Why below code has error in VB.net 2008?Dim Object1 As New Class1Object1.SetId = If(rbSet.Checked = True, Convert.ToInt32(txtSetId.Text.Trim()), DBNull.Value)What I'm trying is to set a property of an object by a condition.
View 1 RepliesI'm using a loop condition to check if there is null value in the columns, then remove it.
-Original author
[STart:]
For i As Integer = counter To dt1.Columns.Count - 1
For x As Integer = 0 To dt1.Rows.Count - 1
if some condition then
something = true
[Code]...
Sometimes it runs correctly and sometimes even though when i becomes greater than (dt.columns.count - 1), it still executes the for loop and throws an error that there is no column with that index. I must be missing something here but I'm not able to debug the issue.
I'm implementing a State Machine in WF 4.0. In some transitions, I have added a condition where I check that some variables have the expected values. The variables are enums and booleans, and everything is fine.
However, now I tried to evaluate when a property is null. I have and argument in my workflow, let's say, 'MyArgument'. In a transition, I try to put a condition like 'MyArgument.MyProperty = Nothing'. I never developed in VB.NET, I don't know if I'm missing something here...
VS2010 gives the following error: "Error 4 Compiler error(s) encountered processing expression "MyArg.MyProp = Nothing".
Operator '=' is not defined for types 'XXXX' and 'XXXX'
The type names are exactly the same, and I have debugged VS2010 to ensure that my assembly is not loaded from 2 different locations.
How can I check if the property is null or not?
BTW, I'm using VS2010 SP 1, with .NET Platform Update 1 installed, on W7 64 bits.
In on a section of my book about classes and properties. In this example, the author is attempting to show how you can validate a value passed to the property before setting the property. Looks like so far in this book, a couple of things have slipped past the editor, and I think this might be another one...Here's the example:
[Code]...
How do I set a null value for an optional DateTime parameter in a constructor?
I'm using the following constructor below and I want the optional parameter admissionDate to be a null DateTime. Setting it to Nothing actually gives it a value (something like #12:00:00 #).
Public Sub New(ByVal obj1 as Object, Optional ByVal admissionDate As DateTime = System.Data.SqlTypes.SqlDateTime.Null)
I have a databound ComboBox on my form. Is there any way that I can make the first field blank.
I can do this with a DropDownList in the HTML part of .Net but is there a way to do it for a ComboBox?
is there any trick (because I can't think of anything else ! ) to massively set all of the properties , of a user defined class , to their null values ? You see , I have a class called Apartment and it has a lot of properties (it only has properties , no methods or events , if that's important) and those properties are either strings , doubles or integers . I want each time I create a new instance of that class (a new apartment , that is) to automatically set those properties to their null values . That is all of the strings to be equal to "" and all of the numbers to be equal to 0 . Back in VB6 I could rely on VB6 to do this automatically , but now in VB .NET , whenever I create a new instance of a class , all the properties start with the value = Nothing . I know I can define every property in the class module like that : Public MyVariable As String = "" but I'd like to keep them as they are and set their null values directly whenever a new object of that class is created .
View 8 RepliesIm writing an app which connects to a SQL Server database, via datasources / datatable.When Im looking at my .xsd I can see DataTables containing DataColumns. Each DataColumn has a 'NullValue' property which defaults to '(Throw exception)'.Because I have nulls in my tables I have gone through the fields and set all System.String fields to NullValue = 'Empty', System.int32 field to NullValue = 0.
View 1 RepliesI have a databound DataGridView, and I'd like to keep one column in front, with a slightly smaller width than the default. The grid's AutoSizeColumnsMode property is set to Fill so that the columns fill out the entire grid. This makes the first column equally large as all others, which is why I need to set its width manually. The smaller column is the first one with the checkboxes. I have two grids that I need to do this with, and for some reason it works just fine with the first grid, but gives a null reference error on the second grid...
Here's the code for the first grid (working fine):
vb.net
Public Sub UpdateTodoGrid()
' Load todo items
todoGrid.DataSource = _TodoManager.LoadAll()
' Set backcolor
For Each row As DataGridViewRow In todoGrid.Rows
[Code] .....
As you can see, the code is exactly the same (except for not setting the BackColor of each row and not using the ReadOnly property*). When I run this code, it gives me a null reference error ("Object reference not set to an instance of an object.") on the line where I set the column's Width. Obviously 'col' is not Nothing (otherwise it would have errored before that line), and there's nothing else there that could be Nothing... I assume that something happens internally in the grid when you set the width of a column, and that there is a null reference there, but obviously I have no control over that.
The grid's are absolutely the same, as the second grid is just a 'copy' (meaning I copy/pasted it in the designer) of the first. So all their properties are equal. I thought maybe the ReadOnly properties were the problem, but I tried putting them in in the same way and the issue did not go away... The first grid is not ReadOnly (because the checkboxes need to be editable), but all rows except the first are, while the second grid is completely ReadOnly.
'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?
I have the following property in a class:
[Code]....
The problem is that when I try to set the property like this: myClass.Language = "English" The property is set to "English" and not to "<![CDATA[English]]>" which is what I want. What is the reason for that and how can I fix it? When placing a break point on End Set and use the Watch window to inspect the value of _Language after setting the property to "English" it remains "English" and doesn't change.
Given a simple class like this:
Public Class clsOB
Implements System.ComponentModel.INotifyPropertyChanged
Private _Frequency As Double
Private _Value As Double
Public Event PropertyChanged(ByVal sender As Object, ByVal e As
[Code] .....
And then I'd like to do something like this:
Dim
o As
New
clsOB(50, 30)
o = 31
I am converting a 1.1 .NET web app to 3.5, and I've run into a bit of a jam.
One web control has a Property that sets the page title label on that web control.
End Property
When a page with the web control was loaded before, it would set the Property to a given string, like in ucHeader.PageTitle = "This is a string." Now, if I don't remove the lblPageTitle.Text = Value, I get a NullReference Exception.
I'm new to classes. In my Who wants to be a Millionaire application, I have a Lifeline class and I create three instances of it - FF, PAF and ATA (50/50, Phone a Friend and Ask the Audience). Something I do with a lifeline is put a cross over its logo, hence the need for a centrepoint property, which marks the centre of the cross on a form.
Public Class Lifeline
Private ptCentrePoint As Point
Public Property CentrePoint() As Point
Get
CentrePoint = ptCentrePoint
[Code] .....
What happens is that at the "Call Form2.DrawCross(Form2.CentrePoint)" line, the tooltip shows that the FF object's centrepoint property isn't set (as I thought it would be by " FF.CentrePoint = tmpPoint").
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?
[Code] Now the problem is that after i put this user-control in a form, I have to set a value for the Handled file. Otherwise it gives me a value cannot be null exception. Is there a way that i can set code that would execute in the case of the value being null? [Code]
View 14 RepliesI have this simple code,
Protected Sub grdSearch_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles grdSearch.SelectedIndexChanged
TimeOff.Where = "UserName=""" & grdSearch.SelectedValue & """"
End Sub
Doing so causes this error, 'UserName' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly. Near simple identifier, line 6, column 1.
The datasource works fine before the where property is set.Update: I found the issue but I still don't get it.Adding it. in the where clause solves the issue. Like this,
TimeOff.Where = "it.UserName=""" & grdSearch.SelectedValue & """"
I am using a user control using vb.net. It include the program to retrieve the values from database while giving the paramers. When I set the property from my main program i am getting an error "Invalid attempt to call Read when reader is closed." When i gone to the online help i got the message as follows "System.InvalidOperationException (.NET Framework 4)The exception that is thrown when a method call is invalid for the object's current state. InvalidOperationException is used in cases when the failure to invoke a method is caused by reasons other than invalid arguments. For example, InvalidOperationException is thrown by IEnumerator.MoveNext if objects of a collection are modified after the enumerator is created, or ResourceSet.GetString if the resource set is closed before the method call is made. If the method invocation failure is due to invalid arguments, then ArgumentException or one of its derived classes, ArgumentNullException or ArgumentOutOfRangeException, should be thrown instead.[code]
View 1 RepliesI am programatically creating instance of usercontrol as shown below
[code]...
I have two public properties in my usercontorl like clerkName and RespName. How can I set those values in the above code. Intellisense is not showing ClerkName and respName Properties.
i want to set autocomplete textbox, but if multiline property of textbox is true, i can't do it.
View 6 RepliesI'm reading in a configuration file which is simply a txt file that configures my Com port and sets some directories. It's basically for the end user to set the interface. I want to give the user the ability to change backcolor properties on my NumbericUpDown property. So when I read in the Config.txt file the end user can change coloring on the General Form. In this case the NumbericUpDown. How to assign a variable for color from my string (from my txt file) that I read in.
View 5 RepliesIm currently debugging my application to found out why it's running a bit slow, when I put breakpoint where i populate one of the application combobox it's run fast but after i populate it and when I'm trying to set the its selectedindex to zero the program halt for about 2 second.. this is the line where the program get stuck for 2 seconds:
[code]...
I am creating a customised version of the ListView control and there are several of the properties that a ListView has that I would like to be set to a different value to the ListView default when a user goes to use my user control.
From what I've found there seems to be a number of people suggesting just set them in the constructor, but to the best of my knowledge that would just mean that the user would not be able to change the properties in the PropertyGrid in the VS IDE.I assume this is probably something extremely simple that I have overlooked.
I have a single form that I would like to move across the screen with my VB program. Of course it's simple to set the location X and Y property for compile time using the properties tab, but I want the form to move as the program runschanging the coordinates within a for-next loop.I can easily get the X and Y coordinates of the form within my program by using X = me.location where X has been dimmed as type point.console.writeline(X) will appear as {X=20, Y=40}. for example
View 2 Replies.From = New MailAddress("Me@MySite.com", "Big Mike")This does not;
Dim AddressFrom As String = "Me@MySite.com"
Dim FromDisplayName As String = "Big Mike"
.From = New MailAddress(AddressFrom , FromDisplayName)
I receive the error; The specified string is not in the form required for an e-mail address.I would REALLY like to use variables here so that I can read these two pieces of data from My.Settings. I've been searching for the answer for hours and I'm stumped.
Can someone clarify if there is ever a need for the below?
When setting a textbox "Visible" property to False is there any reason why I should also set the "Enabled" property to false.
I have a lambda function that I can assign to a field and pass it to a sub routine, but cannot assign to a property. My field is defined as follows:
Public Delegate Sub SubDelegate()
Private pDeleteFunction As Func(Of BookCaseRow, SubDelegate)
[code].....
I have a Javascript function for my select box, but after I included runat="server" to it, the script debugger highlights on this line below:
' for (i = 0; i < sourceTo.options.length; i++) { ' and says:
SCRIPT5007: Unable to get value of the property 'length': object is null or undefined
I included it because I wanted to loop through it in code behind and perform some other stuffs?
Code:
<select multiple size="8" style="width: 135px" runat="server" id="outletFromBox">
<option value="JP">Jurong Point</option>
<option value="IMM">IMM</option>
[code]...
Trying to set a Combo Box RowSource to a field in a table that contains the choices separated by semi colons. Have tried both a query and a DLookup but it results in displaying the full contents of the table field, e.g. "10;12;14;16" rather than giving me the usual selection list
View 2 RepliesVS 2008, vb.net, Win7 development machine. I've developed a Windows application with several different forms, and am using the My.Settings feature. This is the first time that I have used this feature. For each form, I have set the form's property binding 'location' property to an entry in 'settings' of My Project settings page of the VS 2008 development environment. The settings are set to user scope.
1.) Do I need to add any code to my application to make the settings work, or is it sufficient that I have the "Save My.Settings on shutdown" set to true?
2.) When I create my setup to install the application, what settings file (app.config?) do I install to the user's machine, and what folder should it be installed to?