So I'm just trying to understand why someone would want to use the shorthand property instantiation
Public Property CarModel As String <-- property
As opposed to
Public CarModel As String <-- variable
Is there a VB.net equivalent to the C#:
public string FirstName { get; set; }
I know you can do
Public Property name() As String
Get
Return _name.ToString
[code].....
But I can't seem to google up an answer on a vb shorthand.
I have a custom control with a bindable property:-
Private _Value As Object
<Bindable(True), ... > _
Public Property Value() As Object
Get
[code]....
Also, here, I'm adding a handler to the DataBindings.CollectionChanged event.This is the second place that I retrieve the type:-
Private Sub DataBindings_CollectionChanged(ByVal sender As Object, ByVal e As System.ComponentModel.CollectionChangeEventArgs)
If e.Action = CollectionChangeAction.Add Then
Dim b As Binding = DirectCast(e.Element, Binding)
[code]....
I need the first place, because the BindingContextChanged event is not fired until some time after InitializeComponent.The second place is needed if the binding field is programatically changed.Am I handling the correct events here, or is there a cleaner way to do it?
Note: My GetValueType method uses the CurrencyManager.GetItemProperties....etc, to retrieve the type.
I'm having some very weird issues with interfaces right now.
I have a very simple setup. In one of my class, I have a Property implementing a Property from an Interface.
In my class it's like:
Private _oForm As IForm
Public Property Form As IForm Implements IContainer.Form
Set(value As IForm)
[Code]...
I have like dozens of interfaces like this working throughout my project and I can't believe this simple one can't work!
I am currently learning vb.net for my new job and I have mixed feelings over public fields. I see many arguments about them hurting the encapsulation. In python, the common practice is to keep things simple and use fields when they are enough. If we want to add logic later, we just refactor them into a property without breaking anything for the client code.In the codebase I am working with I see huge classes containing dozen of properties like:
[Code]...
I am getting a weird error when trying to run a certain part of my code.
The error is: Field or Property CharSet is Not Found
The Code Is:
<DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
Private Shared Function GetClassName(ByVal hWnd As IntPtr, ByVal lpClassName As StringBuilder, ByVal nMaxCount As Integer) As Integer
End Function
I have an 8 bit digital output board used for device controlling. Each external device needs one bit and is controlled by a different application.I have written a class library and the class DigitalOutputPort (VB 2010) that envelopes the driver that manages the 8 bit port. Each device application uses this class, creating its own instance.
In order to set a bit of the digital output port, I have to write a byte to that port: this byte is the bit mask for all 8 bits together: to set HIGH the bit number 0 - 1 - 2, I have to write 7 on the port, to set HIGH all 8 bits, I have to write 256, and so on...
All works fine when only ONE application uses the class. But if two applications want to set its own bit on that port, I get problems because I do not know the current value of all bits set by other applications (the driver has not such function) and, of course, I cannot change one bit without changing all the other (if I do not know the current bit mask)
Normally this looks like a typical case of sharing data between two application and my first idea was to write the current value of the port in a file on the disc, where all application can access and read it. But it seems to be too much heavy for this simple problem. Moreover it could also creates performance ans reliability problem.
Then I though about using a shared field (property) in the class. A shared field preserves its value between all instances of a class: but is it also true between instances from different applications? I cannot find more info about this last point, I have to make same test.
A third way would be that I create just only ONE instance of the class DigitalOutputPort, one for all applications.The first application that needs it, create the object, all other applications will used the already created object.I like more than other this way, but I do not know if and how it can be done.
I have a simple class that I trying to populate from an XML document. The XML file has an attribute called TrackingID in the root node which I would like to get as a property. For some reason, when I deseralize the class, the TrackingID is null. Everything else populates fine. I have tried various attributes on the TrackingID property with no luck.
[Code]...
I have made a front-end application in Visual Basic .NET that will store data entered by the user in a backend Access 2003 Database. The application has other functionality as well.If the user searchs for a previous record that has been stored in the Access Database, I query the Database (SELECT ... ) using an OLEDB Connection and then display the records on a Datagrid on my Form. Everything is working fine, however, the Column Headings of the Datagrid are the Field Names in my Database (FirstName, LastName,...) rather than Caption Values (First Name, Last Name,... )
I tried looking up the net, but most of the topics addressing a similar problems use DAO, and I understand that it is not completely supported in VB .NET. I am fairly new to VB .NET and I am not quite sure how to address the problem or where I am going wrong. I tried using FirstName.Caption but that gives a Runtime error (One or more parameters missing from the Sentence)
I have an Entity Data Model with two entities in it "Roles" and "Users". There is a navigation property from I have a EntityDataSource and a GridView. The EntityDataSource points to the Users entity and has an Include="Roles" parameter.I've added a BoundField in the GridView that points to RoleName, a property of the entity Roles. However, when I execute the code I get the above error.I have used very similar code successfully in another application. Any ideas why this isn't working?
Here is my EntityDataSource:
<asp:EntityDataSource ID="EntityDataSource1" runat="server"
ConnectionString="name=pbu_checklistEntities"
DefaultContainerName="pbu_checklistEntities" EnableDelete="True"
EnableFlattening="False" EnableUpdate="True" EntitySetName="Users" Include="Role">
</asp:EntityDataSource>
And here is the BoundField:
<asp:BoundField DataField="RoleName" HeaderText="Role" SortExpression="RoleName" />
[code] I get this error Name of field or property being initialized in an object initializer must start with '.' How should I write this? Or is there an alternative way of doing this?
View 2 RepliesI've got a custom NumericEditor control that has a nullable Decimal property called Value. When I bind a data field to Value, I'd like to retrieve the underlying Type of the data that's bound, so that I can restrict the use of decimal places if the source field is an integral data type.I figure I'd have to do this in the BindingContextChanged event, but how do I get the Type of the data field from the binding itself? My Google-Fu is failing me at the moment.
In short, I'm looking for something like the GetValueType method mentioned in the following question: Simple databinding - How to handle bound field/property change. Winforms, .Net I imagine this method would also be handy if the Value property was an Object.
In VB.NET, what are the advantages of using the Property keyword rather than:[code]Coming from Java I tend to use this style rather than Property...End Property - is there any reason not to?
View 4 RepliesMy LINQ query is as follows
Dim Query = From t In New XPQuery(Of xUser)(Xpo.Session.DefaultSession)
.Where("Name=John").Select("new (Name as FirstName)")
Unfortunately i get the error No property or field 'John' exists in type 'xUser'.Of course no such property exists in my xUser class, but hot can i fix that?After reading within the DynamicLinq Class i found this function
Function FindPropertyOrField(ByVal type As Type, ByVal memberName As String, ByVal staticAccess As Boolean) As MemberInfo
Dim flags As BindingFlags = BindingFlags.Public Or BindingFlags.DeclaredOnly Or _
If(staticAccess, BindingFlags.Static, BindingFlags.Instance)[code]...
How can i edit my "faulty" query? What am i doing wrong here?
I needed to create an Access table programmatically an was able to by using Martin Xie's post but how can I set the Field1 - Field Property Index to Yes (No Duplicates)?
[code]...
Is there a way for implementers of an interface where a ReadOnly property is defined to make it a complete Read/Write Property ?
Imagine I define an interface to provide a ReadOnly Property (i.e., just a getter for a given value) :
Interface SomeInterface
'the interface only say that implementers must provide a value for reading
ReadOnly Property PublicProperty As String
End Interface
This means implementers must commit to providing a value. But I would like a given implementer to also allow setting that value. In my head, this would mean providing the Property's setter as part of the implementation, doing something like this :
Public Property PublicProperty As String Implements SomeInterface.PublicProperty
Get
Return _myProperty
[code]....
I searched on the forum / Internet for the solution how a PropetryInfo object (of a Public property) can reveal if it has a Private Protected Setter ... it was all in vain .... all help I found was about how to "Set" value of a public property having a Private Setter.I would like to know if I have a PropertyInfo object of a public property, how would I know if its Setter is Non Public?
I tried, in a exception handling block, where I did a GetValue of the PropertyInfo object and then called SetValue by setting the same value back... but to my surprise it worked well and didn error out.
[Code]...
I have written a .Net 4.0 Winforms Numeric Editor control (which inherits from TextBox), and I have added a Value property that is a nullable decimal type, as follows:
Public Class NumericEditor
Inherits TextBox
Private _value As Decimal? = Nothing
[code]....
how to get around this exception, particularly when I'm databinding a number field to a number property, and there should be no string conversion happening. (To further complicate things, I'm using a similar technique for another control where I databind a DateTime field to a nullable DateTime property, and that control works just fine.)
I have a class that exposes an auto implemented property Enabled
[Code]...
But If I had not use an auto implemented property and declared my own backing-field as follows this is accessible from the subclass: Private _Enabled as Boolean ---- EDIT ----
The abve line is incorrect - this is not possible, it was in fact Protected in the original code which allowed access from the sub class See @JonSkeet answer ---- EDIT Of course I can just access Enabled from the sub class to work around this but can someone explain why this is the behaviour?
I have used ADOX for create some fields in my database in access but the required property of this appended fields (columns) are set in "yes" but I want to be them "No" who knows how can I solve this problem
View 3 RepliesI'm having a few problems converting some code into VB.NET from C#. Most of the translating is done, but I am getting errors when I try to run my code, and I can't figure out what is causing them. Here is the Sub I translated.
Public Sub CreateWidget()
Dim blue As LCDColor
blue.Red = 0
blue.Green = 0
[code]....
The error I receive on this line ("vision.Widgets.CreateWidget(wg1)") reads "In order to evaluate an indexed property, the property must be qualified and the arguments must be explicitly supplied by the user."
start with I was given a program by a friend that was created in Excel 2003 with the help of Visual Basic Editor. He said he used Visual Basic 2003, which he is not 100% sure about. Anyways he used CurLine in the program and when I try to open it in Excel 2007 and then open the Visual Basic Editor and run the program I get the following error:Run-time error '-2147418113 (8000ffff)':Could not get the CurLine property. Unexpected call to method or property access.
View 2 RepliesI have a very simple class that holds a few public properties - ID, Text, Colour, etc. and a Boolean called 'SelectedItem'. Just like the Checked property on RadioButtons, only one item can have its SelectedItem property set to True within a particular group. Note: there will be several separate groups (lists), each allowed to have only one item with SelectedItem = True.
My first thought was that I would probably just have to handle everything outside of the class, setting SelectedItem to False for every other item in a particular list when another item was selected. But that seems rather inelegant to me. So I've been trying to think of how this might be done within the class. For example: could I perhaps have a private string property called say "GroupName" - set in the New sub when adding a new instance of the class - and then use a private shared method to set every item's SelectedItem property to False, provided the item has the same GroupName as the newly selected item? I would have a go at doing this but I have no idea how to enumerate every instance of a class from within that class, or whether that's even possible. Is it? Or is there another (better) way to achieve my goal? Here is a cut-down version of what I've got so far:
Public Class ResourceItem
Public ID As Integer
Public Text As String[code]....
As can be seen: instead of instantiating a new ResourceItem and passing that as an argument to the manager's Add procedure, I'm simply passing the details of the new item and the procedure is creating the item from those. I don't know whether this is a good or bad idea - please advise - but I've done it because I couldn't figure out how to make the SelectedItem property only writeable by the manager, so I wanted to avoid having directly accessible objects that could have their SelectedItem property set to True without it deselecting all the other items in the same group. Of course that still leaves the possibility of setting a variable to one of the manager's list items and setting it from there, so I would still like to know how I could prevent that, if possible.
UPDATE: I didn't use the code above in the end, deciding instead to go with Cyborgx37's solution - which seems to work perfectly well for me despite the warnings about best practice. I also realised I would need to use the same class in another scenario where multiple items could be selected, so it was easy to add a Boolean property to the manager to enable that.
Using the following code I get Identifier expected and Property access must assign property or use its value errors:
ViewState["SomeKeyValue"]
What is wrong with this code?
I have a dataview an i would like to show the count property in a text box.
i tryied the following
me.textbox1.DataBindings.add(new DataBindind("Text",DataView,"Count"))
But i have a exception.
I have a listbox binded to a list of objects. For each list item I wanted to have a rectangle whose fill color is determined by a few properties of the binded object. So I did the following:
Made sure INotifyPropertyChanged was implemented on my object.Created a class to expose the properties I am interested in as attached properties.Binded the properties of the object to the attached properties of the rectangle Created a style that uses triggers to set the rectangle fill based on attached properties.
This works, but only the first time the property of the object changes. After that, the attached properties do not seem to be receiving notification when the data object's property changes. I have double checked and my data object is raising the INotifyPropertyChanged event.
<Rectangle Style="{StaticResource RecordStateRectangleStyle}"
Width="10" Height="10" Stroke="Black"
local:RecordAttachment.RecordState="{Binding Path=RecordState}"
local:RecordAttachment.IsDeleted="{Binding Path=IsDeleted}" />
[code]....
I have a weird question and I honestly hope you understand what is happening here: I design my form (using VB.NET) and put on it a few textboxes, comboboxes and a listview. After the design, I want to adjust the TabIndexes for each control on the form. On the right-hand side of the interface is the property box.
I then select the 'TabIndex' property item and enter a number key (for instance 0) for that selected item. I then select the next textbox control and enter the next number (for instance 1) WITHOUT re-selecting the 'TabIndex' property item. As soon as I select the combobox or listview control, the currently selected property item jumps to 'Items' or 'Collections' and does NOT remain on the 'TabIndex' property item. Why is this happening? Everything worked fine and all of a sudden this starts happening. Should I reset the editor settings or how can I resolve this matter?
I have a listbox with several list items added. I want that as user click on an item, I should be able to show its property. This should change for different items. For example (hypothetical) : Listbox has numbers 1 - 10. Now when I select 1 I should be able to set property - Name, Lastname, Colour, Age.
When I select 2 I should be able to set - Age, Hair Colour (clr shows), Weight, Date. When I select 3 then - City (combo box drop down), Country, Age only. This way value changes for diff items. One way is to put them in property grid and show them. Though this looks nice but adding/removing items in that is not easy. You need to have a class that refer that to prop grid. Do I have to code for each classes for all values in listbox or is there an easier way to manage items in property grid. If you think prop grid is not the right tool for such an activity then can you suggest something else.
I receive a System.Data.SqlClient.SqlException in the following code: Specifically Incorrect syntax near ' In order to evaluate an indexed property, the property must be qualified and the arguments must be explicitly supplied by the user. The exception detail in its entirety is shown below the code.
[Code]...
on a Windows Form, an object myObject is bound to myObjectDataBindingSource like this:myObjectDataBindingSource .DatSource = myObject on the form, i have a check box bound to the property: chkProp1 for example of the object: myObjectDataBindingSource In the code when the checkbox is clicked, I need to go in code and change another text property of the object txtProper2 for example like this:
Private Sub chkProp1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles chkProp1.CheckedChanged
[code].....