In my main method I have this and a few more hard coded ones:
Dim dropdownItems = New ListItemCollection
dropdownItems.Add(New ListItem With {.Value = ""})
Then in that method I call another method like this which I call in my main method. If it is not returning null then I want to do this:
Dim items = Me.GetMoreStuff()
If items IsNot Nothing Then
dropdownItems.AddRange(items)
End Id
And that other method that I am calling it something like this:
Private Function GetMoreStuff() As ListItemCollection
' some more of those items.
Return dropdownItems
End Function
But I am getting a Cannot Covert Type error. Why?
Based on the documentation, AddRange takes an array of ListItem, not a ListItemCollection. You'll have to convert your ListItemCollection to an array or just return an array (or a list) from GetMoreStuff.
You can also convert using
items.Cast(Of ListItem).ToArray()
Related
Summary:I want to create objects in a for each loop.
I have a class - Dashboard, which has some properties - length, height, etc.
This info is contained within an XML document, but my class' properties is only a small subset of the information in the XML.
I have created a Collection of XElement, and I can iterate over these, but how do I create my object on each iteration of the loop?
Dim Col_DashBoards As IEnumerable(Of XElement) = From XDashboard In XDocument.Load(filename).Descendants("dashboard")
For Each XDashboard In Col_DashBoards
'PseudoCode
Dim Xdashboard.Name as New DashboardClassObject
Xdashboard.Name.Height = XDashboard.Element("Height").value
...
Next
If I have understood your question correctly, you wish to create a new object based on a subset of data from within an XML document?
The below is a function that will generate a new DashboardClassObject for every matching node and populate that object. A list of type DashboardclassObject is returned.
Public Function GenerateDashBoardFromXML(filename as string) As List(Of DashboardClassObject)
Dim dashboardList As List(Of DashboardClassObject) = New List(Of DashboardClassObject)()
Dim Col_DashBoards As IEnumerable(Of XElement) = From XDashboard In XDocument.Load(filename)?.Descendants("dashboard")
For Each XDashboard In Col_DashBoards
Dim dashboard As DashboardClassObject = New DashboardClassObject () With {
.Name = XDashboard.Element("Height")?.value
}
dashboardList.Add(dashboard)
Next
return dashboardList
End Function
It should be noted that Null checking is used here. The below is only populated if the matching element is found. Null coalescing operator is also an option here.
.Name = XDashboard.Element("Height")?.value
How do i loop through this class once I add items via this method. Just I am quite new to generic lists so was wonding if someone could point me in right direction in datatables im used to doing the following:
For Each thisentry In dt.rows
Next
What do I use in collections
Calling Code
Calling this in my delciarations of main class
Dim infoNoProductAvail As List(Of infoProductsNotFound) = New List(Of infoProductsNotFound)()
this is how i am adding the files but I have checked in the routine and the count for the list is at 2 products
If medProductInfo.SKU.SKUID = 0 Then
infoNoProductAvail.Add(New infoProductsNotFound(thisenty2.Item("EAN13").ToString(), True))
End If
this is the class itselfs
Public Class infoProductsNotFound
Public Sub New(tbcode As String, notfound As Boolean)
Me.tagbarcode = tbcode
Me.notfound = notfound
End Sub
Private tagbarcode As String = String.Empty
Private notfound As Boolean
Public Property tbcode() As String
Get
Return tagbarcode
End Get
Set(ByVal value As String)
tagbarcode = value
End Set
End Property
Public Property isNotFound() As Boolean
Get
Return notfound
End Get
Set(ByVal value As Boolean)
notfound = value
End Set
End Property
End Class
Tried
I tried using the following
Function BuildExceptionsForEmail()
Dim retval As String = ""
Dim cnt As Int32 = 0
retval = "The following products are not avialable" & vbCrLf
For Each info As infoProductsNotFound In infoNoProductAvail
retval &= info.tbcode
cnt &= 1
Next
Return retval
but for some reason at this point my info noproductAvail is blank even though in the routine above its sitting at count of 2 what gives?
First I'd shrink that declaration a bit:
Dim infoNoProductAvail As New List(Of infoProductsNotFound)
Next, to iterate there are several options. First (and what you're likely most used to):
For Each info as infoProductsNotFound in infoNoProductAvail
If info.tbCode = "xyz" Then
DoSomething(info)
End If
Next
Or you might want to use lambda expressions (if you're using .Net 3.5 and above I think - might be .Net 4):
infoNoProductAvail.ForEach (Function(item) DoSomething(item))
Remember that generics are strongly typed (unlike the old VB collections) so no need to cast whatever comes out: you can access properties and methods directly.
If infoNoProductAvail(3).isNotFound Then
'Do something
End If
(Not that that is a great example, but you get the idea).
The For Each syntax is the same. It works the same way for all IEnumerable objects. The only "trick" to it is to make sure that your iterator variable is of the correct type, and also to make sure that you are iterating through the correct object.
In the case of the DataTable, you are iterating over it's Rows property. That property is an IEnumerable object containing a list of DataRow objects. Therefore, to iterate through it with For Each, you must use an iterator variable of type DataRow (or one of its base classes, such as Object).
To iterate through a generic List(Of T), the IEnumerable object is the List object itself. You don't need to go to one of it's properties. The type of the iterator needs to match the type of the items in the list:
For Each i As infoProductsNotFound In infoNoProductAvail
' ...
Next
Or:
Dim i As infoProductsNotFound
For Each i In infoNoProductAvail
' ...
Next
Or:
For Each i As Object In infoNoProductAvail
' ...
Next
Etc.
how can I pass the items of listbox to richtextbox?. I have multiple items and I want it to display in the richtextbox. this items is like a receipt. it display the items along with its amount.
This is just a way to do it, using LINQ:
Dim Items As String() =
From s As String In ListBox1.Items
RichTextBox1.Text = String.Join(Environment.NewLine, Items)
One of the problems doing this with a listbox, is that listboxes store the items as objects and uses the ToString method of each object to display a representation of that object.
Something like this should work:
RichTextBox1.Lines = (From o In ListBox1.Items
Let ostr = o.ToString
Select ostr).ToArray
This way if you use objects that can't be implicitly cast as string it will still work. Or, if you use custom objects all that's required is a ToString override in the class.
I'm just curious if it's possible to gather a list of data and put it into a list or array and easily pull them out using some variable(like a tag property on controls) on each item in the list rather than using the index. An example would be if i have many controls on a form and would like to populate the values using the list but instead of having to cross check a lot of different indicies(would take a lot of time) i could just assign the label to some 'tag like' variable for the list item.
Is this possible?
Lists in .NET, such as the List(Of T) class, only support storing one object per item. However, the beauty of them is, you can store any type of object that you want. If you need to store metadata with your data, simply create a new class that holds all the data for each item. For instance:
Public Class MyControlData
Public Property LabelText As String
Public Property Value As String
End Class
Then you can add the items to the list like this:
Dim dataList As New List(Of MyControlData)()
Dim item As New MyControlData()
item.LabelText = "Name"
item.Value = "Bob"
dataList.Add(item)
And you can read the data from the list like this:
For Each i As MyControlData in dataList
Label1.Text = i.LabelText
TextBox1.Text = i.Value
Next
I would use a Dictionary object so you can use a key to reference your data easily.
You can use LINQ:
Dim myTagControls = From ctrl In Me.Controls.Cast(Of Control)()
Where "your-tag".Equals(ctrl.Tag)
For Each ctrl In myTagControls
Console.WriteLine("Tag:{0} Name:{1}", ctrl.Tag, ctrl.Name)
Next
if i generate a label dynamically i can change the text as followed, variable is a string:
Form.Controls(variable).text = "test"
I now have a sub that will create some and will get some information out of arrays. I have a lot of them. I only want the function for tat specific array. I do not want a case or if. Thats why i was wondering if i can use a variable in the array variable. Sounds strange, here is what i mean:
Public TestArray() as String
Public Sub BuildStructure(ByVal Shelf As String)
Dim XMax as Integer
XMax = TestArray.GetLength(1)
End Sub
But instead of TestArray beeing hardcoded i want it to be replaced with Shelf. So whatever gets send into the sub will change the array that i'm using.
Is that possible some how or is the way totally wrong?
Thanks
You can use an arraylist object that you can easily add and remove items from at runtime. Here's the MSDN page: http://msdn.microsoft.com/en-us/library/7x4b0a97.aspx
Public TestArray As New ArrayList
Public Sub BuildStructure(ByVal Shelf As String)
TestArray.Add(Shelf)
End Sub
If you need an array, you can always call the .ToArray method on the ArrayList