Forms - Checking If Values Have Changed
Jun 10, 2010
I'm basically putting some validation logic around an undo button on my form and i'd like to check whether any fields on the form have had their values changed so i can ask the question "abandon changes?". This seems like something pretty standard to me but I can not see how to check whether a value has had its contents changed (without recording a before value and comparing it to the after value which for large forms would be quite horrendous to code).
In the language i used to use we used to walk the object tree (so we dont have to specify each object individually like text box, combo box etc) and check any object that have value-changed = yes to indicate the validation was required.
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May 7, 2012
I have an unbound Datagridview which gets its data from an array from an Excel sheet. I give the user the chance to amend this data in a Datagridview. I then need to know if the user has changed this data before processing it further. I have in vain, tried to use IsCurrentRowDirty, IsCurrentCellDirty, looping through DGV matrix etc. It seems that because the DGV is not bound to a dataset then the normal properties like HasChanged and the 2 above don't seem to work. Here is my attempted code which is not working:
Dim DGRow As DataGridViewRow
Dim DGCell As DataGridViewCell
For Each DGRow In DGV_ReviewDetails.Rows
[code]....
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Sep 20, 2010
I have 22 text boxes that have to be checked to see if the value has changed. I am using the TextChanged Event handler to do this thus:
Private Sub TextStringChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
DataChanged = True
RemoveHandler ........
[code]....
The Handler would be added after the data had been loaded. The question is:Is there another way of checking for text changes without having to add and remove 22 handlers.
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Nov 14, 2010
I am using a class to track if a user cleared their personal information found within some text boxes on a form. In the button click event to clear the text boxes I am creating a new object to the class and assigning true to one property value. Sounds simple until I try and submit the form with a different button, and create a another object reference that I use in an IF statement to check the property value for true. Every time the statement fails because the value being returned from the getter in my class is false.
[Code]...
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Jun 18, 2012
im currently working with an SQL Server 2008 database and im trying to change values in the database usign visual basic.The following code runs correctly and I have tested changing passwords and have been able to logoff and then back on again using the new password. The problem i am facing is that as soon as the application exits the database returns to its origional values so the next time i run the program the passwords are back to the old values.
[Code]...
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Apr 21, 2010
I am using oracle database and i already created a connection and retrieved data from my oracle DB to Datagridview using oledb commands,now my major challenge which has gotten me sick is to update any changes made in the datagridview to the oracle database. I tried using sqlcommandbuilder but failed. This code is what i used to retrieved the data from oracle and place it into the datagridview.
These are my declarations i made at the beginning of the form:
Private myDA As OleDbDataAdapter
Private myDataSet As DataSet
These are the codes inside the search button to load the retrieved data from oracle into the datagridview
Public con As OleDbConnection = New OleDbConnection("Provider=MSDAORA.1;User ID=SYSTEM; Password=simon; database=project")
[Code]
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Jan 5, 2010
I want to edit values in datagrid in VB.NET and also want to save changed value in database. How can i do it?
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Jun 4, 2011
Iam trying to Check Values Of 2 textboxex .. n then Print A certain Amount.
[Code]...
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Jun 23, 2010
I'm trying to make a small program that helps cashiers to practice typing barcode on their machine. Barcode consists 12 numbers, and it can start with 0. Below are the code I worked on so far.
[Code]...
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Oct 18, 2011
I have 14 values, that change constantly. I need to know how to check each value against each other to see if they are within 250 of each other. [code] I want these two values in the listbox to blink red in the list box. but i always want each value to check every value in the list box. i dont even know where to start short of programming each possibilty with a if than statement and that would take forever
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Jul 9, 2010
I'm basically trying to implement the functionality of the example here ax/grid/examples/dataediting/editondblclick/defaultvb.aspx) on my own site, but instead of using a data source control located in the page markup (like in the example: essionDataSource), I'm using a dataset that I get from some server code-behind. I am able to successfully get my double-clicked row into edit mode with my dropdowns successfully
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Nov 4, 2008
I want to check if two combobox values are equal. The comboboxes are in a datagridview.I found you need to use datagridview_EditingControlShowing to add a handler to the comobo boxes for selectedindexchanged. I can do this with this code.
Code:
Private Sub dgridRegisters_EditingControlShowing(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewEditingControlShowingEventArgs) Handles dgridRegisters.EditingControlShowing
Dim combo As ComboBox = CType(e.Control, ComboBox)
[code]....
However, the message box comes up for every combobox in my datagrid when I change the index, not just the cmbPort2. I would like to have something like this...
If cmbPort1.selectedindex == cmbport2.selectedindex then
'do something
endif
..but it doesn't seem possible.
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Jan 14, 2010
Im trying to check to see if a value of a label changes over time. however I can't seem to get it right.
dim val1 as string
dim val2 as string
private sub form1_load()
dim val1 = label1.text
end sub
[Code]...
problem is it will only check it once after ten seconds when the timer is set to 10 seconds i need to to check it every 10 seconds becuase these values display altitude, and if the server freezes the altitudes dont change. I need to make sure they are updated and not frozen.
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Mar 4, 2009
I have a form where when the user clicks the button the values of the form are stored in SQL database. I want to write code in order to check if a specific textbox-value already exist in the database table (in the field "Name"). I 've tried writing something but it doesn't work properly.
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Aug 5, 2009
am new to VB.NET and i was wondering if anyone here knows how to check for duplicate values in strings?
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Jan 22, 2009
How I could go about checking a typed value in a combo to the values in the combo box. I am making a system to select lockerID and Supplier ID I want the user to be able to enter the value in the combo box as well as select the value form the list in the combo box. Here is the code I have been trying.
If cboStockID.Text = "" And cboStockID.Text <> cboStockID.Items.ToString Then
MsgBox("Please enter Stock ID")
Exit Sub
ElseIf cboSupplierID.Text = "" Then
MsgBox("Please Enter Supplier ID")
Exit Sub
End If
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Jan 14, 2010
I have tried to solve this myself and I know I am probably doing something really silly here what I have is two different registry values that control what is displayed in the combobox on my form RegistryKey1 has the following values:0,1 or it does not existRegistryKey2 has the following values2,3, or 4 the combobox has the following values 0,1,2,3 However here is the problem if the RegistryKey2 is 2 then it further has to be checked if RegistryKey1 is either 0,1 or does not exist
if it is 1 then the selectedindex = 0
if it is 0 or does not exist then the selectedindex = 1
if RegistryKey2 is 3 then the selectedindex = 2
[code].....
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Mar 30, 2010
as title says. and if it has the same values, delete one of them and add (2)
so itll be like: - before the filter:
[Code]....
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Aug 3, 2010
i am making an RPG game with visual basic...The character is a picture box.The problem is when i move the charactor with the arrow keys it flashes black for a milisecond. I think added animated walking where it slowely moves 32 pixels but not it goes black the whole time... what can i do sto stop it going black everytime it moves?
Old movement
If e.KeyCode = Keys.Right Then
player.Image = My.Resources.mainplayerright
moveto = New Point(playerx + 32, playery)
[code]....
That code moves the player slowely but causes a big black line to merge then just ends up teleporting the player..How can i get rid of the black flash during movement?
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Apr 14, 2011
I have a form where two fields on the first page of the form make up the primary key. I want to check for duplicate values before attempting to insert the record, since I don't want the user to go all the way through the form only to find out they can't submit it. So I'm trying to check for duplicate values when the user tries to go to the next page of the form. I wasn't quite sure how to do it, and sure enough I'm getting an error. ("Object reference not set to an instance of an object.") The problem is apparently in my if statement, "If myValue.Length > 0 Then", but I'm not sure what needs to be in place of that.
Protected Sub CustomValidator1_ServerValidate(ByVal source As Object, ByVal args As System.Web.UI.WebControls.ServerValidateEventArgs) Handles CustomValidator1.ServerValidate
'get values
[code].....
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Feb 20, 2009
I have declared a class in VB.NET using VS2K5 with some shared variables and made that class a dllI made use of that dll in another project and tried to make use of those variables. Even though I can able to make use of them, Im unable to view the values of those variables like the values of normal variables when Im debugging. Is there any way that I can watch the values of those shared variables during debugging.
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Apr 3, 2009
I have a DataGridView1 populated by sql searches. On the rare occasion that nothing is returned, my app cannot make use of data so I'm trying to check for null values. My code below is not correct because IsDBNull is not a member of the of the DataGridView1.
If DataGridView1.SelectedRows(0).IsDBNull Then
MsgBox("Nothing to display")
Exit Sub
End If
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Oct 19, 2009
I am using Vb 2008. I have created label array in run-time(Dynamically). I have put them in Panel1.
Dim loc As Integer
loc = 5
For i = 1 To 25
NewLabelMe(i) = New Label
NewLabelMe(i).Text = "99.99"
[code].....
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Dec 26, 2011
Basically I have a form which has 2 drop downs. In the 1st drop down I am selecting City category. When the city is selected I want to update the 2nd drop down values in correspondence to 1st value choosen in 1st drop down. I have done like this,This adds the value in the 1st Drop Down:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim s As String = "connection String"
sqlconn = New SqlConnection(s)
[code]....
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Oct 31, 2011
I've never really used the Check List Box in the past, however, for the recent program I am developing, I am using this control rather than individual check boxes scattered across the form.Anyway, I want to be able to program through code which items get checked in this checked list box. Specifically, I have a variable that contains the text of each check box that I want checked.With a normal check box, I can simply say:
Dim strNames As String
strNames = "John Doe, Mark Johnson, Mike Brown, Cindy Smith"
If strNames.ToString.Contains("Mike Brown") Then[code]....
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Aug 3, 2009
I'm very green with VB Express 2008 and am going through the tutorial. I'm skipping over a lot of the exercises as some of it is review for me - I've a fairly solid background in MS Access VBA and forms design there. But I have a simple question on VB Express forms design (I'm not worried about data handling or anything yet).How do I test a form? In my first form on my project, I just press F5 (Start debugging) and it opens just fine. However, I'm playing around with a second form in design mode and can't seem to get it to open to test some of the code (simple msgboxes associated with buttons).
In Access 2003 and earlier, there was a design mode and form view. The Access design mode was the equivalent of the design tab in the VB project, but I can't seem to find the equivalent of the Access form view in VB so that I can open that form. VB F5 only seems to open the first form.BTW, is VS 2008 the correct tag/prefix for this question on VB Express 2008? I see there's a separate tag list - is there an approved list of tags aside from the prefix before the title in the posting screen?
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Feb 17, 2011
I am making a virtual crafting application (similar to that done in Minecraft)
currently I have made a test "crafting recipe" which checks if the listbox (mixbox) has 1 window, 1 door and 1 wheel. the code looks like this:
If mixbox.Items.Contains("window") Then
If mixbox.Items.Contains("door") Then
If mixbox.Items.Contains("wheel") Then
[Code]....
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May 5, 2012
I changed my Username on my computer from i.e. "xxxxxx x xxxxx" to "Dennis"
VB 2008 during a compile gave me the following error: Error reading icon 'C:Usersxxxxxx x xxxxxAppDataRoamingMicrosoftVBExpress9.0VSProjectApplication.ico' -- The system cannot find the path specified.
The file "VSProjectApplication.ico" is in 'C:UsersDennisAppDataRoamingMicrosoftVBExpress9.0'
Somewhere in the VB2008 "configuration" files I believe that I need to manually change the old path to the new path.
I found the old path in the ".suo" file. The ".suo" file is not a text file. How can I edit the .suo file, save it so that it will work?
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Jan 28, 2011
So I'm writing the equality operator overload (Operator =())for a custom object, and the resulting mess of If conditionals is just an eyesore. But so far, it seems like the only sane way to check the values to as to match the specific behavior of this object.
The rules are:Num1 is required, period, and both the left and right operands and must be equal for True. Else, False.Num2 is optional, but if specified, must be present for both the left and right operands, and must be equal for True. Else, False.Num3 is optional, but can only be specified if Num2 is also present. Else, False.Num3, if specified, must be present for both the left and right operands, and must be equal for True. Else, False.
[Code]..
I also know that I could cache elements of the checks into booleans and then use those to reduce the amount of text. But that seems like a waste of cycles just for code readability. So I wanted to know if the SO community had better thoughts on reorganizing it, just in case I'm being too verbose with my checks.
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Feb 2, 2011
I have a form which asks for a username and password to connect to a MySQL database. Before I load the login form I would like to place a check to see if the connection information is stored in the My.Settings.<connection string..I am using Sub New() in the Form.Designer to do this by placing the following [code]The connection form does show but when i close the form there is a blank form that shows up.
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