Generic List Class Cast?
Jun 10, 2010how 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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Get Type Of Derived Generic List Class From List Item Method?
Mar 23, 2011Public Class notifierMain
Public Class Contacts
Inherits List(Of row)
Public Sub New()
[code]....
When I debug this winforms application I get curType = "notifier.notifierMain+Contacts+row" I want to the Validate function to know it is in MyContacts. How do I do this?
Unable To Cast Object Of Type .objectquery To Type Generic.list
Sep 12, 2011I have a question about ASP.Net, visual basic I have 2 LINQ query's, the first one works, the second one doesnt, produces a
"Unable to cast object of type 'System.Data.Objects.ObjectQuery'1[SelmaV2.Products]' to type 'System.Collections.Generic.List'1[System.String]'.
[Code]....
Overload Operator In Generic Class With Generic Interface Of Super Class And Inherit Class?
Jan 21, 2010I can do this without problem.
Class A
End Class
Class B : Inherit A
End Class
Dim Obj1 As A = New B
Add Custom Class To A Generic List?
May 10, 2010I created two classes. One class is StudentClass and the other is HomeroomClass. The HomeroomClass contains a readonly property as a generic list of the StudentClass. [code]...
View 6 RepliesSerialize A Class That Contains A Generic List?
Oct 7, 2010I am trying to serialize a class that contains a generic list, and I am finding it all works with the exception of the generic list property. That is to say the other properties are serialized fine and no error is produced.
I have in the past serialized an arraylist - but I thought it was possible to do a generic list in the same way.
Am I missing something or is it not possible to serialize/deserialize a generic list - I have read mixed comments on this..
The relevant parts of the class that gets serialized is defined as..
<XmlInclude(GetType(cConfigUser)), _
Serializable(), XmlRoot(ElementName:="Config")> _
Public Class cConfig
[Code].....
Passing A System.Collections.Generic.List To Another Class?
Jun 10, 2012I am trying to pass a System.Collections.Generic.List to another class. The collection is created in class2 and then passed into class1
[code]...
However I get a 'Null Reference Exception error' when I run the program. It seems f_str in the line 'For Each s As String In f_str' is null.
Unable To Cast Object Of Type 'System.Collections.Generic.List`1[System.Int32]' To Type 'crmWebService.ArrayOfInt'?
May 14, 2012I'm getting an error after sending a list to a web service.This is the code that is calling the web service:
Dim sProgramInterest As New List(Of Integer)
crmService.InsertProspectGetId(sProgramInterest.ToList)
But I'm getting this error.
[code].....
.net - Can A Generic Version Of A Derived Class Override A Base Method Using The Generic Type
Apr 13, 2012Consider:
Public MustInherit Class Column
Public ReadOnly Property ReturnSomethingUseful() As Object
Get
'return something useful
[code]....
But this gives the following error:
Public Overrides Function ParseValue(sValue As String) As Boolean'
cannot override 'Public Overridable Function ParseValue(sValue As String) As Object'
because they differ by their return types.
I accept that you can't do this, but I'd like to be able to preserve the semantics of what I'm. trying to do, which is to have an untyped version that deals with Object, but a typed version in derived classes that knows about the specific type T.
.net - Cast To Generic Type At Runtime?
Sep 9, 2010I'm in the process of creating a function which reflects over the properties in a class and adds them to this data structure I have. Some of the properties are generic types.So say we have DataType(Of T) that has a .Value property of type T:
Dim properties = GetType(MyType).GetFields(Reflection.BindingFlags.Public Or _
Reflection.BindingFlags.Instance)
For Each prop As fieldinfo In properties
Collection.Add(prop.Name,prop.GetValue(poco))
Next
In the collection.Add for primitive types (Integer, String, etc....) I just want to add the type... but in the case of generic I want to add the DataType(Of T).Value. I hope there is some work-around but I don't think there is a way because the type of T can not be determined at compile time right? Ideally DirectCast(prop.getvalue(poco), DataType(Of T)).Value would be possible. This is when you hoped even more dynamics appear than whats in .NET 4.0.
.net - Determining A Generic Type At Runtime In Non-Generic Class
Aug 14, 2010I have a Journal that records entries for different types: Journal(Of ParentT)
[Code]....
Construct A Generic Interface Class With Generic Functions
Nov 25, 2011I am trying to construct a generic interface class with generic functions. My goal was to use this to implement multiple worker classes for database interaction that have the same basic functionality. Each class will deal with different object for example, category, product or supplier but unless the the functions in the interface are generic that this won't work.This is the interface code that I have but I don't know if I have done it correctly. [code]
View 2 Replies.net - Call To Ctype Failing At Runtime For Cast From Int To Generic Type?
Feb 25, 2011I know about the existence of System.Nullable(Of T) Structure.I am trying to write a class to replace it: The Nullable(Of T) Class [VB code below]. But when I tested the Nullable(Of T) Class (See NullableOfTClassTest Class, Method Main) an exception occurs when using the CType operator to convert from System.Int32.Why does this happen at runtime, why isn't my Ctype operator method being called?
NOTE: code below reordered and reduced in order to hilite problem.
Namespace MyNamespace
Public NotInheritable Class NullableOfTClassTest
Private Sub New()
End Sub
[Code]...
.net - Strongly Cast A Reflection .GetValue() Object To A Generic DbSet?
Apr 10, 2012I'm using EF 4.3.1 in VS 2010 (.Net 4.0) to load a number of reference tables from a database in order to bind them to controls in a WinForms app.At form load, I'm pre-fetching the data so that it's stored locally, and I'm creating a dictionary of BindingSource objects that I can use to bind the local data to the controls.The intent is to minimize the impact of the EF's self validation on a cold query in order to load forms faster and improve UI responsiveness.I've written code to create and fetch the BindingSource object for a given DbSet collection as follows:
Private _dictBindings As New Dictionary(Of String, BindingSource)
Private Sub ValidateBinding(Of T As Class)(ByRef DbCollection As DbSet(Of T))
Dim strClassName As String = DbCollection.[GetType]().GetGenericArguments(0).Name
If Not _dictBindings.ContainsKey(strClassName) Then[code].....
However, I'd like to call ValidateBinding on all DbSet collections in the Model on startup, and I'd like to use reflection to iterate through the available collections in the context because we're currently loading 66 tables and could add more later.I've written the following code:
For Each propSet As PropertyInfo In Db.GetType.GetProperties(BindingFlags.Instance Or BindingFlags.Public).Where(Function(P) P.PropertyType.IsGenericType)
ValidateBinding(propSet.GetValue(Db, Nothing))
Next
but it won't work as propSet.GetValue() returns an Object instead of DbSet(of T).I also can't cast the object to a DbSet of the appropriate type, even though I know the type through reflection.I don't have access to the C# Dynamic type,and I know it's a pain to mix generics with reflection, but is there a solution for which I can pass in a reflected DbSet to my functions?Perhaps something using Method.Invoke?
.net - Creating A Generic List Of A Generic Type
Jun 30, 2011I am trying to create a list of a generic type in vb.net 2.0 framework.
This is the generic type definition:
Public Class GenericParamMap(Of T)
Public Sub New(ByVal pParamName As String, ByVal pPropValue As T)
mParamName = pParamName
[Code]....
The compiler does not allow a "T" in the method's parameter because it's not defined, but I'm not sure how or where to define it. I thought it was okay to have a generic method definition.
Cast/convert From List(Of DataRow) To List(Of String)?
May 22, 2012I'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.
Way To Implement IComparable (Of T) Or IComparer(Of T) If Class Is Not A Generic Class
Feb 19, 2010I am working on a general helper class to sort ListView SubItems. I wrote a base class that has much of the code I need. It includes a MustOverride for the Compare method so that the various inherited classes can implment their own comparisons based upon their type. For the value types, I end up with very similar code such as the following, where x and y are ListViewItems: Public Overloads Overrides Function Compare(ByVal x As Object, ByVal y As Object, ByVal sortColumnIndex As Integer, ByVal sortOrder As System.Windows.Forms.SortOrder) As Integer [code]
View 3 RepliesDetermine If Property Is Generic List<of T> Via Reflection And Loop List Items
Oct 1, 2009I'm looping all the properties in an object via reflection:
For Each p As PropertyInfo In values.[GetType]().GetProperties()
If p.CanRead Then
'Do stuff
End If
Next
how to determine whether the property in question is a generic List(Of T)? If it is I need to loop the list itself.
I've experimented with GetType and TypeOf but have not managed to get anything working.
To clarify, I want to keep this generic. I do not want to specify the type of T, I need to loop the list items and call the ToString method on each item. T could be one of a number of different types (application specific reference types). Is it possible to do this without specifying types?
(VB.NET 2005 with .Net 2.0)
.net - Returning A List Using Entity Framework, 'System.Collections.Generic.List Cannot Be Converted To '1-dimensional Array
May 3, 2012i have issue returning a list in a web method. here is the code
<WebMethod()> _
Public Function getTags(para_parents As String) As List(Of getTypeDetailsByParentName_Result)()
Dim context As New PPEntities
[code]....
the error is
Value of type 'System.Collections.Generic.List(Of SaftyonRoad.getTypeDetailsByParentName_Result)' cannot be converted to '1-dimensional array of System.Collections.Generic.List(Of SaftyonRoad.getTypeDetailsByParentName_Result)'
Pass Generic List To A Function That Has A Custom Defined List
Apr 7, 2011it seems always at this time I cant figure out how to do something maybe it has something to do with lunchtime.
Im having trouble using a method that is defined by an outside company
This is a link to their integration guide:
[URL]
This is their documentation for the class Im trying to use
OrderQueryWebService Class
This class is for SID in particular and is made for use with the notification methods. This is for the Order Query Web Service specifically, allowing clients to return the status of transactions for their merchant, whenever they want to.
Methods
/ <summary>
/ Pass through the variables required and receive a list of Transaction
objects showing transaction status
[Code].....
The MerchantCode, the MerchantUsername, the MerchantPassword are all good the List is a custom type called SetComHash.Transaction
Everytime I try adding a string to the list such as the transactionNumber and some other values it gives me a type error:
"Value of type string cannot be converted to 'SetcomHash.Transaction'
Cast Value Type To Nullable Enumeration Type In Generic Object If All Types Are Unknown At Write-time?
Dec 14, 2011I have a generic Class I'm using to hold information loaded from a database.I have a method which takes a DataRow as an argument, uses the object's known column name and extracts the data from the DataRow, such that:Dim loadData As T = CType(myDataRow("myColumnName"), T))works as my default assignment in most cases.Unfortunately, due to some horrifying design constraints, some of my columns may be null, and may also be taken from enumerations.This means that when <T> is Nullable(Of SomeEnumeration) the above code does not work because I can't cast 0 directly to SomeEnumeration.Zero.Is there some way to check whether <T> is Nullable(Of [Enum])? Or some way to write a method which allows Integers to be cast to Nullable(Of [Enum])?I feel like I'm forgetting something that would allow me to write one of the other of these, but my weak google-fu is turning up nothing.
EDIT: Okay, thanks to dasblinkenlight's answer below, I can detect when this circumstance is occurring, but what I need to do now is to take a type <T> which I know is Nullable(Of SomeClass), get a type reference to SomeClass and then create a new object of type Nullable(Of SomeClass) and assign that to LoadData.My problem was that I had a lot of difficulty in finding any function which would accept baseType as an actual Type.Parse accepted baseType as a parameter, I knew baseType was an [Enum] type because of dasblinkenlight's code, so I was, in this instance, able to code a solution. It's a solution which is very specific to my problem (i.e., T is Nullable(of SomeEnumeration)), but it's a solution nonetheless.
.net - Sort Generic List Based Upon A Different List?
Oct 29, 2010What would be the fastest way to sort a list that contains a list of objects, based upon another list? An example follows:Say I have multiple lists of employees. Each individual list has a common property value, say "Department". So I have a list of employees, in one list they all have the department string value of "Sales". In another list all the objects have a department value of "Finance". These lists of employees are then contained in a list which holds them all.
I have a second list, which should drives the sort order of the employee lists. The second list simply contains a list of strings like, "Finance", "Sales", "IT" and so on. I'd like my lists of customers to be sorted in the order of "Finance", "Sales", etc.I'm using VB.NET in .NET 2.0
Cast Inherited To Base Class?
May 19, 2010The program below trhows an error in the line "mTable2 = mTable.Copy". The error is: "Unable to cast object of type 'System.Data.DataTable' to type InherintanceQuestion.InheritedTable". This is because mTables is an instance of the InheritedTable class which inherits a DataTable and mTable is a DataTable. So, is there any way I can create the mTable2 to the mTable.copy to the mTable.
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[code].....
Generic TypeOf Operator - See If List Is A List(Of T) Variable - Error: "Type Expected"?
Jan 5, 2011Dim x = GetType(List(Of )) 'valid statement
Dim list As New List(Of String)
Now I want to see if list is a List(Of T) variable: Dim isList = TypeOf list Is List(Of ) On the last line I get a compile error: "Type Expected". Is there any cheap-performance TypeOf operator alternative for generics?
How To Cast Interface To Object (DailySchedule Class)
Jul 1, 2010I have a base class called Schedule and three classes inherited: DailySchedule, WeeklySchedule, MontlySchedule. Now I would like to build a form in which users can modify the schedule and I have to compile different parts of it depending on whether the schedule is daily, weekly or monthly. Then I want to have back the schedule modified. Which object can I use on the form?
I thought to implement on the base class an interface iSchedule and to pass the interface to the form, but when I'm on the form constructor how can I cast the interface to the correct class? e.g. in the form constructor I will have a sched variable as iSchedule, I can see that, for example, is a DailySchedule from an interface property called Type. But how can I cast the interface to an instance of the DailySchedule class and to access to its members?
Error - Red "List" Says Too Few Type Arguments To System.Collections.Generic.List(Of T)'
Mar 12, 2009I have converted c# .cs to vb:= I have 6 errors on:
Red "List" says Too few type arguments to system.Collections.Generic.List(Of T)'
Orange "Calendar" says Value of type 'System.Windows.Forms.Control.ControlCollection' cannot be converted to 'Form1.Kobush.Windows.Forms.Appointment'.
[code]....
Listview - Unable To Cast Custom Listviewitem Class In .net?
Apr 29, 2011I'm trying to use a custom listviewitem class that attaches additional information to a lisview item. Here is the class:
Public Class albumListViewItem
Inherits ListViewItem
Public hash As String
[code]....
When I try to cast a listviewitem to my custom class like this:
Dim albumItem As albumListViewItem = CType(lsvHidden.items.item(0), albumListViewItem)
I get the following error, "Unable to cast object of type 'System.Windows.Forms.ListViewItem' to type 'AudioMatic.albumListViewItem'."
.net - Filter Custom Dictionary With LINQ ToDictionary - "Unable To Cast Object Of Type 'System.Collections.Generic.Dictionary`2"
Jul 7, 2010I have created a Dictionary class (MyDictionary for the example). I am currently trying to pass MyDictionary into a function, filter it into a new instance of MyDictionary and pass this new instance into another method. When I am attempting to create the second instance from the filtered first instance of MyDictionary via Lambda Expressions and the ToDictionary Method, I am getting the following error:
Unable to cast object of type 'System.Collections.Generic.Dictionary`2[System.Int32,System.String]' to type 'MyDictionary'. I have simplified the example and recreated it in LINQPad and am getting the same error.
Here's the simplified version of my code:
[Code]...
Unable To Cast Object Of Type 'ImagesFlag' To Type 'System.Collections.Generic.IEnumerable`1[ImagesFlag]'
Jan 7, 2012And here is the code that produces the error
CODE:
How can i cast this one?
Have A Dynamic URL In Generic Class?
Apr 22, 2009I need to have a dynamic URL preferably from a Test Classformatting this design pattern to handle dynamic links from tests. instead of a constant HomePageURL.
Namespace TestDesign
Public Class HomePage
Inherits IE
[code].....