(Of String) From {value})
Else
myDict({key}).Add({string to insert at this level})
End If
List of keys in reverse order:
Dim keys = myDict.Keys.OrderByDescending(Function(k) k)
I was able to create a List to store all the partIDs and their levels.
Dim arrSubID As New List(Of List(Of Integer))()
Function RecurseParts(paramenters)
For ctr = 0 To UBound(arrAssmList, 2)
If arrAssmList(0, ctr) = lngCurrentPartID Then
'checks whether we need a new index in the list
If lngLevel + 1 > arrSubID.Count Then
arrSubID.Add(New List(Of Integer))
End If
'adds the partID where it belongs!
arrSubID(lngLevel).Add(lngCurrentPartID)
blnIsAssm = True
Exit For
ElseIf arrAssmList(0, ctr) > lngCurrentPartID Then
Exit For
End If
Next
End Function
I am using the following query to pull a row from a datatable in memory.
Dim results = _
From myRow In exceldt.AsEnumerable() _
Where myRow.Field(Of String)("Serial Number") = Row.Item("Serial Number") _
Select myRow
resultrow = results.CopyToDataTable.Rows(0)
I need to get the index of the resultrow when it was part of exceldt. I can't seem to find anything on this. Suggestions?
I don't work in VB.net so forgive my code but you can get the index of a projection with something along the lines of this:
Dim result = exceldt.AsEnumerable() .Select (Function(item, index) _
New With { .Index = index, .SerialNumber = item }).ToList
I can't provide much more with in VB but this quick example does work as a Console app. You can see how the select / projection captures the index and item. You will need to incorporate similar logic before filtering (where) you initial enumeration.
Dim names = {"Andy", "Tom", "Fred", "Sally"}
Dim results = names _
.Select(Function(item, index) New With {.Index = index, .Name = item}) _
.OrderBy(Function(item) item.Name)
For Each item In results
Console.WriteLine("{0} - {1}", item.Index, item.Name)
Next
results
0 - Andy
2 - Fred
3 - Sally
1 - Tom
This should do the trick
int index = exceldt.Rows.IndexOf(results);
I have some existing code that I need to modify to search more than one keyword. (I am new to all this by the way)
Dim topics As IQueryable(Of Global.Platform.Core.Data.Topic) = _
From t In _db.Topics
Where t.IsActive = True And t.TopicTitle.Contains(criteria) And t.ForumID = 0 And Not t.TopicTitle.Contains("default") And t.Member.IsActive = True And t.IsActive = True
Order By t.DateCreated Descending
Select t
Take (take_x)
Return topics
How would i go about changing this so if I entered criteria "cat hair" it would do an OR search. so ...t.TopicTitle.Contains("cat") OR t.TopicTitle.Contains("hair") ....
Of course it would need to be dynamic.
I tried this but could not get it to work.
Dim criteriaArr As Array = criteria.Split(" ")
Dim new_criteria As String = " t.TopicTitle.Contains(" + criteriaArr(0) + ")"
If criteriaArr.Length > 1 Then
For Each item As String In criteriaArr
new_criteria += " Or t.TopicTitle.Contains(" + item + ")"
Next
End If
The idea was to split the spaces and keep appending to the where clause. I know in SQL this might have worked, but how would I go about in this scenario?
You can use a combination of .Any and .Contains:
var strings = new List<string> { "cat", "dog", "bill" };
using (var context = new MyEntities())
{
var matches = context.MyObject.Where(x => strings.Any(s => x.TopicTitle.Contains(s)));
}
VB:
Dim strings = {"cat", "dog", "bill"}
Using context = New MyEntities()
Dim matches = context.MyObject.Where(Function(x) strings.Any(Function(s) x.TopicTitle.Contains(s)))
End Using
This is taking the strings list of query words, and checking to see if there are any of them that the TopicTitle contains.
Sorry, that's in C#, but you can see how to do the lamda expression in the .Where. Just send in a List to your method that does the query, and you're good to go.
Assuming TopicTitle and the criteria are space delimited strings I would intersect the two collections and check if there were any matches.
Dim topics As IQueryable(Of Global.Platform.Core.Data.Topic) = _
From t In _db.Topics
Where t.IsActive = True And t.TopicTitle.Intersect(criteria).Any()
And t.ForumID = 0 And Not t.TopicTitle.Contains("default")
And t.Member.IsActive = True And t.IsActive = True
Order By t.DateCreated Descending
Select t
Take (take_x)
Return topics
I have a GridView which is showing results and from which I am deleting a result using the auto-created delete link. My code behind to remove the row and associated info. is:
Private Sub GridView1_RowDeleting(sender As Object, e As System.Web.UI.WebControls.GridViewDeleteEventArgs) Handles GridView1.RowDeleting
' The deletion of the individual row is automatically handled by the GridView.
Dim dbDelete As New pbu_housingEntities
' Remove individual from the bed.
Dim remove_bed = From p In dbDelete.Beds _
Where p.occupant = GridView1.SelectedRow.Cells(3).Text _
Where p.room = GridView1.SelectedRow.Cells(6).Text _
Where p.building = GridView1.SelectedRow.Cells(5).Text _
Order By p.id Descending _
Select p
remove_bed.First.occupant = ""
dbDelete.SaveChanges()
' Increase number of open spaces in room.
Dim update_occupancy = From p In dbDelete.Rooms _
Where p.room1 = GridView1.SelectedRow.Cells(6).Text
Where p.building = GridView1.SelectedRow.Cells(5).Text _
Select p
update_occupancy.First.current_occupancy = update_occupancy.First.current_occupancy - 1
dbDelete.SaveChanges()
End Sub
It seems that it is not able to grab the row that is being deleted, so it is always giving me a "Object reference not set to an instance of an object" error.
Use GridView1.Rows(e.RowIndex).Cells(.......