I've got a set of static "enumeration" classes that I'm using to hold meaningful variable names to represent meaningless code values I receive on an input file. Here's an example of one.
Public Class ReasonCodeValue
Private Sub New()
End Sub
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.NET I want to clone a value type's fields. How can i set a field value on a value type using reflection (or something else dynamically)?
This works for reference types but not for value types. I understand why but I don't know an alternative.
shared function clone(of t)(original as t) as t
dim cloned as t
'if class then execute parameterless constructor
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I have this code to get the default constructor:
Public Function f(ByVal t As System.Type) As Object
Return t.GetConstructor(New System.Type() {}).Invoke(New Object() {})
End Function
I need to pass values to the Constructor as
Public Function f(ByVal t As System.Type) As Object
Return t.GetConstructor(New System.Type() {someInteger,someString,etc.etc}).Invoke(New Object() {})
End Function
Also I have 3 classes of Type T, with all having different parametric constructor. It's important for me to have it generic as the Classes of type T might increase in future with less or more parameters.
I'm trying to obtain the values using the prospective GetValue(s) methods but I don't understand the syntax of the documentation. I'm sending the correct bindings (I believe) to filter the fields, and properties that i'm interested in usually
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E.g. how do I get VB.Net to statically type a local variable to be the static type of the expression on the right had side of the assignment?
View 1 RepliesI have a field which is static and readonly. The requirement is that the value should be allocated to the field at the login time and after that it should be readonly. How can i achieve this ?
public static class Constant
{
public static readonly string name;
}
How do I set a field value in a VB.NET module using Reflection?
View 2 RepliesConsider a process, in which multiple Application domains are created. Can we share a single static field across these Application domains or can we pass this static field across these application domains? How does CLR handle this?
View 1 RepliesThis is probably a simple one but I can't seem to figure it out. I have a bunch of form items created by the form designer declared as (in frmAquRun.Designer.vb)
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I cannot get the following to work for me: its the section that sets the default for system.data.linq.binary. The database I work with doesn't allow nulls in any field. So I generally run my buffer through this routine to populate defaults and then set the real values independently, (this works when I miss a field). I can set the Linq table field = fakeBinary and it works like a charm. Thus, I don't understand why using reflection can't pull of the same thing.
Ex: Me.CM20500WindowBuffer.Reconcile_Messages = New Byte() {0} works.
Try
Dim fakeBinary As System.Byte() = {0}
For Each fld In nObj.GetType().GetProperties
Select Case fld.PropertyType
Case GetType(Byte)
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I have an open source project I converted to vb.net. I solved all the errors, except for one. This is the C# line
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I am trying to edit a dbf table. I would like to be able to rename field headings and change the field type, ie string or dbl, and the size of the field. is this possible to do with vb.net. I have connected to the dbf file but after that am lost on what to do.
View 3 RepliesWhat I wanted to do was, given the table name (as string), use reflection to instantiate the get method for specific fields (defined as properties with Get and Set methods.
Public Property VC60() As String
Get
Return _VC60
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I am trying to write a function that has an object parameter. That object will always be an BindingList. That BindingList will be of some unknown (at design Time) class. I think I've figured out how to get the type of the collection object, but now here the tricky part. I'm trying to create a function that can handle any type of collection and be able to return an item from that collection. I need to create a new object of that type and return it from the function. [Code]
View 1 RepliesI am trying to create an Excel file using reflection. The reason, the application will be running on many machines some of which may or not have excel installed. I decided to embed the "Microsoft.Office.Interop.Excel.dll" and via reflection generated the excel spreadsheet. The code I am trying to resemble is:
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Is there a way for a property to access its own name and type at runtime using reflection? I want to access this info without hard coding the name or index of the property in the class.
Simple Example Code:
Private ReadOnly Property MyProperyName() As String
Get
Console.WriteLine((Get Current Property Info).Type.ToString)
Console.WriteLine((Get Current Property Info).Name)
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I'm trying to create an object Of a specific type. I've got the following code, but it fails because it can't cast the new table object to the one that is already defined. I need table to start of an IEnumerable type so I can't declare is an object.
Public sub getTable(ByVal t as Type)
Dim table As Table(Of Object)
Dim tableType As Type = GetType(Table(Of )).MakeGenericType(t)
[code]....
is there a way of changing a variable type at runtime?
I'm attempting to dynamically register entities and configurations with a context (ef4 code-only). I would normally do:
Private Shared Sub ConfigureDatabase(ByRef Builder As ContextBuilder(Of ContextExtension))
'Load configurations for each of the tables (Entity sets) in our database...
ConfigureEntity(Builder, New ContactConfig)
End Sub
Private Shared Sub ConfigureEntity(Of T)(ByRef Builder As ContextBuilder(Of ContextExtension), ByVal config As EntityConfiguration(Of T), ByVal setName As String)
'Register the entity configuration with the builder
Builder.Configurations.Add(config)
'Register the entity set name with the builder
Builder.RegisterSet(Of T)(setName)
End Sub
Where ContactConfig is a class which inherits EntityConfiguration(Of Contact) and Contact is a class which implements an interface IEntity (IEntity is common to all entities). So... I need to search a namespace (say Project.DB.Client) for all signatures that match:
EntityConfiguration(Of <Class which implements IEntity>)
How can I achieve this?
I coded a class that scans an object and maps data from a data table into each one of the corresponding properties, it works very well, however I am not able to set the property of one of the child (coplex objects)
Public Class CntrConfHdr
Private m_CntrConfHdrID As Double
Private m_HeaderCode As String
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I want to set the value for the child object TypeCurrency.TypeCurrencyID thus I set the value of the variable sTargetPropertyName to TypeCurrency.TypeCurrencyID but the application willnot work stating that the property can not be found.
Traditionally, class/type name is literally spelled inside its definition.
Public Class MyCustomClass
Public child As MyCustomClass
Public Shared Function Clone(ByVal original As MyCustomClass) As MyCustomClass
End Class
This is not a problem most of the time; C-languages even use class name as constructor methods' name. But consider a generic declaration:
Public Class MyListOfIntegers
Inherits MyCustomList(Of Integer)
End Class
[code]....
This scenario has 2 issues. The first one is that constructors are not inherited, and you have to provide pass-through wrappers in every derived class, — this is quiet dumb, but tolerable. The second issue is more severe: derived class inherits CloneMe() method which returns MyCustomList(Of Integer) , not MyListOfIntegers ! Every returned value must be manually DirectCast 'ed for further use with methods that expect MyListOfIntegers . This issue, together with the first one, renders inheritance of generic class almost useless.
So I need a "MyClass" alternative for static type-binding inside type definition. In case of generic type that is referencing other compound types, task could be accomplished by adding second parameter to type section:
Public Class MyCustomList(Of T, TList)
...
Public Function CloneMe() As TList
[code]....
But since we must reference our own type, it would create an infinite recursive loop of additional typeparamlist arguments. How can this be resolved, aside of creating separate classes without generics?
I'm trying to check if a variable has been defined as a nullable Guid. eg.
Dim myGuid As Nullable(Of Guid) or Dim myGuid As Guid?
It seems doing a myGuid.GetType returns the underlying type, that is type Guid, not Guid?. So testing myGuid.GetType Is GetType(Guid?) always returns False.How do I find out if myGuid is a nullable type?
Ed: I can do the following, which correctly returns True for "Guid?" and False for "Guid":
Not Nullable.GetUnderlyingType(GetType(Guid?)) Is Nothing
The problem is that I don't know how to retrieve the nullable type from the variable itself, in order to test it. I've only been able to get the underlying (non-nullable) system type.
I've written a db helper function. I pass it an object comprised of public members, representing the row data of a table. The members are the table columns.Using reflection, I loop through these public members to create an INSERT statement for a command object and populate its parameters with the values in those members. So far so good.But now there's a table which has a uniqueidentifier column which I must not populate from the row object, as it defaults to "NEWID()" (using SQL Server 2008). Instead of skipping all Guid columns, which would be easy, I only want to skip ones defined in the row data class as "Guid" (non-nullable).Basically, I'm using the Guid? (Nullable) type to indicate it's ok to populate that uniqueidentifier column with data. If it's non-nullable, that tells me to skip it because the column has a NEWID() default value.
I'm passing a type name and some parameters from C# code into a navigation framework written in VB. The navigation framework looks for a constructor on the type that matches the parameters passed in using Type.GetConstructor(Types()). The constructor that I'm looking for expects an array of integers Integer() in vb. But it gets an array of System.Int32. I've gone so far as to try this:
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And the VB code still sees System.Int32 on the other end, which means that it doesn't find the constructor.
I am pulling data from a local MSSQL database using a stored procedure, then send the data to a web service. Every part of the component works well except for a pesky problem will a DBNull being returned from the DataRow field, when I know that the field is not null and has valid data. The database and associated INSERT statements that add to this field are designed to not allow NULL entries. When I debug break the program on or right before the line that throws the error I see that the field has valid data for the current row.If I add a null check to the code (as below) the operation continues as normal:
Dim dataResultsTable = Me.myViewTableAdapter.GetData(int)
For Each myDataRow In dataResultsTable.Rows
If worker.CancellationPending Then
[code]....
Why is the read operation returning DBNull instead of the data in the database?
EDIT: Just to be clear, the operation does return the proper data, but the data is not being saved into the variable.
I am working on a project where my class has to execute VB code provided by the user, to make it simple I am trying to recreate my own eval function, I am using the following code I found on the web to do this task.
Imports Microsoft.VisualBasic
Imports System
Imports System.Text
Imports System.CodeDom.Compiler
Imports System.Reflection
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The problem with code is that it can't access any variables or there values, so I have decided to get the variable names, there values types and there types dynamically and recreate them in the class that is being created dynamically. Any way to get the variable names there types and values in the current class or method, so that I can recreate them, and execute the user passed code, the user knows what variables are in the current class or method and there datatypes but he don't know there values as they may have changed, so he can't initialize them. Is there a way to do this, this code will be called in an asp.net page on page_load event, the code passed by the user is stored in the variable vbCode that is passed as a parameter.
I have a parent class that is also a factory. For example:
Public Class Factory
Public Function clone() as Factory
' Some logic here
[code].....
I am working on a card game, and i get this werid error:
A first chance exception of type 'System.Reflection.TargetParameterCountException' occurred in System.Windows.Forms.dll
The code that is cousing this error is:
Private Delegate Sub ShowcardDelegate(ByVal test As String, ByVal objtest As Object, ByVal value As Boolean)
Private Sub Showcard(ByVal test As String, ByVal objtest As Object, ByVal value As Boolean)
If objtest.InvokeRequired Then
[code].....
I have had several occasions recently to access a specific class several times over a relatively small time frame.So I've been storing the value of the class in Session and trying to access it on page load, if it's not available creating a new instance and storing that in session.
So instead of constantly replicating the same code for different classes on different pages I'm trying to create an extension method to do this for me.
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I'm stuck on what to do when I make my new instance of my class (it would have to have a New() sub)
I'm not sure where to go from here... or even if this is the best way to do it.
I am trying to get the Sum values of a Column and want to check if entered value in Textbox is valid. Here is my code below
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I've got a SQL Database with the field type Date, when i load any data such as 06/04/2010 into my masked textbox it shows as 64/20/10 (without the leading zero's so the date shows wrong.
Also how can I set it to be dd/mm/yyyy and not mm/dd/yyyy?
I am inserting the nChar type value into sql db using the vb.net. Its simple insert query but i dont know why not inserting into db.
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