Check If XML Node Is Empty/Null/Blank?
Apr 8, 2010
The code below works fine as long as there are values within an XML node (For example the <CPU>Intel</CPU> node below) but it throws an Exception error when the node value is blank/null whatever as in the example node <Monitor> </Monitor>.t's ok if the node value is blank, I just want to check for it and not throw an exception error.This question uses the following XML snippet below: Note: The tag <Monitor></Monitor> has no value in it.
<PCSettings>
<SystemSettings>
<CPU>Intel</CPU>
[code].....
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Jun 17, 2009
I am getting product id value some times null and empty from databasehere how i check if valule null and empty
productid = IIf(IsDBNull(TempDT.Rows(0).Item("productid")) =
True,
"", TempDT.Rows(0).Item("productid"))
[code].....
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Apr 7, 2012
I have some application settings that I want to put some error checking in and the below code does not work.
If My.Settings.SmtpServer = ("") Then
MsgBox("SMTP cannot be blank!", vbExclamation, "SMTP App")
End If
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Feb 29, 2012
I have the following code that checks if the value in a cell contains a nummeric value.
Private Sub dgvOrderRegel_CellValidating(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellValidatingEventArgs) Handles dgvOrderRegel.CellValidating
Select Case e.ColumnIndex
Case 4 'Aantal
If Not IsNumeric(e.FormattedValue) Then
[Code]...
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Jul 28, 2009
I'm using FileHelper to generate object's property. Here is an example of one property:
<FieldOptional(), _
FieldTrim(TrimMode.Both)> _
<FieldNullValue(GetType(String), " ")> _
Public StoreNo As String
As you can see the StoreNo will either have a value or " ", one of the business policy is to check if the StoreNo is empty or nothing if the object's StoreNo is empty or null then the record will not create.
I though about creating an HasValue Function in the class to check the StoreNo and other properties in the object but I feel like it is a hack.
Public Function HasValue() As Boolean
Dim _HasValue As Boolean = True
If StringHelper.IsNullOrBlank(Me.StoreNo) Then
[Code]....
I don't think this approach is an ideal solution. what if the StoreNo is remove or change to something else. What's the best approach to check object's property?
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Nov 8, 2009
i need to check all child node when the parent node is checked and i had do research from the internet but it seem that i had a error which is Type 'MSComctlLib.Node' is not defined.do i need to import any reference? [code]
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Nov 20, 2011
I think we can just draw an image that resemble the grid using this article : drawing in a datagridview Currently creating a way to make the image drawn in tile mode. Each time I develop a datacentric application using VB.NET regardless of how much the data displayed in the datagrid, I always want the grid to display full row of empty data, not just blank panel. Can we achieve this using VB.NET design time property? And also, we must not trigger the display of vertical scrollbar this way..
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Jan 22, 2009
May I define an empty node in a XML file then do something?
Dim ReasonNodeList As Xml.XmlNodeList = SomeNode.SelectNodes("./REASON_CODE/REASON")
Dim CReasonNode As Xml.XmlNode = ReasonNodeList(ReasonNodeList.Count - 1)
But maybe this node doesn't exist, I am not sure is there any error occurring during the running.Except the error of length of NodeList.
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Jun 11, 2009
i have a combobox which get value from database through dataset. when i run the program n click on the combobox, the value is auto fill in with data from database. is there anyway to add a blank entries to the selection on the combobox??
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Mar 10, 2011
the input box cannot grab the NULL value (blank).
i'm try make try and catch. let's see my code..
Private Sub GetData()
Dim row As Integer = DataGridView1.Rows.Count
Dim N As Integer
[Code].....
Error:Value of type 'System.DBNull' cannot be converted to 'Integer'. can you show me a "hack" to use null / blank ? to read it and catch the err0r ?
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Mar 8, 2012
'Attributes
For Each attRefID As ObjectId In myBRef.AttributeCollection
Dim myAttRef As AttributeReference = attRefID.GetObject(OpenMode.ForRead)
[Code].....
How do I tell if my Enumerator property hasn't been given a value?
How do I tell if it is blank?
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Jun 28, 2010
This must've have been asked before but I couldn't locate it. In a mixed code project (VB and C#) we were debugging some old Visual Basic code where a statement as follows could be found:
If Request.Params("xxx") <> "" Then
'do something
I considered this a bug as Request.Params could be null, in which case the statement would've become false which wasn't the idea. So I thought. I just found out, -- probably for the tenth time and I will keep forgetting -- that the following two statements are not equal, while Nothing in VB should be equal to null in C# (thought I):
if(String.Empty == null) // always false
If String.Empty = Nothing Then ' always true
Should I dismiss this as a typical Microsoft backward compatibility effort, or should I consider this a huge error in the VB.NET compiler? Does anybody know the Microsoftean opinion on this oddity?
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Apr 11, 2012
Is there anyway to check for a null here before it reaches this part of the code? tmpLabelData(0) = m_node.Item("CONTAINER_NAME").InnerText. Some XML has it while others do not. I cant seem to find a nice way to handle a null on these?
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Jul 1, 2009
treeView control which has been plaguing me for the last few days.
I'm not exactly sure what is causing this problem to arise, so I will just explain what my program is trying to do.
I am building an application which will have plugin support. I have created a Plugin interface, which is implemented by each plugin, as well as a host interface, which is implemented only by the host application.
Each plugin has an Action subroutine, and when finished, it is supposed to call the ExecutionComplete subroutine in the host interface.
Now, onto the problem. I have a treeView on the host form, which has several nodes in it. If I create a button on the form which displays a message box with treeView.nodes.count, it shows up fine, and everything works as expected. If I attempt to display the same messagebox from the ExecutionComplete subroutine, it also gives the correct number of nodes.
This is where things get a little weird. I have implemented a save feature into my program, so you can save and load data. For some weird reason, if you have loaded the data from a file, rather than adding each node manually, it now returns an empty node collection ONLY if I try to access it from ExecutionComplete. If I try to access the nodes from a button, it still returns the correct values!
What could it possibly be about the ExecutionComplete subroutine that makes it return a value any different than what is returned when the exact same code is placed in a button click event? And why does it only happen when I've loaded the data from a file? I just don't understand how loading it from a file is any different than them adding the nodes manually. The nodes are definitely being added, as I can see them, and the button click event can also see them. Also, ExecutionComplete is obviously able to read the contents of the treeView, because it works just fine if the user has set up the treeView manually.
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Jul 15, 2011
How to check whether a column is null i use the following code but I got this error "Input string was not in a correct format."
[Code]....
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Apr 2, 2010
I am trying to pull sql data into a text file. The code works just fine, until some new data comes in from lazy employees and a couple fields (used for notes/comments) are now left blank. Originally I've never seen them blank so I didn't think anything of it.
col2 = myreader.GetString(1)
It will error if the field is ever null - I even tried using a case when:
case when note is null then '" & empty & "' else note end and set the variable emtpy = '', but vb still thinks that it's null and errors?
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May 4, 2009
How can I get this to happen? I googled around and it seems setting the CUSTOM FORMAT to " " when the field is null will work but not for a BOUND datetimepicker.
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Nov 2, 2011
Everywhere in this picture you see a blank item, or empty space, a control has failed to draw of something. In this case they are all textboxes.
picture:
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Jun 9, 2009
New to XML. I have a 3rd party webservice that supplies an XML document that I have to update the element values and pass back. The core issue issue is I get an NullReferenceException error when calling the node.RemoveAll() method in the code below. I'm calling the RemoveAll() method because each element has the xsi:nil attribute when it is supplied to me, and if I don't remove it before updating the element value, the XML won't validate by the webservice.The XML document supplied by the 3rd party webservice is as follows:
<?xml version="1.0" encoding="utf-16"?>
<TaskData xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://schema.sample.com/application/1/520800B">
<Global>
[code]....
I've seen have used the XmlNamespaceManager, but I haven't been able to make it work. This xml document has a namespace specified for the TaskData element, and a different namespace for the RequestInfo element. I tried specifying the XmlNamespaceManager variable for each namespace, but got the same results....hovering over the nsmgr variable while in break mode reveals that the "children could not be evaluated" and that the DefaultNamespace property is an empty string.
Public Sub testxml()
Dim doc As New XmlDocument
doc.Load("c: empsample.xml")
[code]....
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Jun 23, 2009
i have a date control on form (vb.net) and by default its value is current date. i want to make its value to null or empty so that no date is shown and user choose from the drop down date calendar.
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May 7, 2010
I am getting the attached error when any cell in a row is empty. How to avoid this error and to accept the null values?
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May 30, 2011
I am attempting to grab an attribute from an XML file and place it in a VB Class as a string. However when i try to run the program, I get a Null Reference Exception on line 21. why I'm getting this and not the placeID (line 2 on XML code)
Private Shared roomDoc As XmlDocument
Private Shared rooms As XmlNode
Private Shared roomList As XmlNodeList
[Code]....
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Mar 7, 2012
I'm deserializing some XML from an old application into an object in my current application. The old XML often has empty elements (<SomeElement />) which are currently deserialized as empty strings (""). I agree that this is the most appropriate behaviour, but it is a minor irritant; I'd rather they were deserialized as Nothing or ideally ignored - the effect would be the same. Is there a means of ignoring these elements? Or can I have them deserialized as Nothing?
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Nov 18, 2010
I am finding this weird issue. When I do this > activities.Where(Function(a) (Not a.IsDeleted And a.ParentId = 100) It returns an in-memory query & when I try opening it up, it throws a object not set exception. This only happens when there were no items which satisfied the condition. Shouldn't it be returning an empty set? When there are items satisfying the condition, then it returns a list & works all good.
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Nov 15, 2009
I key-in data from textbox to datagridvie..........the date data the format datatable is:
[Code]...
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May 27, 2010
I constantly find myself having to do code similar to the following.[code]Is there anyway to check for both on a single line? When i'm checking a condition for a great number of answers, I sometimes end up with conditionals 6-sets deep. If i check for null first, an error still pops up, even though VB shouldn't check since the first condition failed. i.e.[code]
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Jan 12, 2010
How can I change the following code to write to the database null instead of empty strings?
Public Sub SetChangeRequest(ByVal referenceLeaseID As Integer, _
ByVal referenceCustomerID As Integer, _
Optional ByVal custUnitNum As Object = Nothing, _
[CODE]...
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Jan 18, 2011
I have a form and stored procedure that inserts the data from the form. It works fine except that if a field isn't filled in it doesn't insert a NULL into SQL it inserts "".
I've tried a few different ways but none seem to insert NULL, the one below still inserts "", can anyone point me in the right direction?
Here is the required part of the code, if you require more just let me know.
Dim rdr As SqlDataReader
Dim cmdInsert As SqlCommand = New SqlCommand()
cmdInsert.CommandText = "spPersonalDetailsInsert"
[Code].....
So if I enter nothing into address1 field it should write NULL to screen but it always writes NOT NULL. What does an empty form field equal? in classic ASP it was always "".
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Jan 4, 2012
I have a couple of textfields in a Windows form. One of these textfields is allowed to be NULL. When I enter a value for every field, it is all inserted, no problem. When I leave the field (txtGewicht) blank, I can't seem to be able to insert NULL in Access Database.
If Double.TryParse(txtGewicht.Text, 0) Then
klant.Gewicht = Double.Parse(txtGewicht.Text)
Else
[Code]....
This is what I get:
"Cannot set column 'Gewicht' to NULL, please use DBNull instead"
So I changed 'Nothing' to DBNull.value, but it then tells me that System.DBNull cannot be converted to type Double.
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Jun 2, 2012
I have a large one dimensional array that is called ArrayHold which is populated at runtime. I run a loop to scan through the array to find out which elements need to be removed based on a few parameters. This all works great, now I am left with two arrays. The original one and a new one which contains the locations of the elements to be removed.
Original Array: ("A")("B")("C")("D")("E")("F")("G")("H")
Second Array with index/count of elements that needs to be removed: ("0")("3")("5")("7")
End result should be preferably not in a new array but a "ReDim" of the original array:("B")("C")("E")("G")
What would be the simplest way to achieve this? I could run a loop to make all the elements that need to be removed "0" or ""? Would there be an easy way of resizing and array by dropping/removing all the white space or empty elements?
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