VB.NET Forms ListBox doesn't display DataSource - vb.net

I'm trying to link my ListBox to an ObservableCollection.
Here's my class for defining mods:
Public Class TroveMod
Private m_FileName As String
Private m_Enabled As Boolean
Public Property FileName() As String
Get
Return m_FileName
End Get
Set(value As String)
m_FileName = value
End Set
End Property
Public Property Enabled() As Boolean
Get
Return m_Enabled
End Get
Set(value As Boolean)
m_Enabled = value
End Set
End Property
Public ReadOnly Property ModName()
Get
Return Path.GetFileNameWithoutExtension(FileName)
End Get
End Property
End Class
And this is the actual Property ModList:
Public Property ModList() As ObservableCollection(Of TroveMod)
Get
Return m_ModList
End Get
Set(value As ObservableCollection(Of TroveMod))
m_ModList = value
End Set
End Property
I add items using:
Private Sub AddMod(file__1 As String, enabled As Boolean)
If File.Exists(file__1) Then
ModList.Add(New TroveMod() With { _
.FileName = file__1, _
.Enabled = enabled _
})
End If
End Sub
Everytime I want to add something to this Collection using AddMod, it won't show off in my listbox :/ I added an ModListBindingSource to the ListBox and set the DisplayMember and ValueMember to ModName but it still won't work. I also got a status label, which says, that it successful added the mods to the collection but it simply won't show them in the ListBox. Did I miss something?

An ObservableCollection is not quite what you want - this would allow your code to see changes to the collection via events. For instance, if there were several actors adding items to the collection and you wanted to know that. In this case, since 'local' code is adding items, it is not needed.
It is also not clear how the collection is mapped to the ListBox as the DataSource. Try this:
Public Class Form...
Private myList As New BindingList(Of TroveMod)
Sub Form_Load(....
theListBox.DataSource = myList
theListBox.DisplayMember = "ModName"
Now, as you add things to the BindingList they will appear in theListBox. If an item changes though (e.g. the Name), that change will not show up without a little more work, but as these are file names that seems unlikely.
The form property is not needed unless an external class also needs access to the collection/BindingList; in that case, you probably do not want need a setter.

Related

Change the defaultValue of A custom control property

I created a number of custom controls but still struggling mastering the interface.
For uniformity besides creating custom proerties I also want to change some base properties of the custom control I tried following code
Protected Overrides Sub OnControlAdded(e As ControlEventArgs)
Me.AutoCompleteMode = AutoCompleteMode.Suggest
Me.AutoCompleteSource = AutoCompleteSource.ListItems
MyBase.OnControlAdded(e)
End Sub
That however does not work when I drop the custom control on a form, I suppose the solution lies with adding the attribute and overriding the property.
I found an answer to this for C# but did not succeed to understand/translate it for vb.net
Since those properties are not overridable, try using the Shadows modifier instead:
Public Class MyComboBox
Inherits ComboBox
Public Sub New()
Me.AutoCompleteMode = AutoCompleteMode.Suggest
Me.AutoCompleteSource = AutoCompleteSource.ListItems
End Sub
<DefaultValue(AutoCompleteMode.Suggest)> _
Public Shadows Property AutoCompleteMode As AutoCompleteMode
Get
Return MyBase.AutoCompleteMode
End Get
Set(value As AutoCompleteMode)
MyBase.AutoCompleteMode = value
End Set
End Property
<DefaultValue(AutoCompleteSource.ListItems)> _
Public Shadows Property AutoCompleteSource As AutoCompleteSource
Get
Return MyBase.AutoCompleteSource
End Get
Set(value As AutoCompleteSource)
MyBase.AutoCompleteSource = value
End Set
End Property
End Class
Please note though, the DefaultValue attribute probably doesn't do what you think it does: it doesn't actually set a default value of that property. All it is used for is to tell the PropertyGrid what the default value for the property is, and if it matches it, it won't make it bold in the PropertyGrid view and it won't serialize the value in the designer file.

Working with bindinglist

I have a datagridview and a bindinglist. They work together pretty ok, but I want to make the properties appear in the rows, not on the column. Is there any way to achieve that ?
My code for anyone who is interested.
Public Class Form1
Dim listaBindingSource As New BindingList(Of pessoa)
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim b1 As New pessoa()
listaBindingSource.Add(b1)
dgv.DataSource = listaBindingSource
End Sub
End Class
Public Class pessoa
Dim sells_Month1 As String
Public Sub New() 'ByVal nome_fora As String)
sells_Month1 = "0"
End Sub
Property vendas1 As String
Get
Return sells_Month1
End Get
Set(value As String)
sells_Month1 = value
End Set
End Property
The other properties are vendas2, vendas3.. and are the same as this one.
Edit:
I´m kind of lost here. What I want is to make the values of the properties of my objects appear on some kind of data visualizer. When I add new objects on the list, they appear on this data visualizer and when I change the values of the cells there, the values of the properties change. Anyone has a good sugestion ? Apparentely dgv is not the way to go.
Thanks,
Ricardo S.
I want to make the properties appear in the rows´ headers, not on
the column.
I'm afraid this is not possible, there is no built-in solution for that in DataGidView. You can display the properties in columns only.
To control the text displayed in the column header, try to set the DisplayName attribut:
<System.ComponentModel.DisplayName("DisplayedText")>
Property vendas1 As String
Get
Return sells_Month1
End Get
Set(value As String)
sells_Month1 = value
End Set
End Property
Or if you import System.ComponentModel namespace.
<DisplayName("DisplayedText")>
Property vendas1 As String
Get
Return sells_Month1
End Get
Set(value As String)
sells_Month1 = value
End Set
End Property

Custom CollectionEditor never triggers a property's "set" method

I am trying to implement a way of persisting a collection in a custom settings class. I have successfully created the settings class (inheriting ApplicationSettingsBase) and can save properties using the built-in editors on a PropertyGrid, but my custom implementation of a property grid for collections doesn't persist any of the values I add. Here's my code:
Imports System.Configuration
Imports System.ComponentModel
Imports System.Drawing.Design
Imports System.ComponentModel.Design
Public Class CustomSettings
Inherits ApplicationSettingsBase
<UserScopedSetting()> _
<DefaultSettingValue("White")> _
Public Property BackgroundColor() As Color
Get
BackgroundColor = Me("BackgroundColor")
End Get
Set(ByVal value As Color)
Me("BackgroundColor") = value
End Set
End Property
<UserScopedSetting()> _
<DesignerSerializationVisibility(DesignerSerializationVisibility.Content)> _
<Editor(GetType(CustomStringCollectionEditor), GetType(UITypeEditor))> _
Public Property EmailAddresses() As Collection
Get
EmailAddresses = Me("EmailAddresses")
End Get
Set(ByVal value As Collection)
Me("EmailAddresses") = value
End Set
End Property
End Class
Public Class CustomStringCollectionEditor
Inherits CollectionEditor
Public Sub New()
MyBase.New(GetType(Collection))
End Sub
Protected Overrides Function CreateInstance(ByVal itemType As System.Type) As Object
Return String.Empty
End Function
Protected Overrides Function CreateCollectionItemType() As System.Type
Return GetType(String)
End Function
End Class
I set a breakpoint on the Set methods for both the BackgroundColor property and the EmailAddresses property. The BackgroundColor property works as it should - it breaks on the Set statement and stores the property correctly. But when I close the custom CollectionEditor dialog, the EmailAddresses "Set" method is never called. How can I get my custom editor to actually save the property once it's done being edited?
I think I fixed it (with help from this question). I added an override to the EditValue function in my custom editor. Here is the code:
Public Overrides Function EditValue(ByVal context As System.ComponentModel.ITypeDescriptorContext, ByVal provider As System.IServiceProvider, ByVal value As Object) As Object
Dim result As Object = MyBase.EditValue(context, provider, value)
DirectCast(context.Instance, CustomSettings).EmailAddresses = DirectCast(result, List(Of String))
Return result
End Function
I also moved from a collection to a list - I read somewhere that was a safer way to go. I also added a constructor to my CustomSettings class that set the EmailAddresses property to a new List(Of String) if it was unset to begin with. I found that the first time it ran, I could edit the list and add items, but they wouldn't be persisted:
Public Sub New()
If Me("EmailAddresses") Is Nothing Then
Me("EmailAddresses") = New List(Of String)
End If
End Sub
And now it's all working like it should. But if this isn't the best way or there's an easier way to do it, please chime in.

Create a dropdown list of valid property values for a custom control

I've created a custom user control that has several properties. One specifies which database I want the control to access. I want to be able to present the user of the control a drop down from which he can select which database the control will interact with.
How do I get the dropdown to work? I can get default values, but have yet to figure out how to get the selectable list.
Any help is apprectiated.
Thanks.
Marshall
You just need to attach your own TypeConverter to your property. You will override the GetStandardValuesSupported and GetStandardValues methods (maybe GetStandardValuesExclusive too) to return the list of databases you want to show.
If you are new to the PropertyGrid and the TypeConverter, here is a document.
It turns out to be simpler than I thought.
I had an enumeration set up for the property, but was having trouble using it for the property type. Said it was unaccessable outside of the class.
Then I had a 'duh' moment and changed the enumeration from Friend to Public, and then I was able to use the enumeration as the property type. As a result the values from the enumeration are listed in a dropdown when I look at the values for that property of the controls.
Thanks to all that answered.
Marshall
I'm a little confused about your problem.
If your user control contains a DropDownList control, just inititalize somewhere in the user control.
The easiest way is in the Codebehind for the usercontrol, just do DropDownList.Items.Add() or whatever the syntax is for adding an item.
Here is the template I use to create a custom datasource for my comboboxes:
Private Class Listing
Private _List As New ArrayList
Public Sub Add(ByVal ItemNumber As Integer, ByVal ItemName As String)
_List.Add(New dataItem(ItemNumber, ItemName))
End Sub
Public ReadOnly Property List() As ArrayList
Get
Return _List
End Get
End Property
End Class
Private Class dataItem
Private _ItemNumber As Integer
Private _ItemName As String
Public Sub New(ByVal intItemNumber As Integer, ByVal strItemName As String)
Me._ItemNumber = intItemNumber
Me._ItemName = strItemName
End Sub
Public ReadOnly Property ItemName() As String
Get
Return _ItemName
End Get
End Property
Public ReadOnly Property ItemNumber() As Integer
Get
Return _ItemNumber
End Get
End Property
Public ReadOnly Property DisplayValue() As String
Get
Return CStr(Me._ItemNumber).Trim & " - " & _ItemName.Trim
End Get
End Property
Public Overrides Function ToString() As String
Return CStr(Me._ItemNumber).Trim & " - " & _ItemName.Trim
End Function
End Class
And this is how I load it:
ListBindSource = New Listing
Me.BindingSource.MoveFirst()
For Each Row As DataRowView In Me.BindingSource.List
Dim strName As String = String.Empty
Dim intPos As Integer = Me.BindingSource.Find("Number", Row("Number"))
If intPos > -1 Then
Me.BindingSource.Position = intPos
strName = Me.BindingSource.Current("Name")
End If
ListBindSource.Add(Row("Number"), strName)
Next
cboNumber.DataSource = ListBindSource.POList
cboNumber.DisplayMember = "DisplayValue"
cboNumber.ValueMember = "Number"
AddHandler cboNumber.SelectedIndexChanged, AddressOf _
cboNumber_SelectedIndexChanged
Hope this helps. One thing to keep in mind is that if cboNumber has a handler already assigned to the SelectedIndexchanged event, you will encounter problems. So don't create a default event.

Create Custom Control with reusable properties

This is similar to my last post but with a different purpose.
I have built a custom control, but when I set the properties for it... ALL instances of that control on my page grab the exact same property. I need to be able to set the property to "abc" for one instance of the control on my page, and then set the exact same proprty to "xyz" for a different instance of the control on the same page.
Can anyone shed any light?
Namespace CustomControl
Public Class mycontrol : Inherits Literal
Protected Overrides Sub CreateChildControls()
Dim value As String = "test"
If _doubleit = True Then
value = value & " test"
End If
MyBase.Text = value
MyBase.CreateChildControls()
End Sub
Private Shared _doubleit As Boolean = True
Public Shared Property doubleit() As Boolean
Get
Return _doubleit
End Get
Set(ByVal value As Boolean)
_doubleit = value
End Set
End Property
End Class
End Namespace
Remove the Shared from your variable and from your property declaration. Shared means exactly that what you don't want: All instances share the same value.
So, your code should look like this:
Private _doubleit As Boolean = True
Public Property doubleit() As Boolean
Get
Return _doubleit
End Get
Set(ByVal value As Boolean)
_doubleit = value
End Set
End Property