Determine Type Of Object In A Collection?
Oct 28, 2009
I can't figure out how to determine the type of an object in a collection. I want to do a For Each ... Next loop over the items in the DropDownItems collection of a ToolStripMenuItem. For those items that are ToolStripMenuItems themselves I want to take some kind of action. (The collection can contain other types of items, such as ToolStripSeparators). So I need to say something like: If Typeof(item) = ToolStripMenuItem Then .
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Oct 9, 2009
I have a small piece of code that iterates through the controls collection on a panel (below) Everything works fine until I want to focus on a control that doesn't support the selectall method i.e. a datetimepicker. Is there any way of determining the type of control and not call the selectall method when the type is datetimepicker. All my other controls support it so that's the only one I need to exclude.
[code]...
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Sep 7, 2010
I am customizing a DataGridView control. The DataGridView is supposed to be bound to a collection of some type (be it a List(Of T) or ArrayList or whatever), and the idea is that one can easily determine (at design-time in this case) which properties of the type have to be shown in the grid and which column header name they should get. One can do this using an attribute. For example, if I have a class Person with Name, Age and HairColor and I don't want to show the HairColor property, and want to show the Name property as 'Person', I would use:
vb.net
Public Class Person
<Grid.GridOptions(displayName:="Person", visible:=True)> _
Public Property Name As String
[code]....
I do this during run-time by simply looping through the properties of the bound type (in this case Person), retrieving the GridOptions attribute (if any) and checking the values provided. This works just fine except for one thing: I'm not really sure how to determine the type in the databound collection...
At the moment, I cast the DataSource property to an IList and retrieve the type of the first instance in that list (if any). If there isn't a first instance (the list is empty) then I don't know how to get the type... Often I know that it will be impossible to know the type. If someone is binding an ArrayList for example, then it's impossible to know what kind of items he's going to put in that ArrayList. Even the normal DataGridView cannot show any columns when databound to an empty ArrayList. However, the framework's DataGridView does show the columns when bound to, for example, an empty List(Of Person), or a Person array.
I'm pretty sure that casting the DataSource to an IList is not the correct way as all information about the type of items in that list is then lost. But I'm not sure what else to cast it to... ITypedList? IBindingList? I even considered List(Of T) because that's all I am going to be using, but besides the fact that the grid would then obviously only work for a List(Of T) I still don't know how to do this... I don't know 'T' so I can't cast it to a List(Of T)...
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May 19, 2009
I am still developing this function, but here is what I am intending it to do. This function will accept an Object, then try to determine its type. There are a specific set of types I am looking for: Integer, Boolean, Date, String. What I have so far is pretty privative, but it seems to be working so far:
Private Function DataType(ByVal entry As Object) As ValueType
Try
If IsNumeric(entry) Then
[Code].....
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Nov 25, 2011
Heres my sub:
Dim onThisTable as String ="Name"
Private Sub skill_mouseHover(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles button1.MouseHover, button2.MouseHover, panel1.MouseHover, panel2.MouseHover, pbox1.MouseHover
[Code]....
Now I wish to give onThisTable a different value depending what the user pass over (panel or a pbox or a button) but I cant find what is the correct way to compare what type it is ...
Private Sub skill_mouseHover(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles button1.MouseHover, button2.MouseHover, panel1.MouseHover, panel2.MouseHover, pbox1.MouseHover
[Code]....
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Jul 3, 2010
I am using VB .Net for this, so I don't have access to var or this would be a simple matter.Right now my query is as follows
[code]...
So I used this query in LinqPad to help me determine what the object would look like. I got back a IOrderQueryable(Of RSError) which then contained a IGrouping(Of String, RSError) for each grouped collection of objects returned by the query.However I ended up with the current object type of errors as IOrderedQueryable(Of IGrouping(Of String, RSError)) because of the cast error I am getting in VS.
[code]...
I'm not sure how to get rid of the VB$AnonymousType_1 Part of the returned object.Am I even on the right track here or am I missing something completely?
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Jan 12, 2011
I'm deserializing an object and in certain cases it works fine, however in others it fails. The exception is essentially meaningless to me, but there has to be a way to figure out where exactly it failed so i redirect my debugging.
[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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May 7, 2009
This error makes no sense to me[code]...
Unable to cast object of type 'DynamicTreeNode' to type 'DynamicTreeNode'.
I have an inherited TreeView with an inherited class called DynamicTreeNode inside it. I am trying to loop through the DynamicTreeNodes in the TreeView.Nodes property which is causing this error.
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Jan 25, 2011
For I = 0 To 10
If Items.Count = 0 Then Exit For
Dim T As New Thread(AddressOf Thread)
T.Start(New Object() {"Test", "Test"})
[code]....
When I put same code in empty project it works.
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Jul 5, 2010
I've got a piece of code in a project (MyProject) that contains early bound object from a referenced assembly (We'll call it CommonAssembly):
Dim myObject As CommonAssembly.MyEarlyBoundType
now I have another assembly that is dynamically loaded because it is not present in all projects:
Dim myLateBoundObject As Object = AppDomain.CurrentDomain.CreateInstanceAndUnwrap("Utils", "Utils.MyLateBoundType")
MyLateBoundType derives from CommonAssembly.MyEarlyBoundType, and I want to cast myObject to myLateBoundObject and then programmatically invoke the additional
[Code].....
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Apr 5, 2009
i always get this error when i tried to update my table: Unable to cast object of type 'System.Object[]' to type 'System.String[]'.
i only want to update STATUS, ENDTIME, and PRICE
the data type of each field are:
STATUS = nvarchar
ENDTIME = smalldatetime
PRICE = money
[Code]....
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Dec 16, 2011
I am trying to make it so when I use Me.Controls("Timer1") for example I can access specific commands for a timer such as Stop() Start(), I tried CType() and typed in "Timer" as the type but it says the control type can't be converted to the "Timer" type.
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Nov 5, 2011
Public Shared Function IsType(ctrl As Control, ByVal thisType As ??????) As Boolean Return (TypeOf ctrl Is thisType) I need a function that I can call, for example, to determine if a control is type RichTextbox.dim z as Boolean= IsType(txtBox1, RichTextBox) I ned to determine if a control is a given type (i.e., not always RichTextBox). I don't know what Type to make thisType. Can this be done?Actually I simpified the problem but if the above is answered I can write the function
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Apr 28, 2012
I want to scan a directory and see what files are NOT bmp image files. As the file extension can lie I need to interrogate the file itself. I found some code here [url]...?ID=112 that does exactly this however it was written for VB5 and is 13 years out of date! I tried compiling it however VB 2010 baulked and I don't have the expertise to make it work.
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Jul 31, 2009
How can I programatically determine if a file with a certain extension (XLS, for example) is really an Excel file and not a VBS file, for example, that has the XLS extension?
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Dec 12, 2009
I need to determine the type of a WinForms control in a collection.
[Code]...
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May 17, 2010
how do you determine cell type of a column?
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Oct 14, 2010
I need to check a value within the registry. The application (Cisco VPN) is a 32bit app so uses Wow6432Node when installed on 64bit operating systems.What would be the best method of selecting which string to use? Checking the OS for x64, attempting to read one and then the other if the first fails? Or is there a better method?
Dim keyName64 As String = "HKEY_LOCAL_MACHINESoftwareWow6432NodeCisco SystemsVPN Client"
Dim keyName32 As String = "HKEY_LOCAL_MACHINESoftwareCisco SystemsVPN Client"
Using .net 4.0 framework?:
Dim registryKey As RegistryKey
If Environment.Is64BitOperatingSystem = True Then
registryKey = registryKey.OpenBaseKey(Microsoft.Win32.RegistryHive.LocalMachine, RegistryView.Registry64)
Else
registryKey = RegistryKey.OpenBaseKey(Microsoft.Win32.RegistryHive.LocalMachine, RegistryView.Registry32)
End If
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Jul 31, 2011
I am converting a VB.Net application to C#. Everything else is going great. Except this bit. I have a function which builds menus,sub menus and seperators from a database. It can build a MenuStrip or a ContextMenuStrip which can then be assigned to a form.
This means that menus can be extensive and conpmex but managed outside the application, which I also use as part of my security access model. All menus are controlled from the database externally, it also means I can develop visual tools (Treeviews etc) to manage user menus. The application uses menus extensively which is by design.
Programmatically I want to assign an eventhandler to every item that isnt a dropdown or a seperator
In VB I would do this, (works perfectly)
[Code]...
"System.Windows.Forms.ToolStripItem' does not contain a definition for 'DropDownItems' and no extension method 'DropDownItems' accepting a first argument of type 'System.Windows.Forms.ToolStripItem' could be found (are you missing a using directive or an assembly reference?)"
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Mar 27, 2010
I have a class C(Of T). I want to determine if some given value has type C, regardless of what T is. For example, I might want to determine if a value is a strongly-typed list, regardless what type of items the list stores. I just need to know how to do it in VB.net. In Java the syntax is like this:
var result = obj instance of Gen2<?>;
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Mar 4, 2011
I'm looking for a similar "IsStructure" function. Is there some other way to determine if T is a structure but not an intrinsic type?
Public Shared Function MySub(Of TData)(ByVal t As TData) As TData
Dim IsClass As Boolean
IsClass = GetType(TData).IsClass
End Function
Note that using IsPrimitive and IsValueType on Nullable(Of Integer) and a Structure returns the same results, False and True, respectively.
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Aug 22, 2011
Public Class A
Private aa As Integer
Dim bb As Integer
Public cc As Integer
[code]....
what is the size of the object oA?and what if Class A and B contain methods?(I meant the size of object)what if inherited class B contains overridden methods?(size of object)what if inherited class B contains variables with same name as in Class A?(size of object)I need theoretical answer. Does those access specifiers Private,Dim,Public make any difference in allocating memory because of their different scopes?On what basis memory is allotted for a method? etc.
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Oct 22, 2010
The following works fine in c# (assuming value is an object):
if (value is DateTime)
What is the equivalent check for VB.NET?
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Mar 3, 2011
I have the following VB.NET function, for example:
Public Function MyFunction (Of TData) (ByVal InParam As Integer) As TData
End Sub
How do I, in a function, determine if TData is a NULLable Type?
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Mar 17, 2010
I have a dataset and want to know the data type of a specific column. The GetType returns datacolumn not string or integer etc.iggy!
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Sep 24, 2009
I'm interested in having a generic 'Try Catch' clause, with some case statements or if/than statements within the Catch part so that I can handle different error types differently. some way to get ex.Errorcode or ex.ErrorType that differentiates the different errors to a unique value.
How can this be done?
Try
'some code taht will throw an error'
Catch ex AS Exception
If ex.ErrorCode = 20 then
' Do something'
[Code].....
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Dec 14, 2006
I have the following VB.NET function, for example:Public Function MyFunction (Of TData) (ByVal InParam As Integer) As TDataEnd Sub
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Nov 14, 2010
I've created the following basic function to determine whether specific control type is currently loaded:
Private Function IsPreviewerTypeLoaded(Of T)() As Boolean
For Each previewer In LoadedPreviewers
If previewer.GetType().Equals(T) Then
[Code]....
I need to compare each control against the generic type supplied. Equals(T) fails to do the job, producing a compiler error. How to make it correctly?
UPDATE: is the following correct?
previewer.GetType().Equals(GetType(T))
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May 11, 2009
We would like to know whether there is any way to interrogate a Graphics object and determine whether it is to be used to print or to render to some other canvas. We're aware of an API call that can be used but would prefer to avoid that route if possible. There's also the possibility of simply passing a flag in with the Graphics object that is True from a PrintPage event handler and False from elsewhere, but that's not ideal either. We're looking for a managed property or method accessible via the Graphics class itself, but nothing's jumping out.
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