Cast/convert From List(Of DataRow) To List(Of String)?
May 22, 2012
I'm trying to solve a problem regarding types of list. First of all I have a stored procedure in my DB which does a select of a single column and I try to proceed it in my app in VB. By making a method function I declared a DataTable that loads through the SqlCommand(with the CloseConnection behavior). After that I publicly declared a List(Of String) which needs to be populated with the rows/items from the stored procedure that is on the way. Below is my snippet of the code:
Dim dt As New DataTable()
Try
If conn.State = ConnectionState.Open Then
[Code]....
It's LPrefix = collection.Cast(Of String)() where I get an exception error telling me that I can't really convert it. The old fashion way is to iterate with for/for each loop but that's not what I want for best use of performance especially if the list will have thousands of rows from a single column. So basically, I want to insert those items from that DataTable to the List(Of String) without For/For Each loop.
Running on VisualStudio2010 Ultimate, .NET FrameWork 4.0.
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Mar 25, 2010
I have the following code:
[code]...
The intention is to convert an IList of custom objects to a string equivalent comprising each element in the Ilist. Unfortunately I can't seem to find a way to get the underlying data of the custom object, and of course as in the above example, using object simply gives me a string of types definitions, rather than access to the underlying data.
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Apr 20, 2010
Function runs fine on the listbox until i use the btnUp_Lanemgr click event
throws an exception in function (below in bold) "Unable to cast object of type system.string to type namespace.myitem"
what i can do to make this work?
'Button moves selected listbox item up
Private Sub btnUp_Lanemgr_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnUp_Lanemgr.Click
[Code]....
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Apr 8, 2011
[Code]...
How can I convert a csv string into a list in vb.net?
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Jul 29, 2011
I want the Function to accept List(Of String), Array & String and similarly return List(Of String), Array & String respectively. The Function simply adds a string (month) to the input collection. I just want to use it for string, array and list with needing to think of conversions.
[Code]...
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May 10, 2009
Normally, I'd choose List<String> [or, in VB, List(Of String)] over StringCollection whenever possible: see also Best string container.
However, as it seems, generics — and hence, List<String> — are apparently not supported in VS 2008's settings designer. Therefore, if I want to use a list of strings in my user settings, I have to resort to using a StringCollection there.
Now as I don't want to see StringCollection throughout my code, I need to convert it to List<String>. How do I do this efficiently? Or, even better, am I mistaken and there is a way to use List<String> in settings designer?
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Feb 10, 2010
I am trying to Add the name of every folder in a directory to a combobox as a string to use in other code. Then I would like to truncate the last 3 characters off of the folder names.Example:
My main directory is C:Main
My sub folders are C:MainsubOne_bp
C:MainsubTwo_bp
C:MainsubThree_bp
I want a combo box with the following added durring run time.
subOne
subTwo
subThree
The following code will get me the folder names in the combo box, BUT it will not truncate the _bp off of the end and they are added as IO.DirectoryInfo that cannot be used as a string in other tasks.
Dim dir As String = "C:Main"
If (System.IO.Directory.Exists(dir)) Then
Dim di_dir As New IO.DirectoryInfo(dir)
[code]....
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Mar 6, 2012
I am looking for a way to convert my List(Of string) into an Object in vb. So in the end it would be the same as declaring Dim cArray() As Object = new Object. Can anyone point me to how i can achieve this? I cannot use the LINQ .ToArray as that creates a string array and this is not acceptable for my work. I need to pass this object into another one that has the parameter (aArray as Object).
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Apr 15, 2009
Whats the best way to convert a list(of string) to a string with the values seperated by ,
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May 26, 2012
y have this class
Private Class MyClass
Public Property propertyOne() as String
Public Property propertyTwo() as String
[code].....
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Oct 26, 2009
I want to convert a List (of Long) into a string array.
Reason: it's a list of database IDs and I want to make a comma delimited string to pass into a stored proc.I tried this:
Dim commaDelimitedList As String = String.Join(",", itemIDList.Cast(Of String)().ToArray)
but I'm clearly not using the Cast correctly since it throws an exception:
System.InvalidCastException: Unable to cast object of type 'System.Int64' to type 'System.String'..
Is there a way to get Cast working for this, or am I stuck with ConvertAll and a delegate function?
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Jan 27, 2012
I have a number of classes that all implement the same interface. e.g.
Public Class IncidentAsset
Implements IModelWithIdentity
Private _assetId As Int16
Private _otherAsset As String
Private _asset As Asset
[Code]...
Is there a better way of doing this in VB.NET using .NET 2.0?
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Dec 15, 2010
I got an object of List<List<string>>I need to bring this into a ist<string>I have no idea how to do this with LINQ.
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May 19, 2009
I am working in VB.net and have a Class, Foo, that implements an interface, IBar.I have a List of Foo's, but I need to pass a list of IBar's into a function, but I keep getting casting errors, even when I use DirectCast.My code is [code]MainWorks works, but it would be really annoying and inefficient to have to do that everywhere I want to call this function.
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Mar 13, 2009
I have a text box with a list of entries for example:
Reference 1
Reference 2
Reference 3
[Code]....
I plan to read the string back into a the textbox later using the split() method and assign each to string to an array.
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Aug 28, 2009
I'm using String.Join to attempt to turn an array list into a string that is comma separated, such as "1,2,3,4". I can't seem to get the syntax working.
Here's what I'm trying:
Dim aryTest As New ArrayList()
aryTest.Add("1")
aryTest.Add("2")
aryTest.Add("3")
[CODE]...
How can I go about doing this properly?
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Aug 5, 2011
i have a list of datarows. each row is having mutiple columns like userid,date,flag,etc.i want to sort the based on date. how can i do that ?
my code is:
Dim
listOfRows As
New List(Of
DataRow)()
[code]....
i want to sort the listOfRows in ascending order of date which is a column in a row?
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Oct 6, 2010
I'm sorting data in a dictionary there each key has a list with like 3 items.I want to get all the data from the dictionary to a datatable with the key and the list items on the same row.
all i manage to get is "key" System.Collections.Generic.List`1[System.Data.DataRow]
i'll guess somehow i will loop trough the list and add all elements to a string?[code]...
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May 25, 2010
1. How can I populate a List(of Integer) from datarow
2. How can I take only certain columns from datatable.select() and copy the data to datarow? So it's like this: datatable dt has columns ID,Name,age,address and DOB I want to take only the columns name, address and age where age>40 and put the result set into a datarow dr.
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Nov 11, 2011
Dim namelist As List(Of String) = New List(Of String)
namelist.Add("Hi")
namelist.Add("Hello")
[code].....
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Dec 5, 2011
We're working on a big ASP.NETVB.NET website project. I need to populate three dropdownlists. To last two are independent of the previous ones. The population data comes from an SQL Server. I'd have no problem doing this with code-behind with post back but we don't want any PostBacks so I started to develop this in AjaxjQuery.
[Code]...
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Nov 2, 2010
To be able to sort a dictionary by value I'm using this code:
Dim idCurrentJobs As IDictionary(Of String, Int32) = New Dictionary(Of String, Int32)
'The string in the dictionary represents a jobname and the integer is a counter for how many jobs im currently are running in the application'
idCurrentJobs.Add("JobName1", 2)
[code]....
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Apr 8, 2010
So I have the following
With Me.dgv
.AutoGenerateColumns = False
.DataSource = Info.PESList
[code]....
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Jun 10, 2010
how Inheriting List(of T) should work.It seems like what I have below should work but at runtime I get the error:[code..]
If I want to cast a List(of x) to the class xlist, how should I do that?[code...]
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Apr 19, 2011
I'm new to generics and am having some issues when using with interfaces.I'm developing with VS2008 - .NET 3.5 Ultimately, I'd like to create an interface that inherits the IList(Of T) interface and add a function definition to the derived interface that adds a new element of type T to the list and returns the index of the newly added item.
I have everything figured out but am stuck on a casting issue. If I execute the following line of code at runtime:CType(New clsObjectFactoryList(Of clsIDNamePair), ifObjectFactoryList(Of ifIDNamePair))
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Jun 9, 2009
the VB .net experts. I added the following code and I get an error as shown below.
[CODE]....
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Mar 29, 2012
I want to reorder a list of strings into a different list of strings. I am creating multiple loops to do this, however i was wondering if there was a better way to do this.
Dim values As New List(Of String)
For Each val As String In vals
If val.Contains("10") And val.Contains("Year 1") Then
[Code]....
There are going to be quite a lot of these loops to do what I want can anyone offer any help or a better way to go about doing this? Note that I want the values list to return 10,10,10,20,20,20 so that lines that have 10 should be added first and lines with 20 then afterwards.
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Jun 21, 2010
I am trying to delete a file(s) from a checked list box, when i click a button.
This is the code i have:
Dim item As IO.FileInfo
For Each item In CheckedListBox1.CheckedItems
Try
item.Delete()
Catch : End Try
Next item
But i get the error: Unable to cast object of type 'System.String' to type 'System.IO.FileInfo'.
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Nov 26, 2009
I have read many posts on this topic; among them and most recently .NET - Convert Generic Collection to Data Table. Unfortunately, all to no avail.
I have a generic collection of structures :
Private Structure MyStruct
Dim sState as String
Dim lValue as Long
Dim iLayer as Integer
End Structure
Dim LOStates As New List(Of MyStruct) I need to fill a DataTable with this list of structures but have no idea how to go about doing this. I am using vb.net in Visual Studio 2008.
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Dec 30, 2009
I have two List(Of String) both containing several hundred thousand results.
Private Function AddUniqueFiles(lNewFiles as List(Of String)) As outList(Of String)
Dim aCounter As Integer = 0
Dim files As New inList(Of String)
[Code]....
However the time it takes to do this comparison can be very long indeed - is there a better way of doing this type of comparison... All I am trying to do is add values from List2 in to List1 which are not already present in List1 - So in effect adding new Unique values found in List 2 in to List 1. I am only looking for performance improvements - nothing else.
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