DataRow.Delete Method Responds With Erroneous Behaviour
Dec 4, 2009
I'm working with a disconnected dataset that is NOT using a database. I'm maintaining an external file in xml format using the ReadXML and WriteXML methods of the dataset. I have a Holiday table structure in the dataset with the following columns:
-HolidayDate
-HolidayName
When the app starts I read the Holidays into the dataset. I then check the Holiday table to see if any of the Holidays are in the past. If so, I want to delete the given Holiday row from the Holiday datatable. I'm running the following code: [code] If the HolidayDate is in the past it calls the Delete method ok but when it tries to execute the Next statement it raises an InvalidOperationException exception with the message "Collection was modified; enumeration operation might not execute".
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Apr 9, 2012
I'm trying to delete the selected row in a gridview from the datatable but it seems like it's not deleting. in if statment Table.Rows.Count = 0 is not working and I'm trying this with one row in the grid view.
Protected Sub GridView1_RowCommand(sender As Object, e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles GridView1.RowCommand
Dim index As Integer = Convert.ToInt32(e.CommandArgument)
[Code].....
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May 1, 2010
I'm going through a book which is teaching me some basic coding principles of the language. The current section is detailing how to set up a master child form using two tables linked with a foreign key. The master table is displayed as a number of text boxes, and below is a grid with the child table which shows related records to whatever master record you happen to be checking out. At the top of the screen are the default navigation controls that are added with the grid. The master table is named Person and the child table Book. They are linked using a foreign key and have cascade set up on them.
The book informed me of the code required under the save icon on the navigation control so that when it is clicked both tables will be updated as required. It is as follows:
If Validate() Then
'Make sure editing has completed on both master and child tables
Me.BookBindingSource.EndEdit()
Me.PersonBindingSource.EndEdit()
[Code] .....
I have double checked that the code matches that shown, so this should in theory work fine. But if I manually delete a record from the Book (child table) grid and then click the Save icon on the navigation bar it comes up with the error "Update Requires A Valid DeleteCommand when passed DataRow collection with deleted rows".
Why changes made are not permanently saved to the database? I gather that it's using a "copy" of the data in the database but how do I get the code/form to make changes to the actual underlying database records as well as just the copy? I find this system very unusual, if someone deletes a record in the application why would anyone want this to be just done temporarily?
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Jun 10, 2010
My apologies I have posted this in the wrong catagory It should be in VB.net, my mistake)Hi guys I posted this question at the end of another topic I started but I think it will be over looked as the origional topic was solved of the dreamincode community You must all be getting sick of my quexstions by now haha I suppose you don't learn if you dont ask.
Anyway I have used the delete sql method to delete data from a database, I want to refresh the data in the form after the record has been deleted. Do I have to close the form and then open an new instance of it? or is there another way I can refresh the data?
[Code]...
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Mar 14, 2009
My question is: how to delete a specifically cell in sql datarow from a specifically datatble to insert i have the folowing
Dim AgendaData As New AgendaData AgendaData.TijdDagWeekJaar = TijdDagWeekJaar.Text AgendaData.WeekJaar = WeekJaar.Text AgendaData.JaarMaand = JaarMaand.Text AgendaData.Jaar = Jaar.Text AgendaData.textbox2 = onderwerp1.Text AgendaData.textbox3 = Onderwerp2.Text AgendaData.textbox4 = Onderwerp3.Text AgendaData.textbox5 = Onderwerp4.Text AgendaData.textbox6 = Onderwerp5.Text
[Code]...
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Apr 9, 2011
I have a delete method for a binary search tree. It only deletes the last two entered values. When trying to delete the root or anything to left of it it returns a null pointer exception.
PublicFunction Delete(ByVal key AsInteger) AsBoolean Dim current AsNode = root Dim parent AsNode = root Dim isLeftChild AsBoolean = True While (current.value <> key)
parent = current If (key < current.value) Then isLeftChild = True current = current.rightNode Else
[code].....
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Sep 13, 2009
May i ask you based on your codes last time to create a button, is this how i modify to delete off the button after i clicked on it? So that means to say i click on this button at location 15,41 then only this button will be deleted. the below is my code to delete the button but it is not consistent as sometimes it can delete more than one button when i click on one button.
Dim dr As DialogResult = MessageBox.Show("Are you sure?", "Check", MessageBoxButtons.YesNo)
If dr = Windows.Forms.DialogResult.Yes Then
PictureBox1.Controls.Remove(BTN)
[code]....
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Feb 25, 2012
iam working in a project autocomplete in comboboxes respond's too slow ,but there is a form have too many control's on it when i remve it autocomplete working fine ,but i can't Dispense this form.
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Oct 1, 2008
My Application contains a button and two text boxes. 1st textbox is for user input known as tbHost.Text 2nd textbox is for displaying results after button is clicked, this is set to readonly. The button is a start button that will call a new process every time it is clicked. I intend to let user to have a choice to either click on button to display result or press enter key to display result.
[Code]...
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Apr 8, 2009
OK this is my third thread on TCP problems and the first two I managed to figure out for myself within 10 mins of posting before anyone had a chance to reply so lets see if it works again - failing that if you have any advice I'd be most grateful.
I have a server app which should be sitting and listening for messages on one port (4000) and then processing requests and sending data back via another TCP client on a different port (4001). My code is based on someone else's example and it works fine sending and receiving the first message, however after the first message the listener seems to stop listening and never gets any further messages.
Am I misunderstanding how they work? After I get the first message do I need to close the listener and create a new one, or should the same listener keep working until I close it?
[Code]...
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Apr 5, 2011
I have a GridView and on a row being deleted I trigger the GridView1_RowDeleting sub, but I receive an error "LINQ to Entities does not recognize the method 'System.Web.UI.WebControls.TableCell get_Item(Int32)' method, and this method cannot be translated into a store expression." Code 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.
[code]....
The specific line erroring out is:
remove_bed.First.occupant = ""
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Apr 9, 2011
I have a delete method for a binary search tree that only deletes the last two values that were entered in, and when it tries to delete anything to the left of the root or even the root itself it returns a null pointer exception.
Public Function Delete(ByVal key As Integer) As Boolean
Dim current As Node = root
Dim parent As Node = root
Dim isLeftChild As Boolean = True
[Code]...
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Jun 15, 2012
Which method is professional to insert, update, delete data using either MS Access database or SQL database?
1) Using wizard to connect the database
2) Writing code manually such as
"INSERT INTO CUSTOMERS(CNO, CNM, CTY, TEL, TDT, NTS, UID) VALUES(@CNO, @CNM, @CTY, @TEL, @TDT, @NTS, @UID)")
I need to insert data from one form (Collection_Form) to 2 database tables. Like, Collection form data to be added in the following 2 tables:
1) Customer_Account
2) Collection_Account
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Sep 8, 2009
I am having trouble with XMLTextWriter.WriteStartElement throwing an exception:
System.InvalidOperationException
when trying to write the second element in my XML document. This error comes back as "The Writer is closed". I have not closed it, so I am guessing it has fallen out of scope?? I have created a class to write an XML file using XMLTextWriter as an object within my class. Below is the relevant code. I have found one other post on codeguru that was never answered with the exact same issue.
Function CreateXML()...
Try
_listDocument = New XmlTextWriter(_xmlDI.FullName & "\" & currentFilename, Nothing)
CreateHeader()
[code].....
I am calling these functions after instantiating a dimension from ListXML (the name of my class) with the following code:
Dim xmloutput As New ListXML
xmloutput.CreateXML()
xmloutput.AddListMember(xmloutput.ReturnWhiteList, currentItem.SenderEmailAddress, xmloutput.ReturnAddAction)
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Jan 16, 2011
i have one project in which i am using listbox as display to let user know what software is doing internaly, this include i/o opration.The problem is listbox is late when the operation is fnished then it respond,s
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Mar 11, 2010
The goal -- use VB.Net to write a windows forms application that responds to a limited set of voice commands after the user says a keyword, (such as "Wake Up"). I have the following code I am using from another site but I am getting an error I do not understand (nor do several others who posted comments at the same site.)
Imports System
Imports System.Data
Imports System.Deployment
[Code].....
If I had any understanding of how to create a grammer file I MIGHT be able to avoid this error completely, since I am only interested in a few voice commands (maybe 30), not the whole 60,000 word dictionary.
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Jul 31, 2009
1st, i try to "add", "save", and "delete" DataRow in DataGridView using Button in the same Form. I try to search in the internet but i cant find it at all.
Public Class FrmReminder
Private Sub BtnBack_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnBack.Click
[code]....
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Apr 28, 2010
I have two datatables with similar structures that I want to make one existing row to be updated from another datatable.
For example, "tableA" has three columns: "one", "two", and "three"; with "one" being the primary key...
and "tableB" has three columns as well: "one", "two", and "three"; with "one" being the primary key.
Say there is a row on tableA that is different than a row on tableB (with a matching primary key). What I wanted to do, as efficiently as possible, is to take the that row from tableB and replace the one on tableA so it'll be modified.
I'm not sure if there's an easier way of doing that instead of using loops for setting the row's items.
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Mar 11, 2011
In a program I am using the standard PrintDocument, PageSetupDialog and PrintPreView controls. I am attempting to print a screenful of information which covers three A4 printed sheets. The printed format is OK except that the positioning on the page. Changing the margins in the PageSetupDialog makes it worse.So I wrote the following code in the Form Load event to see what was going on -
While
True
Dim
MsgStr As
[code]....
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Sep 12, 2011
I have an application which was developed in vs2005 with numerous forms which use the combobox for selecting from lists of items. The usual setup is as follows:
Combo.Datsource = BusinessObject
Combo.DropdownStyle = DropDownList
Combo.AutoCompleteMode = SuggestAppend
Combo.AutoCompleteSource = ListItems
However, compiled under vs2005 when tabbing to a combo and typing a number of characters the combo would highlight the first matching item and on pressing tab, would select it and the user would move to next field.
With vs2008 the same item might be highlighted but pressing tab doesn't select the item unless its the only item matching the first character. The only way of selecting the item highlighted from the suggestappend is to press enter prior to the tab key.
I also noticed some users experiencing the same behaviour when the app was compiled with vs2005 on some PC's but not others as if it had something to do with the PC config.
Has anyone any ideas how to get around this as it can lead to errors in data capture.
Kind regards.
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Jan 26, 2011
I never used POCOs, so I have the habit of putting a lot of logic in my business object classes. Hence I believe I'm missing some important concepts about class-layouts, and the thought-process that is needed here.
Say if you have two classes; Company and Employee. Could you give some examples of what classes you would build "around" these that take care of various behavior/validation etc.? (Like some class names, and a brief description of their purpose)
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Oct 13, 2010
i am working on an application which calls the COM component of a partner's application.Ours is .Net, theirs isn't. I don't know much about COM; I know that the component we're calling is late-bound i.e.obj As Object = CreateObject("THIRDPARTY.ThirdPartyObject")We then call a method on this COM object (Option Strict Off in the head of the VB file):obj.AMethod(ByVal Arg1 As Integer, ByVal Arg2 As Integer, ByVal Arg3 as Boolean)I am a bit nonplussed that even though this call works, this overload doesn't exist in the COM interop .dll that is created if I instead add a reference to the COM server using Add Reference. The only available call to this method that it says is available is AMethod().
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Oct 19, 2010
Consider a MyForm class that contains a shadowed implementation of Show(). It also contains a CreateForm() method, which accepts an instance of the form and calls the shadowed sub:
[Code]....
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Jul 22, 2011
i am very new to VB. I am working on file operation such as show files, copy file, delete file, show current directory, rename folder, make folder. My problem right now is with delete and copy file. I have a method of delete and copy but i dont know how to pass this method on a button.
[Code]...
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Mar 11, 2009
I'm using the following code to connect to a IDM webspere message queue to try and pull a message from the queue.the HTTPWebrequest method neets to be DELETE to pull the message and revoce it from the queue.However when yousing the code below i get the following error:Quote:Cannot send a content-body with this veb-type
Code: Private Sub btnGet_Click1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGet.Click Dim objRequest As HttpWebRequest = HttpWebRequest.Create("http://webspere/mq/msg/queue/INSURANCE.TO.PRISM") Dim
[code].....
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Oct 7, 2011
My ASP.NET (VB.NET) application uses SiteMaps to display a navigation menu on the top of each page. In the code behind of some of the pages, I am dynamically amending the URLs of the SiteMaps nodes (to add parameters to the end of the URL) e.g. say I have somePage.aspx.vb and anotherPage.aspx.vb and they both contain the following:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
AddHandler SiteMap.SiteMapResolve, AddressOf Me.ExpandForumPaths
If Not Page.IsPostBack Then
Setup()
[code]....
My problem is this, if I am in the code behind of somePage.aspx and I do a Response.Redirect("~/anotherPage.aspx") - then, when anotherPage.aspx.vb is being loaded, it is the ExpandFormumPaths method of somePage.aspx.vb that is hit, not that of anotherPage.aspx.vb.
My understanding is that a Response.Redirect tells the browser to do a new request to the supplied URL - I don't know why it's hitting the method belonging to the previous page.
I've tried amending the method names (i.e. not having the node processing method called ExpandFormumPaths in all classes) but I still encountered the same issue.
When I go straight to the URL of anotherPage.aspx the correct method is hit, it is only when I am using Response.Redirect that this happens.
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Mar 8, 2012
Basically, IHTMLElement5 and IHTMLElement6 are all extended interfaces for the main IHTMLElement as per the versioning rules below:
IHTMLElement IE4
IHTMLElement2 IE5
IHTMLElement3 IE5.5
IHTMLElement4 IE6
IHTMLElement5 IE8
IHTMLElement6 IE9
Of course, each new extended interface has the old members in it + its own new members, properties etc. However, some of the members (for instance, .getAttribute) are the same name but have been updated. So, my question is, if I use (say) IHTMLElement6 to declare my HTML Element and run the code on a client that only has IE6 installed, when will my object just fail and remain as Null/Nothing when I set it, or is mshtml.dll smart enough to realize whats going on and defaults to IHTMLElement4 (actually, IHTMLElement) behaviour?
Just to clarify the last statement in brackets, .getAttribute was added in IHTMLElement and updated in IHTMLElement5 and IHTMLElement6 - so, if someone has IE6 installed only, then I would expect the behaviour to default/revert back to IHTMLElement (not IHTMLElement4) - and if it does not do that, then I expect my code to crash. Basically, my question is, what will happen exactly?
Summary of Question (read if you find necessary, just a reclarification for those who need it):Basically, I want to be able to declare something as IHTMLElement6 so I can make use of the updated methods which have the same name between IHTMLElement and IHTMLElement6 (such as .getAttribute). This way, on IE9 users IHTMLElement6's version of .getAttribute will be taken advantage of, while at the same time IHTMLElement's version of .getAttribute will still work for (say) IE6 users without breaking my code - this is the point where my question comes in, when using a IHTMLElement6 object, even though it is an IE9 interface, will IHTMLElement's (IE4 interface) version of .getAttribute kick in/work or will I get a null reference exception or other runtime error?
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Sep 5, 2010
1. create a blank VS2010 web project called "MySite" targeted at 4.0
2. create a new class object, calling it "class1.vb" (cause it's so unique!!)
3. change default code to read as such...
Namespace MySite
Public Class Functions
Public Shared Function WhatIsTodaysDate() As String
Return Date.Now.ToLongDateString
[code]....
Why is VS asking me to call the namespace twice if I use the "Imports" directive?I'm sure this has got something to do with VS2010 and the 4.0 framework.
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May 29, 2010
This works:
Dim zArray(5) As String
zArray = (From zS As String In zArray Select "HelloWorld").ToArray
This doesn't:Dim zArray(5) As String = (From zS As String In zArray Select "HelloWorld").ToArray
It seems inconsistent to me, though I may be missing a subtle difference instead of it being an IDE inconsistency?
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May 6, 2009
If VB5/6 could read Unicode I would remain in it for ever as it is to me the most efficient way of getting all things done, and I have likely done more in VB classic than most care to try on VS.NET Now, in the midst of trying this system I keep a red light lit in the back of my head, on constant alert due to the GC part of .NET.
No matter what I read, I just get more precarious about the implementation of a Garbage Collector in VB, as this means I cannot absolutely say that a username and password is cleared from memory when I want to.In spite of tallking directly to Mr Bjarne Stostrup (the inventor of C++) and reading two ebooks of a few hundred pages each over the past night, some things still boggles the mind.
Such as...Why in heavens name does the MSDN library opener say "Help is updating to reflect your recent changes. This may take several minutes"Well its not so bad if it happend once, as on the installation of the MSDN disks, but when it happens EVERY TIME that I open MSDN or VS2008, that makes me wonder.Especially when I just closed VS2008 and opened it again five minutes later.
The latest "update" according to the MSDN opener took not only a few minutes but approx. 20 minutes, although I did nothing to change anything since the last time I opened it.Is there any way to disable this constant updating of nothing?
Once more back to the GC issues.Does anyone have a simple to use class, so that at my will I can issue a simple call to a method to clear anything and everything unused from the GC box, short of having to close my application and reopening it?I mean, would it be to much to ask for a simple command that allows us to do this, without having to "imrpove on the MS developers years of efforts" by our own non standardized methods?
What I would like to see implemented in VS.NET would be a simple thing for the boys and girls at Mr. Gates command, to add the following
....GC.ClearAllDead
When called, it guarantees to clean the GC, empty all unused addresses and simply Dispose and Finalize everything at our will, and not leave this sometimes time and security critical part to the will of a users sometimes slow and willful PC.
Everyone knows how easy it is, and common to date that you load a webpage with some flash or adobe files and your computer starts sounding like a spaceship ready for relaunch.Quite obviously, something is running up your CPU and memory usage, and doing things you did not ask it to do when going to read your blog pages for example.Often I have experienced this, and still do on a daily basis, and I sweat every time I think of the possibility any application starts accessing memory addresses to scope up whatever junk is left in memory.Coupled with Garbage Collection potentially leaving items in memory addresses until it wants to free this itself.Now what if someone sneaks a trojan of a new variant onto your system, and this constantly sniffs your RAM for new funny and useful code.
there went your UID/PWD combo to both online banking, blogs, GMAIL, hotmail and all other nice things you use. Consider yourself facebooked in a nasty way, and then tell me GC is all good and poses no risks.So, the addition of the simple GC cleaner above would have been, and should have been, in my oppinion, the first and foremost update to the .NET package before it even was released, thus making it easier and faster for new and old programmers to avoid this cause for (perhaps to be considered as) paranoia.With my background from security and time critical related work, I would still prefer to patch the holes before they become an issue, and I will continue to chose being paranoid and safe rather than leaving this potential hole open.
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