Avoid Getting Empty Fields In A Databound Combo Box?
Oct 18, 2010How to avoid getting empty fields in a databound combo box?
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Avoid Error When Displaying Empty MS Access Fields In VB?
Feb 15, 2012I have a database with lots of fields, some of which are still empty and are to be filled in at a later stage. Is there any way of writing an IF statement (or any other method) that will allow these empty records to be 'shown' in my textboxes in Visual Studio, without receiving the error:
Conversion from type 'DBNull' to type 'String' is not valid.
Avoid Getting Empty Fileds In A Data Boud Combo Box?
Oct 18, 2010How to avoid getting empty fileds in a data boud combo box?
View 1 RepliesUse A Databound Combo Box To Display One Field In The Drop Down And Another As The Combo Box Text On Roll Up?
Feb 21, 2012How to use a databound combo box to display one field in the drop down, and another as the combo box text on roll up? Using VS 2005... For example, I have a datatable that has 2 fields. One called "ShortDesc" and one called "LongDesc". I want to be able to see the "LongDesc" column values in the drop down on the combo box. When I make a selection, I want the text in the combo box to read the corresponding "ShortDesc" value.
[Code]...
Adding An Empty Row To A Databound Listbox Using Linq2SQL And Winforms?
Sep 28, 2011what is the most robust method for adding a empty row (to select "nothing") to a ListBox?
Dim List = Enumerable.Repeat(New TABLE With {.Text = "", .ID = -1}, 1).AsQueryable().Union(From t In mainctx.TABLEs)
ddlMangelKategorie.DisplayMember = "Text"
ddlMangelKategorie.ValueMember = "ID"
ddlMangelKategorie.DataSource = List.ToList
But this has some drawbacks:wordy must explicit write the Type (TABLE in this case), so i cant wrap this in a function have not found an solution, which works with anonymous types I.e. if I add a From t In mainctx.TABLEs Select Text=col1, id=col2 to the query, this method does not work anymore.
Refresh A Databound Combo Box?
Nov 9, 2011I have a program where a user can select something from a combo box in a data grid view control. I have it so that they can add something to the combo box via input box. The new item would automatically show up in the combo box at the bottom.
Now the problem is with deletion. I have it so that a user will click delete and a dialog box will pop up with the combo box. There a user will select an item and click delete. The item deletes just fine from the db but it doesn't update the combo box on either the delete dialog box or the datagridview. The only time it shows deleted is when I exit the program and reload.
Here is my load event that populates everything.
Public Sub LoadData()
Try
Dim cmTasks As New SqlClient.SqlCommand("Select * from Tasks where Department_ID =
[Code]....
Databound Radio Button Class When Database Table Empty
Apr 13, 2009The problem I have is that many times, the dataset that this control is bound to is empty. Therefore, the user continuously gets an error saying that one or more fields is missing. When I debug the code, I can see the code in the class loop through all of the radio button controls on the form. Since none of them match the field from the database, the code throws the error. I assume the code expects a match.
Should I modify the class to handle the case when there is a DBNull value? If so, what would be the best method? Or should I approach this situation in a completely different manner?
Public Class myGroupBox
Inherits GroupBox
Private _myTag As String
[Code]....
.net - Databound Combo SelectedItem Doesn't Seem To Work
Jun 12, 2009I'm attempting to bind a combo to a collection of objects:
Dim t As New TradeOrderStatus()
Dim ts As List(Of TradeOrderStatus) = t.GetStatuses
With Me.cboTradeStatus
[code]...
This works fine and I see the list of items in the combo. However when I try to set the SelectedItem of the combo to one of the items:
Me.cboTradeStatus.SelectedItem = Trade.TradeStatus
nothing happens. Trade.TradeStatus is an instance of the class TradeOrderStatus and all the necessart statuses are visible in the drop-down list. The SelectedItem remains as Nothing (or as the first item in the list if I omit the .SelectedItem = Nothing line from the binding code).
Debug.Print(CStr(Me.cboTradeStatus.Items.Contains(.TradeStatus)))
also returns false.
Adding A Blank To A Databound Combo In A DataGridView
Apr 27, 2010I've inherited a form that has a DataGridView that is bound to a dataadapter and it is connected to a binding source. Within the DataGridView is a combo box that is bound to its own bindingsource which basically just calls a stored proc to bring back the possible values for the dropdown combo control
With a blank new row and sometimes even with an existing row, this value for the combo box can be NULL which is a legitimate value for it if no value selected. Problem is everything is so tightly bound if the user mistakinly clicks the dropdown then a value is populated and there's no way to get back to NULL
I've tried to catch the mousecelldown event and others to try to catch this before a value is selected but the Cancel=True doesn't work - I can catch the event but don't know how to return the cell to unclicked or reset it to NULL or pre selected value if NULL I know how to at a new row with the datatable and then set the combo datasource to it and I have my null blank value but with a tightly bound control how do I add this row?
Pizza Shop - Take Orders - Populate Text Box From Databound Combo Box?
Sep 28, 2010got a pizza shop and the assingment is to create a application which alows the user to take a customer's order... I have a combo box filled with all of the items you can order (data from an access file)... and I need to have it so that when you select an item, it shows up in a text box below... I keep getting an error message saying you can't convert datarowview to string..
here is some
Private Sub TakeOrders_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'PROJECT4DataSet.Items' table. You can move, or remove it, as needed.
Me.ItemsTableAdapter.Fill(Me.PROJECT4DataSet.Items)
End Sub
[code]....
Avoid Context Menu From Combo Box Control?
Aug 27, 2009I want to avoid paste operation in combox box control. to suppress the system context menu for copy and paste, I did following steps1) Create a empty new context menu (just drag drop new context menu on the form)
2) Assigned newly created empty ContextMenuStrip to combo box ContextMenuStrip property. Is it the right way to avoid right click system context menu? is there any other way to do so?
Avoid The Closing Of A Combo Box Popup Window In Datagrid
Jan 30, 2012How To Avoid The Closing Of A Combo Box Popup Window In Datagrid? I was trying to block the closing of a custom combo box popup window in my custom DataGrid. The popup window comes by pressing F4 or ALT+DOWN keys which is getting closed if I press the down arrow for the first time after showing the first value in the combo box as selected. Next time onwards, if I press the F4 key and down arrow, I can move to any item in the popup window and select the item using keyboard and in that case, the popup window is not getting closed till I press the ENTER key or selection using the Mouse. Is there any specific reason for this behavior or something is missing in my code part?
View 3 RepliesVS 2010 Testing For Empty Fields?
Mar 14, 2011I used to run into problems with this in VB6, too...
If Not ds_Students.Tables(0).Rows(0).Item("ClassDay2").IsNullOrEmpty Then
txtClassDay2.Text = ds_Students.Tables(0).Rows(0).Item("ClassDay2")
End If
This produces "Public member 'IsNullOrEmpty' on type 'DBNull' not found."
And is there a different test for fields of different data types?
VS 2008 Passing Empty Fields To SQL Table?
Nov 9, 2010I'm trying to add a service company from a vb form to an SQL table. It works as long as I enter something in every field on the form. If not I get a syntax error so I thought I should check that the field values were not null
I've tried to add a sub to check for blanks but it's not working
btw the table will allow nulls for all fields
Private Sub btnSubmit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSubmit.Click
Try
[Code].....
MySQL 'UPDATE' Command Returns As Empty Fields?
Feb 27, 2011I am building a vb.net application for a client, and there is a problem. I am connecting to a mySQL server, and using the UPDATE command to update certain fields to the specified values, however, once I run this code, the fields on the mySQL server turn EMPTY. Here is my code :
Sub updateresidents()
'MAKES NO SENSE; UPDATES EMPTY FIELDS ON mySQL SIDE??!!!!!!!!!!!!!!!!!!
Dim connection As MySqlConnection
[Code]....
Skip Empty Database Fields And Goto Next Step
Dec 4, 2009How to tell the program that if the field is empty to skip it and go to the next step. I have tried IsEmpty (but it tells me the variable IsEmpty was not declared), I have tried to use different If statements but in most cases I get the message
"Conversion from type 'DBNull' to type 'String' is not valid."
I tried using an integer variable and setting it to
'Test = CStr(dt.Rows(I)("socSecNumber")).Length'.
It works for the first step (which makes sense b/c socSecNumber is never empty), but when I set the 2nd and 3rd ones
(TestFName = CStr(dt.Rows(I)("firstName")).Length TestLName = CStr(dt.Rows(I)("lastName")).Length If TestFName > 0 And TestLName > 0 Then...)
Then I am back to getting the message
'Conversion from type 'DBNull' to type 'String' is not valid'.
I do not know anything about recordset and when I did try to use it it displayed the message something like 'get and set are no longer allowed'.
The entire function is below:
Private Sub BtnCreateLetter_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnCreateLetter.Click
Dim SSN As String = TxtBxSSN.Text
Dim dt As New DataTable()
[Code] .....
Is it possible to include something in the SELECT from table? Such as:
"SELECT * FROM" & Students & "WHERE" * NOT DBNull
or
I do not know if it is possible to use variables in the SELECT from table code but if it is I thought perhaps could make a variable named FieldContents and pass it to a function that would do something like:
"SELECT * FROM" & Students & "WHERE" * FieldContents LIKE '[A-Z]'
Returns The Property Names As Column Headers And Empty Fields?
Jun 14, 2009why this code returns the property names as column headers and empty fields?
Dim table As New List(Of SalesPersonClass.SalesPersonClass)
Dim i As Integer
For i = 0 To salesPeople.GetUpperBound(0)
table.Add(salesPeople(i))
Next
dgSalesPeople.DataSource = table
Function - Method Or Routine That Converts Currency String In A Databound Textbox To Decimal And Ignores Empty Strings ""
Jun 12, 2011As the title says I have a form with many databound textboxes. some of these boxes have data in them and some are empty. I need to add them altogether, so far all of the conversion methods I have tried err out when they run into an empty string, except Val, but then Val won't handle the string with a $ in it. I've tried decimal.parse which handles the $ but not the empty string. So I seem to be in circle that I can't get out of.
View 2 RepliesFill A Combo Box With The Names Of The Fields Of A Table(from A SQL Database)?
Jan 22, 2009Is it possible to fill a Combo Box with the names of the fields of a table(from a database)?
View 6 RepliesCombo Box Selected Item Is Null - Assign An Empty String To It Instead?
Dec 9, 2011I have a property called ReplacementTo and I set a value to it based on the selecteditem from the combobox, like this:
classEquipmentItem.ReplacementTo = cmbReplcmnt.SelectedItem.ToString
Now I can't use cmbReplcmnt.Text because what I actually need is the value of that SelectedItem
So problem is, if the user leaves the combobox as blank, it throws a null exception.I decided to use the IIf function then:classEquipmentItem.ReplacementTo = IIf(IsNothing(cmbReplcmnt.SelectedItem.ToString), classEquipmentItem.ReplacementTo = "", cmbReplcmnt.SelectedItem.ToString)
Unfortunately I still get the error I tried using a Try-Catch for it and it worked, but I don't want to rely on the Try-Catch, so I was wondering is there a another way to work this through?
Avoid Closing Of A Custom Combo Box Popup Window In A Custom Datagrid?
Jan 31, 2012I was trying to block the closing of a custom combo box popup window in my custom DataGrid. The popup window comes by pressing F4 or ALT+DOWN keys in my datagrid which is getting closed if I press the down arrow for the first time, after showing the first value in the combo box as selected. Next time onwards, if I press the F4 key and down arrow, I can move to any item in the popup window and select the item using keyboard and in that case, the popup window is not getting closed till I press the ENTER key or selection using the Mouse. Is there any specific reason for this behaviour or something is missing in my code part? [code]...
View 1 RepliesAvoid The Closing Of A Custom Combo Box Popup Window In A Custom Datagrid?
Sep 2, 2010I was trying to block the closing of a custom combo box popup window in my custom DataGrid. The popup window comes by pressing F4 or ALT+DOWN keys which is getting closed if I press the down arrow for the first time after showing the first value in the combo box as selected. Next time onwards, if I press the F4 key and down arrow, I can move to any item in the popup window and select the item using keyboard and in that case, the popup window is not getting closed till I press the ENTER key or selection using the Mouse.
View 13 RepliesVB 2008 Datagrid View With Access 2010 Lookup Fields And Combo Box Not Working
Mar 1, 2011I started a forms solution in VB 2008, created a datasource to an access database (2010) and used the datagrid view to display the data. 3 fields in the access database are lookup fields with 2-8 values each, typed in by me, since the linking to other fields did not work. This is not working either. When I change the column to combo-box or not, those values, typed into access, are NOT showing up in the datagrid. the combo box has its drop down arrow but the value fields are empty.
View 10 RepliesCombo - Sql Table Called Stock With Two Fields Called StockID And StockCode
Jun 5, 2011I have an sql table called Stock with two fields called StockID and StockCode. I want the user to select the stockcode from a combo which in turn populates the stockid for that item into a lable on my form. I have already populated the stockcode into the combo but dont know how to compelte the rest.
Imports System.Data.SqlClient
Public Class cbo2
Private Sub cbo2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
[CODE]...
Access Other Data Fields From Combo Box Data Source?
Nov 4, 2009I have a combo box with a data source. This box shows one column of a table and allows me to select one item.Next, I have an ordinary text LABEL that I need to put text from another column of the item selected above.I tried to set the data binding field of the label, but this grabs only the first row or data and shows the selected column. That is nice, but I can not figure out how to update the selected selected ROW when the combo box item is changed.In this case the combo box lists a bunch of inventory parts. When I select a specific part, I need the change the text in a label to show the manufacturer. (like a sub-form). This same behavior will be used in several other places, but the relationships can cascade.
View 4 RepliesRefactoring A Module Into A Class: Changing Shared Fields To Instance Fields
Nov 14, 2011I'm currently refactoring an old Visual Basic DLL (VB.Net), which stores all of its data in one module called Globaldefinitions as public fields. There are about 200 fields, referenced thousands of times all around the code:
Public Module Globaldefinitons
Public a As Short
...
Public zz10 As Double
[Code]...
I need to change the module into a class with non-shared fields. This means, each and every of these thousands of references needs to reference the instance of that class:
globalDefinitionsInstance.a = 5
How do I go about this efficiently?
Regular expressions operating on the source fall flat. Refactoring tools like Re-Sharper or CodeRush don't seem to offer this functionality. Visual Studio 2010 cannot do it automatically either.
Can The Initialization Order Of Class Fields In .NET Be Influenced By References To Other Fields
Jun 19, 2011Class Foo
ReadOnly name As String
Public Sub New(name As String, dependentUpon As Foo)
Me.name = name
[code]....
The output of New Bar() is:
Dependent created. Dependent upon nothing.
Independent created. Dependent upon nothing.
It seems fields are initialized in the same order as they appear in the source code, which (a) leads to an unexpected result, and (b) seems a little puzzling, given that one is normally not permitted to read from uninitialized variables in .NET, yet that seems to be working fine above.I would've expected VB.NET to be smart enough to initialize referenced fields first, and only then those that reference it; i.e. I'd have liked to see this output instead:
Independent created. Dependent upon nothing.
Dependent created. Dependent upon Independent.
how to get VB.NET to behave like that instead, without simply having to swap the declaration order of dependent and independent inside class Bar?
Create Word Form Fields With Memo Fields From Access?
May 27, 2012I'm trying to create a table in Word using data from a table in Access. There are four fields in the access table that I need. 3 fields are text which I can populate the Word without any issues. However the fourth field is a memo with >255 characters.I'm struggling to come up with the proper code to allow me to populate the Word field with the memo data that has more than 255 characters. The code I have so far is listed below. But when it hits the memo field, it crashes on the line I marked with **. I know it's not text, but I've tried many different field types, but nothing has worked so far.[code]...
View 1 RepliesValidating Login Fields - Check The Username And Password Fields
Jan 14, 2012My intent is to have the code - on a button.click event - check the Username and Password fields and return an error depending on which is wrong. Or if both are wrong, return a different error message. I've set the username as parts and the password as parts (still learning how to use external authentication). [Code]
View 2 RepliesGridview Combine Autogenerated Fields And Template Fields
Aug 17, 2010I have several sqldatasources for my gridview. All of the columns are autogenerated. However they all have some consistent fields and I'd like to make those fields template fields so I can modify the edit template for them such as adding a drop down menu. Is this possible?
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