How To Quickly Transform A List(Of Object) Into A List(Of "Object.field")
May 29, 2012
Suppose I have a list of Cat.
Public Class Cat
Public Property id As Guid
Public Property name As String
Public Property race As catRace
End Class
How can I quickly transform this List(Of Cat) into a List(Of Guid) using the id property?
I could do :
Dim newList As List(Of Guid)
For each item in catList
newList.Add(item.id)
Next
But I think there must be a way to do this faster (1 LOC). I just can't find how.
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Sep 3, 2009
After reading all the examples for list of T exists and Find and find first, none show how to handle multi-property objects. Below is bare bones example maybe someone could flesh out to show how this should be done.
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim DatePriceList As New List(Of DateAndPrice)
DatePriceList.Add(New DateAndPrice(Date.Parse("1/1/2000"), 10.12))
DatePriceList.Add(New DateAndPrice(Date.Parse("1/2/2000"), 11.12))
[Code]...
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Sep 6, 2011
Limited to using v2.0 of .Net framework (we use VB.net) due to environmental constraints on our servers.I've got an ASP.net webpage which pulls data from a webservice that performs checks on user accounts in active directory. Operators can check multiple accounts at one time using the web interface. The webservice returns a list(of AccountCheck) objects which themselves contain single properties like username, email address, and List(of AccountError) objects which contain multiple properties.[code]What I want to do is using some kind of repeater, create multiple panels or divs which contain labels showing the username, email etc, and a gridview which has the accounterror list bound to it to show all the errors. The users could be checking 2, 5, 7 accounts at once, and is dynamic.
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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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Oct 16, 2009
Does link text mean I have to return a concrete implementation? Even though I am using svcutil with the /r that includes my entites(where IMyInterface is defined). I get no errors but it changes all List(of IMyInterface) to list(of Object) and I cannot deserialize it on the client
Error: list(of object) cannot be converted to list(of IMyInterface).
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Feb 1, 2012
In VB.net, when I retrieve a value from a list do I get a copy of that value or a reference to it?
dim blah as someObject
dim listOfBlahs as list(of someObject)
listOfBlah.add(new someObject(1))
[Code]....
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Jun 15, 2011
I need to be able to add elements to a copy of mylist.testlist without modifying the global mylist object. (Which seems to be happening via the below code.)When I am working on x, which should be a totally separate object, mylist is getting modified as well. How can I fix this? I have worked with lists extensively and never seen this behavior before. I have tested and reproduced the problem in .NET 3.5 and .NET 4.0 on Win 7 Pro 32bit.
Source Code:
Public Class Form1
Public mylist As New test
Sub Main()
[code]....
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Jun 2, 2011
I would like to create list of child objects from list of parent object. Like If i have list of bookingroom which has one member room then i would like to create list of room from it.
eg. code:
Dim BookingRoomList As List(Of BookingRoom) = New List(Of BookingRoom)
Dim RoomList As List(Of Room) = New List(Of Room)
BookingRoomList = BookingRooms.FillGrid()
[Code]....
Is there any short cut method instead of iterating over for earch?
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Jun 15, 2012
I am having a problem when setting VB.NET list object to another.I create an instance on ReadLocations and than create an object of ReadLocation where then I loop through ReadLocations and set ReadLocation1 equal to rl. What happens is that if I then go and change ReadLocation1 to something else (assdfhsd) it will also change the ReadLocations index. I am really confused why it would be doing that unless it is "=" sign means referencing instead of actually setting the value. Please help as I am a C# developer but the program I am modifying is in VB.NET.[code]
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Dec 22, 2010
I have 2 classes
Public Class Shipper
Public Property ShipperID As Long
Public Property CreateDate As DateTime
[Code].....
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Nov 8, 2010
How to know if a List(Of T) contains any control object without using a loop ?This doesn't work
Dim lstObject As New List(Of Object)
lstObject.Add("STRING")
lstObject.Add(2)
[code].....
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Jul 29, 2010
I would like to ask what is the efficiency way the clean and dispose the object collected in the List (Of Object)?
Is that by calling the List.Clear() method will automatic clean all the object collected by it?
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Feb 11, 2011
I am able to populate an object and output everything. How do I remove say the name2 object?
la.Remove(Logins("name2")) doesn't seem to work.
Private Sub btnListArray_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnListArray.Click
[code]....
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Apr 3, 2012
I have a fonction that operates a list of base objects. But I have a list of derived objects. What is the most efficient way to transform it?
[Code]...
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Jun 5, 2012
I have a list(Of transaction) :
[Code]....
How can I transform it to a list(Of transactionShortened) :
[Code]....
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Nov 1, 2011
MVC 3 razor VB.NET project. I have resorted to manual building a list for a drop down box so I can insure certain values are available in the select list and also to control what the first item is in the list. The below is my code snippet for the part that is giving me problems..
[Code]...
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Apr 25, 2011
I have a class that has a property that I declare like this:
VB.NET
Private _DirectoryList As List(Of FileDirectoryInfo) ''' <summary> ''' Array of directories. ''' </summary> ''' <value>Object</value> ''' <returns>Directory array list</returns> ''' <remarks>N/A</remarks> Public Property Directory As List(Of FileDirectoryInfo) Get Return _DirectoryList End Get Set(ByVal value As List(Of FileDirectoryInfo)) _DirectoryList = value End Set End Property
[Code]...
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Aug 13, 2011
I'm trying to code a class of RandomNumber. One of the class methods needs to populate a "List (Of RandomNumber)" ... which was passed as a parameter to the method ... with 10 random numbers between 1 and 50. DEAD SIMPLE :)
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Dec 19, 2011
I've created A list of object "emails" which contains the "email" object which has 3 parameters (String Address, String Subject, String Body)I then want to add to the list by creating more instances of "email". However, I've tried so many different ways and it's having none of it.
Public Class Test
Public emails As List(Of Email)
[code].....
If I click button1 I get the error "Object reference not set to an instance of an object".
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Feb 22, 2011
I using Microsoft.Office.Interop.Excel I get returned a 2D array of type object[,] which contains double for elements. Note that the index lower bound is 1 instead of the default 0, but I can deal with that easily. How can nicely convert the array into double[,] using .NET 3.5. (by nicely I mean concise, or compact).
[Code]...
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May 23, 2010
I have a number of custom objects of type X. X has a number of parameters and must be unique in the collection. (I created my own equals method based on the custom parameters to examine this) In each object of type x, I have a list of objects y.I want to add/remove/modify easily an object y. To write the add method, it would be something like add(objTypeX, objTypeY)I would check or the collections already has a objTypeX.If so: i would add the objTypeY to the already existing objTypeX else: i would create objTypeX and add objTypeY to this object. [code] Which collections should I use? I tried with hashset but i can get a specific object out of the list, without run down the list till I find that object.
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Aug 3, 2010
I'm trying to convert an object, that is a list of something, to that list, but I'm having problems figuring out exactly how to do that. I have created the following code:
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim a As New List(Of String)
[Code]....
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Sep 2, 2010
I created a simple (for now) custom object:
VB
Public Class Form1
Dim AllPartFiles As List(Of Part)
[code]....
As I search a folder for files, it returns FilePath as a string for each file in the folder, then assigns a new Part.FullFilePath to the current returned FilePath, then add the Part to AllPartFiles list. So I can retrieve each Part from AllPartFiles later. But everything I try doesnt work.I know below is wrong, but might show what Im trying to do:
VB
Dim Files() As String
Files = System.IO.Directory.GetFiles(RootFolder, "*.ipt")
Dim k As String
[code]....
Create a New Part, change its values, and then add it to AllPartFiles list for later, then repeat?
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Jul 18, 2012
I have a question on searching a List(Of CLass). I am not sure how it is labeled List<OF T> or List(Of Class) However you label it here is the Class EXT.[code]As you can see from the SearchForExtension Sub I have 4 different ways to search for the extension. The index is used to select the searched for row in the DataGridView.
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Feb 26, 2010
I'm trying to use the Contains method but it refuses to recognise a like for like object. Both lists can contain the same objects at the time the statement is called at run-time and the if statement still executes at each iteration of the for loop.
[Code]...
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Mar 2, 2011
I am trying to sort a list of classes, and I need the classes with a subclass that isnot nothing first in the list. I thought the following would work but it doesnt.ListOfClasses.Sort(Function(x, y) If(x.SubClass IsNot Nothing, 1, 0)
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Sep 30, 2011
I'm working on a small game that is based on a map of grid squares.I have a class (clsGrid) that stores a few properties for each grid square.The grid square objects are organized into a list(of clsGrid).A loop and stream reader are successfully reading properties from a text file, putting the properties into grid objects, and adding the grid objects to a my list of grids. When retrieving a grid from the list of grids, I'm getting unusual results. Regardless of the index I give the list, I always seem to get the last indexed grid in the list.The debugger seems to suggest that the right numbers are being read into the stream reader and they are being added to gridHolder. However, the message box at the end will always show me the LAST grid.id, regardless of the index I give it.
'A subroutine that generates a map (list of grids)
Sub GenerateMap()
Dim reader As StreamReader = File.OpenText("map1.txt")[code]....
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Nov 6, 2011
I have created a list of another class and loaded the list with data. using breakpoints I can see that the data is loading and visible in my form page. However, when I attempt to access the list using a For Each loop, I get an error saying that "Value of type Customer can not be converted to Integer"I am trying to follow examples from tutorials on accessing list elements, but they are never lists of objects, so I am not sure what I am doing wrong.
My class that I have made a list of:
Public Class Customer
Private m_firstName As String
[code]......
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Mar 28, 2010
I have some code that adds items to a List(of Object).
Here's my original code
Dim BeaconStoryList as New List(Of My.StoryType)
Dim BeaconStory as New My.StoryType
Dim NewStories() as New Foriegn.StoryType = GetStories
[Code]....
But as soon as the code assigned "Chicken" to BeaconStory.Title, then BeaconStoryList(0).Title would also change to "Chicken".
With my second version of the code this did not happen.
It's as though it was placing pointers into the elements of the array rather than values. If that is the case, however, then why does my second version of the code work - I'm still passing in the same thing - aren't I?
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Aug 5, 2011
I am not sure what I'm doing wrong, but I need some guidance from people smarter than me...
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