Imports System.Collections.Generic
Imports System.Globalization
Public Sub ListCountries(SourceCombo As System.Windows.Forms.ComboBox)
' Iterate the Framework Cultures...
For Each ci As CultureInfo In CultureInfo.GetCultures(CultureTypes.AllCultures)
Dim ri As RegionInfo
Try
ri = New RegionInfo(ci.Name)
Catch
'If a RegionInfo object could not be created don't use the CultureInfo for the country list.
Continue For
End Try
' Create new country dictionary entry.
Dim newKeyValuePair As New KeyValuePair(Of String, String)(ri.EnglishName, ri.ThreeLetterISORegionName)
' If the country is not already in the countryList add it...
If Not countryList.ContainsKey(ri.EnglishName) Then
countryList.Add(newKeyValuePair.Key, newKeyValuePair.Value)
SourceCombo.Items.Add(ri.EnglishName)
End If
Next
SourceCombo.Sorted = True
End Sub
I added three combo boxes to a form and called the above function three times for each combo boxes in the form load event.
like:
listcountries(ComboBox1)
listcountries(ComboBox2)
listcountries(ComboBox3)
but the first combobox only lists all countries and the other two are empty. please help me how to solve this.
im using vb.net 12 ultimate & windows 7
thank you
Why not return the country list object and bind the to each combobox using datasource?
Also items are added to comboxbox when countrylist doesnt contains that so need to clear countrylist. It should be comboxbox.Items.Contains()
The countryList dictionary is global to your class and it is initialized somewhere before calling this method. So the first call finds the dictionary empty and adds the infos both to the dictionary and the combo, but the second call (and the third one) find the dictionary already filled and thus doesn't add anything to the second (and third) combo
Without recreating the dictionary every time you call this method you could write
Dim countryList as SortedDictionary(Of string, String)
Public Sub ListCountries(SourceCombo As System.Windows.Forms.ComboBox)
If countryList Is Nothing Then
countryList = BuildCountryList()
End If
SourceCombo.DisplayMember = "Key"
SourceCombo.ValueMember = "Value"
SourceCombo.DataSource = New BindingSource(countryList, Nothing)
' No need to sort anything
End Sub
Public Function BuildCountryList() As SortedDictionary(Of String, String)
Dim temp = New SortedDictionary(Of String, String)
For Each ci As CultureInfo In CultureInfo.GetCultures(CultureTypes.AllCultures)
Dim ri As RegionInfo
Try
ri = New RegionInfo(ci.Name)
Catch
'If a RegionInfo object could not be created don't use the CultureInfo for the country list.
Continue For
End Try
' If the country is not already in the countryList add it...
If Not temp.ContainsKey(ri.EnglishName) Then
temp.Add(ri.EnglishName, ri.ThreeLetterISORegionName)
End If
Next
Return temp
End Function
Related
I created a datatable containing the list of notes for songs:
Private Table As New DataTable
Public Sub New()
With Table
.Columns.Add("Name")
.Columns.Add("NoteList")
.Rows.Add("GOT", GOT)
.Rows.Add("Yesterday", Yesterday)
End With
End Sub
GOT and Yesterday are lists of notes (notes is a class containing note, duration etc..)
On the form I then assign the datatable to a combobox:
ComboSongs.DisplayMember = Songs.DataTable.Columns(0).ColumnName
ComboSongs.ValueMember = Songs.DataTable.Columns(1).ColumnName
ComboSongs.DataSource = Songs.DataTable
I try to get the list of notes like this:
Dim songToPlay As List(Of Note) = CType(ComboSongs.SelectedValue, List(Of Note))
When I try to get the list I get the error:
System.InvalidCastException: 'Unable to cast object of type 'System.String' to type 'System.Collections.Generic.List`1[test.Note]'.'
Now I am unsure where I am getting it wrong. What would be the correct way to do this?
Your ValueMember is what is returned through the ComboBox.SelectedValue. So since you set the ValueMember like this
ComboSongs.ValueMember = Songs.DataTable.Columns(1).ColumnName
you only get the ColumnName. I assume that's a string and, well, the error message tells you it is one
... Unable to cast object of type 'System.String' ...
I guess that should be "NoteList", since that would be returned by Songs.DataTable.Columns(1).ColumnName
But this all doesn't make much sense, as I guess you are selecting a song there, either "Yesterday" or "GOT". At the point you're at it's so convoluted to return the DataTable rows, and index them. You will need to find the row by name and that is just too complicated when you could just create a class with strong names. I'll give you a class based solution but I'm not sure if you can make that change.
Private Class Song
Public Property Name As String
Public Property NoteList As List(Of Note)
End Class
Private Class Note
' your implementation
End Class
Dim songs As New List(Of Song)()
songs.Add(New Song() With {.Name = "GOT", .NoteList = New List(Of Note)})
songs.Add(New Song() With {.Name = "Yesterday", .NoteList = New List(Of Note)})
' need to populate those NoteLists first
ComboSongs.DisplayMember = "Name"
ComboSongs.DataSource = songs
Dim songToPlay = songs.SingleOrDefault(Function(s) s.Name = ComboSongs.SelectedValue)
Dim noteList = songToPlay.NoteList
i have a list(of custom class)
and i want to extract a list of all 'name' String, from it, through linq
I know how to do with a loop, but i need to get it with a linear, brief linq instruction.
i've checked this help
C# Extract list of fields from list of class
but i have problem in linq correct syntax
in particular because i would like to extract a New List(Of String)
Class Student
Sub New(ByVal NewName As String, ByVal NewAge As Integer)
Name = NewName
Age = NewAge
End Sub
Public Name As String
Public Age As Integer
End Class
Public Sub Main
Dim ClassRoom as New List(Of Student) From {New Student("Foo",33), New Student("Foo2",33), New Student("Foo3",22)}
Dim OneStudent as Student = ClassRoom(0)
Dim AllStudentsNames As New List(Of String) From {ClassRoom.Select(Function(x) x.Name <> OneStudent.Name).ToList}
End Sub
But something wrong...
Any help?
P.S. Since c# it's close to vb.Net, also c# helps are well welcome.
First, you don't need to create a new list From the one returned by the LINQ method. It's already in a new list at that point, so you can just set AllStudentsNames equal directly to what the ToList method returns.
Second, you are not selecting the name. You are selecting the result of the equality test to see if the names are different. In other words, when you say Select(Function(x) x.Name <> OneStudent.Name), that returns a list of booleans, where they true if the names are different and false if the names are the same. That's not what you want. You want the list of names, so you need to select the name.
Third, if you need to filter the list so that it only returns ones where the name is different, then you need to add a call to the Where method.
Dim AllStudentsNames As List(Of String) = ClassRoom.
Where(Function(x) x.Name <> OneStudent.Name).
Select(Function(x) x.Name).
ToList()
My project is in Visual Basic. I am trying to create a custom & savable "filter" for a DataGridView using several TextBoxes. Right now, any List(Of String) that is added to the Combo Box is displayed in the box as (Collection). I want my users to be able to select the one they created, so I would like the Lists to have a display name that can be selected in the Combo Box. Here is some of the code.
Dim savedFilter As New List(Of String)
savedFilter.Add(NameTextBox.Text)
savedFilter.Add(AgeTextBox.Text)
savedFilter.Add(NotesTextBox.Text)
ComboBoxSavedFilters.Items.Add(savedFilter)
Is it possible to add a display name for a List?
Or if you are lazy use buid-in generic class Tuple From MSDN.
Create collection of Tuple(Of String, List(Of String)) and use approach suggested by #Plutonix for binding collection to ComboBox
Dim savedFilter As New List(Of Tuple(Of String, List(Of String)))()
savedFilter.Add(
Tuple.Create("default",
New List From {"filter1", "filter2", "filter3"}))
savedFilter.Add(
Tuple.Create("Blue ones",
New List From {"filter4", "filter5"}))
savedFilter.Add(
Tuple.Create("Old ones",
New List From {NameTextBox.Text, AgeTextBox.Text, NotesTextBox.Text}))
With ComboBoxSavedFilters
.DisplayMember = "Item1" 'Name of first property in Tuple type
.ValueMember = "Item2" 'Name of second property in Tuple type -List
.DataSource = savedFilter
End With
Then SelectedValue will contain currently selected filter's collection,
which can be accessed like that
Dim filter As List(Of String) =
DirectCast(Me.ComboBoxSavedFilters.SelectedValue, List(Of String))
You could setup under My.Settings a StriingCollection
Initializing (you can omit the items added if so desired)
If My.Settings.Filters Is Nothing Then
My.Settings.Filters = New StringCollection() From {"One", "Two"}
End If
Setup items in a ComboBox
ComboBox1.Items.AddRange(My.Settings.Filters.Cast(Of String).ToArray)
Adding an item
My.Settings.Filters.Add(Now.ToShortDateString)
You can remove and clear items too.
Provide a Display Member for List(Of String)
Apparently, these are less a collection of filters than a collection of criteria or clauses for one Filter:
I condensed the code in the question, but there are 14 fields that can be filtered and there are multiple filters that can be applied on one field.
For the multiples per field, I am not sure I would want to store those individually, but keep the field criteria together. So, if you want to apply a name to these, a class would not only do that but could help manage the filter elements:
Public Class SuperFilter
Public Property Name As String
Public Property Elements As SortedList
Public ReadOnly Property FilterText As String
Get
Return GetFilterText()
End Get
End Property
Public Sub New(n As String)
Name = n
Elements = New SortedList
End Sub
Public Sub AddItem(filter As String)
Elements.Add(Elements.Count, filter)
End Sub
Public Sub InsetAt(index As Int32, filter As String)
Elements.Add(index, filter)
End Sub
Private Function GetFilterText() As String
Dim els(Elements.Count - 1) As String
Elements.Values.CopyTo(els, 0)
Return String.Join(" ", els)
End Function
Public Overrides Function ToString() As String
Return String.Format("{0} ({1})", Name, Elements.Count.ToString)
End Function
End Class
You would need to add methods and properties like Remove and Count but this should be enough to demonstrate. I am not sure about the SortedList, a Dictionary using the field name might be better, but something to control the order seems worthwhile. I am also unsure I would expose the Elements collection - managing it might be better left to the class.
Hopefully, the Combo displaying a set of these (as opposed to the filter elements/clauses) is the goal.
Private filters As New List(Of SuperFilter)
Add filter items to the list:
Dim item As New SuperFilter("Default")
item.AddItem("Id = 7")
filters.Add(item)
item = New SuperFilter("Blue Ones")
item.AddItem("Color = Blue")
filters.Add(item)
item = New SuperFilter("Complex")
item.AddItem("[Name] like %Bob% OR [Name] like %Alice%")
item.AddItem("AND Color = 'Blue'")
item.AddItem("AND Active=True")
item.AddItem("AND AccessRequired < 3")
item.AddItem("AND DateAdded > #2/11/2010#")
item.AddItem("AND CreatedBy = 'ziggy'")
filters.Add(item)
cbo1.DataSource = filters
cbo1.DisplayMember = "Name"
cbo1.ValueMember = "FilterText"
The value member could be the Elements - the collection of filter clauses, or it could be the query text. The GetFilterText method joins them together for you as part of what a filter manager class could/should:
For n As Int32 = 0 To filters.Count - 1
Console.WriteLine("Name: {0} Count: {1}{2}Text:{3}", filters(n).Name,
filters(n).Elements.Count,
Environment.NewLine, filters(n).FilterText)
Next
Result:
Name: Default Count: 1
Text:Id = 7
Name: Blue Ones Count: 1
Text:Color = Blue
Name: Complex Count: 6
Text:[Name] like %Bob% OR [Name] like %Alice% AND Color = 'Blue' AND Active=True AND AccessRequired < 3 AND DateAdded > #2/11/2010# AND CreatedBy = 'ziggy'
If you use "Elements" as the ValueMember you will get back the collection.
The combo displays the Name for the user. On the right, a label displays the ValueMember in this case, it is the FilterText or joined Elements. As I said, you could get back the actual collection as the SelectedValue instead, but that is available as part of SelectedItem.
If savable means beyond the life of the application instance, that is another question, but these are very easily serialized.
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.
I'm working on VB in college and am running into a snag with one of my assignments. Can someone help? I'm aiming to try to take the following dictionary code:
Public Class Inventory
Public ItemInventory As New Dictionary(Of String, Item)
Public Function iItem(ByVal key As String) As Item
Return ItemInventory(key)
End Function
Public Sub addItem(ByVal item As String, ByVal Desc As String, ByVal DRate As Double, ByVal WRate As Double, _
ByVal MRate As Double, ByVal Quantity As Integer)
With ItemInventory
.Add(item, New Item(item, Desc, DRate, WRate, MRate, Quantity))
End With
End Sub
Public Sub removeItem(ByVal item As String)
With ItemInventory
.Remove(item)
End With
End Sub
Public Function returnKeys() As String()
Dim Keys() As String
With ItemInventory
Keys = .Keys.ToList.ToArray
End With
Return Keys
End Function
End Class
Not pretty, I know, but it gets the job done, that's all I aim to do. Now a bit of this also has to do with displaying a dictionary item in the program, which I'm also having issues with, however, I'd like to take this one step at a time, so we'll get to that later, if possible.
As per writing, this is my current code for reading and writing:
Imports System.IO
Public Class InventoryFile
Public Sub RFile(ByVal FPath As String, ByRef dInventory As Inventory)
Dim infile As StreamReader = File.OpenText(FPath)
Dim entireLine As String = infile.ReadLine()
Dim fields() As String = entireLine.Split(","c)
While infile.EndOfStream
Dim dItem As New Item
dItem.ID = fields(0)
dItem.Description = fields(1)
dItem.Daily = fields(2)
dItem.Weekly = fields(3)
dItem.Monthly = fields(4)
dItem.Quantity = fields(5)
'AddItem
dInventory.addItem(dItem.ID, dItem.Description, dItem.Daily, dItem.Weekly, _
dItem.Monthly, dItem.Quantity)
End While
End Sub
Public Sub WFile(ByVal FPath As String, ByRef dInventory As Inventory)
Dim outfile As StreamWriter = File.CreateText(FPath)
For Each Item As KeyValuePair(Of String, Item) In dInventory.ItemInventory
Next
End Sub
End Class
I hope that posted right. Now, reading in, as far as I understand, works just fine, in terms of a file going into a dictionary, however 'WFile', my StreamWriter, is what's got me stumped. Can someone help me with that? Likewise, its supposed to close and write to the file upon closing, and my only code for the close button is the Me.Close() command. How would I write a trigger to make the program write to the file? Know that the main form code, and my 'InventoryFile' are both separate classes, so this has to be done by referencing the other classes in question
Try this to write each dictionary key/value pair on a single line in the file:
Dim fs As FileStream
' Open the stream and write to it.
fs = File.OpenWrite(FPath)
For Each Item As KeyValuePair(Of String, Item) In dInventory.ItemInventory
fs.Write("{0}:{1}", Item.Key, Item.Value)
Next
UPDATE:
Since Item is both the variable used in the loop and the name of a class, change it to another name like singleItem and then pull out the other pieces of information from the Value portion of the key/value pair, because the Value is actually an Item class object, like this:
Dim fs As FileStream
' Open the stream and write to it.
fs = File.OpenWrite(FPath)
For Each singleItem As KeyValuePair(Of String, Item) In dInventory.ItemInventory
fs.Write("{0}:{1}:{2}:{3}:{4}:{5}:{6}", singleItem.Key, singleItem.Value.ID, singleItem.Value.Description, singleItem.Value.Daily, singleItem.Value.Weekly, singleItem.Value.Monthly, singleItem.Value.Quantity)
Next
In order to create the format your RFile procedure can read you need something like this:
For Each kvp As KeyValuePair(Of String, Item) In dInventory.ItemInventory
' using Karl's compact approach, but add commas
' since your Read expects them
outfile.Write("{0},{1},{2},{3},{4}...", kvp.Key, kvp.Value.ID, _
kvp.Value.Description, ... kvp.Value.Quantity.Tostring)
' the Value part of the fvp is another class, right? `Value.XXX` should drill
' into it to get to the members
Next
outfile.flush
outfile.close ' look into 'Using...'
Thats NOT how I would do it, look into serialization for a less fragile way to read/write the data. It is basically meant for just this sort of thing: save class data for later, and it is not that hard to use.
as for hooking it up, the button click would just call Inventory.WFile