Reflection - How To Get Variable Names Types / Values In Current Class
Feb 1, 2011
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
[Code] .....
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.
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Dec 18, 2009
What i'm trying to do:
I've got a library which includes a class:
Class Human
End Class
and another class which refers to the human class
Class ASD
Private somevar as new Human
End Class
Ok now i've got a problem, i wish to rename my class Human, to Man. i've got to change Human to Man 2 times, which is OK but the problem is that in the real case, its not just 2 times, its like 500 times or more.
Well its something like a PHP on Javascript.
the following shows the solution of what i'm trying to do, but its in another language PHP/Javascript:
note: in php $ sign declares a variable, echo writes the variable out
CODE:
Is there anyway to do that with VB?
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Jan 9, 2009
Trying to understand the best way to do this and I'm can't get it figured. Here's basically what I have:
Public Class CardParsingClass
Private iAcctIDStart as integer
Private iAcctIDLength as integer
[code]....
I've only included 2 of the class level fields here but there are actually 30, so that's why I was hoping to be able to send the name of the field to set and the value to set it at in the SetValue function. So in some other routine in the program I'd like to be able to issue the following call:
SetValue("iAcctIDStart", "3")
But then when I get into the SetValue routine, I'm not sure how to proceed. I thought about a case statement that would basically be this:
select Case strFieldToSet
case "iAcctIDStart"
iAcctIDStart = cint(strValue)
[code]....
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Nov 17, 2009
I'm quite new to Visual Basic - using Visual Studio 2008 and can't seem to find a way to do the following:
I have a few tables in a SQL Server database and have used LINQ to SQL to create classes of those tables.
Here's a cut down example of what I'd like:listbox1 filled with table names - APS, SMPS, WCPC, CFLAPS
Then from the SelectedIndexChanged event, listbox2 should populate column headers of the selected table.
I have no issues getting data from the database, and can access all of these headers through the anonymous type objects created from a LINQ query (eg APS.ID, APS.count etc), but populating a listbox with these variable names rather than the data inside them seems rather elusive.
This is probably a cross platform coding question rather than VB specific, so if you have a solution in C# or whatever I'd be happy if you could let me know.
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Jun 21, 2010
I have valued pairs, attributes names and values in one hand, and I have an object with attributes. I need to set the values of those attributes. I need something like [code]
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Oct 25, 2011
We are seeing an Exception while trying to get the types from an assembly using Reflection.
Dim assemblyLibrary As Assembly = Assembly.Load(System.IO.File.ReadAllBytes(testSetAssemblyPath))
'Getting all class types
Dim classTypes As System.Type() = assemblyLibrary.GetTypes()
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Mar 19, 2010
I would like to use reflection on an anonymous type resulting from a LINQ to SQL query. I know that reflection on anonymous types works in general. The following code successfully generates a propertyinfo array with two elements:
Dim MyObject = New With {.Col1 = 1, .Col2 = "Test"}
Dim t As Type = MyObject.GetType()
Dim pilist As PropertyInfo() = t.GetProperties
[Code].....
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May 31, 2011
I am trying to work with classes and variables and don't seem to understand some behavior that is going on.
first off the class
Public Class csSession
Public ID As Integer
Public Name As String
End Class
Usage and behavior (example code)
Dim S1 as new csSession
Dim S2 as new csSession
S1.ID = 1
S1.Name = "1st Session"
S2 = S1
S2.ID = 99
When I assign S2 = S1 all the values of S1 passes to S2 but also there is a "link" or bond between the two variables now. If I change the values of S2 this automatically changes the values of S1!! Why does this happen and how can I prevent it? I just want to pass the variables values contained S1 to S2.
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Sep 5, 2011
I am doing work for a client who has lost the source code for one of their VB.Net WinForms applications. The assembly they have is not obfuscated at all. I am trying to recover as much of the source as I can as C# source and have tried several tools for decompiling assemblies, including Reflector, ILSpy and JustDecompile (all the latest versions), but they all produce code with a huge number of errors in them. Because of the large number of errors in the generated code, I am going to ask about the specific errors (in different questions), get more directed answers and in this way try shed some light on why all the tools are having difficulty decompiling this assembly. This question pertains to the fact that the code generated by all these tools always have a large number of invalid member variables (fields) such as the following:
private short $STATIC$Report_Print$20211C1280B1$nHeight;
private ArrayList $STATIC$Report_Print$20211C1280B1$oColumnLefts;
private StaticLocalInitFlag $STATIC$Report_Print$20211C1280B1$oColumnLefts$Init;
why the generated code has these invalid member variables?
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Aug 15, 2011
I have a DataGridView which populates from an SQL query just fine in default mode
using these table names
[firstName] [varchar](20) NOT NULL,
[lastName] [varchar](20) NOT NULL,
[code]....
I have edited the column headers and set the column names to the same values as my table names yet the data is not showing in form load I have set datagridview.AutoGenerateColumns = False I know the data is there if I delete datagridview.AutoGenerateColumns = False then the data is shown with the default headings?
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Jan 8, 2010
The scenario is I would like to be able reference two similar 3rd party assemblies (e.g. assem1 and assem2) which both define a type with the same fully qualified name (e.g. Example.MyType). Is there any way to distinguish between these and refernce them seperately? I believe the answer is no but confirmation or correction would be handy. Edit: Answered for C# 2.0 and higher below but need an answer in VB.Net 1.1
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Nov 2, 2009
I am using a structure array with multiple member names with 2 types. My question is can you single out one of the member names and add its total? kinda like this...
HTML Code:
structure structureName
dim a as string
dim b as double
dim c as double
[code].....
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May 31, 2012
Now I have the need to get a current value from a bindingsource in a property of a user control.In a previous thread I had tracked down the "Object variable or With block variable not set" to the return in the Get block of a property. At the time I was only using the Set so I just commented out the offending code until I needed it.
[Code]...
The error does not occur during a system compile, only upon saving the container object of the user control. As I said the Set works correctly, only the Get causes the error.I would like to know what I am missing/misunderstanding and am open to other suggestions of handling retrieving the current value of a bindingsource in a user control.
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Feb 6, 2011
I am writing a code-generator that will need to output some miniscule portions of VB.NET code, and since this is a code generator that will add user-provider code, I'd like to try to avoid type name conflicts with types or names in the user-provided code.
In C#, I can prefix types with global:: to make sure they're matched from the global type namespace hierarchy, rather than some local name, but is there a similar system for VB.NET? ie. this: global::System.String
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Jan 16, 2012
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.
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Sep 6, 2010
I'm trying to use reflection to get the instance of a class in vb.net. I have a class 'A' in my web project and to test it, i create a new aspx page and try to write the following:
Dim t as Type = Type.GetType("A")
This returns "Nothing". But if i do this:
Dim inst as A = new A()
Dim t as Type = inst.GetType()
t's type is "A"
So how come i can't get the type with GetType even if the name is exactly the same? It does works for things like System.Math though
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Feb 19, 2009
I'm trying to use reflection to populate the properties of an array of a child property... not sure that's clear, so it's probably best explained in code:
Parent Class:
Public Class parent
Private _child As childObject()
Public Property child As childObject()
Get
Return _child
[Code] .....
The issue is now trying to get that array assigned to the parent object (using reflection). It shouldn't be difficult, but I think the problem comes because I don't necessarily know the parent/child types. I'm using reflection to determine which parent/child is being passed in. The parent always has only one property, which is an array of the child object. When I try assigning the child array to the parent object, I get a invalid cast exception saying it can't convert Object[] to.
Basically, what I have now is:
Dim PropChildInfo As PropertyInfo() = ResponseObject.GetType().GetProperties()
For Each PropItem As PropertyInfo In PropChildInfo
PropItem.SetValue(ResponseObject, ResponseChildren, Nothing)
Next
ResponseObject is an instance of the parent Class, and ResponseChildren is an array of the childObject Class.
This fails with:
Object of type 'System.Object[]' cannot be converted to type 'childObject[]'.
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Jun 2, 2009
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
[code].....
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Jun 18, 2012
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.
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Feb 23, 2009
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
[Code]...
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.
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Apr 14, 2010
I know its unlikely but I was wondering if there is any way to get the comments (i.e. the bits after the ''') of a class or property..? I have managed to get a list of properties of a class using the PropertyInfo class but I cant find a way to get the comments / description.. I need it for a guide I am writing for the administrators of my site - it would be great if it could automatically update if new properties are added, so there is no need to worry about updating it in the future too much.
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Apr 28, 2009
how to create an instance of a class then add properties to the class, set those properties, then read them later. I don't have any code as i don't even know how to start going about this. C# or VB is fine.
My system has a dynamic form creator. one of my associates requires that the form data be accessible via web service. My idea was to create a class (based on the dynamic form) add properties to the class (based on the forms fields) set those properties (based on the values input for those fields) then return the class in the web service.
additionally, the web service will be able to set the properties in the class and eventually commit those changes to the db.
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Mar 11, 2011
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Dim resources As
System.ComponentModel.ComponentResourceManager = New System.ComponentModel.ComponentResourceManager(GetType(_Class))
[code]....
How can I reach that sqlparameter collection via fieldinfo or other related classes in >NET Reflection?
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Dec 30, 2011
What 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
[code].....
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Jan 15, 2009
Code snippet:
Dim target As Object
' target gets properly set to something of the desired type
Dim field As FieldInfo = target.GetType.GetField("fieldName", _
BindingFlags.Instance Or BindingFlags.Public Or BindingFlags.NonPublic)
field.SetValue(target,newValue)
This snippet works perfectly IF target is set to an instance of a CLASS.However, if target is set to an instance of a STRUCTURE, the code does not actually change the value of the field. No error, but the value remains unchanged.And, oddly, if I'm stepping through code, watch the SetValue fail to do anything, and immediately go to the Immediate window and type exactly the same SetValue operation, that works.
Edit:
Per request from Jon Skeet, actual code:
Private Shared Function XmlDeserializeObject(ByVal objectType As Type, _
ByVal deserializedID As String) As Object[code].....
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Jan 11, 2012
Users can easily rename special folders like Computer, Network etc. to whatever they like. Also if the computer is using a different locale, the name of those folders will also be different.I want to get the current names of all special folders like Computer, Recycle Bin, Network etc. in my app. Is there a way to do this? A specific API? A registry value?For eg, user renames My Computer to Super Computer. My app should show that My Computer's name is Super Computer.
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Sep 13, 2010
I want to retrieve private (implementation and other) methods of a class which implements an interface and also is derived from (inherits) a base class.How can I achieve this using reflection?This is wat m tryin to do. I need to view these private methods and their contents, I don't want to invoke them.
Dim assembly As System.Reflection.Assembly
Dim assemblyName As String assemblyName = System.IO.Path.GetFullPath("xyz.dll")
assembly = System.Reflection.Assembly.LoadFile(assemblyName)
assembly.GetType("myClass").Getmethods(Bindings.NonPublic)
assembly.GetType("myClass").GetMethods(BindingFlags.NonPublic) isn't working
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Oct 15, 2010
I'm making a little program in where i'm trying to invoke a method from a class dynamically with so called Reflection.The class I'm trying to call is called ContactList and i try to invoke the method in this class called count. The assembly itself is called Contact.ExeNow I have the following code:
Public Function InvokeContacts() As Integer
Dim ContactsAssembly As Assembly = Assembly.LoadFrom("Contacts.exe")
Dim Mycontactlist As Type = ContactsAssembly.GetType("ContactList")
[code]....
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May 18, 2008
I am currently using reflection to retrieve all properties of a class. I return a collection of PropertyInfo objects and all is working fine.
My problem is, I want to check if a property has been defined in a base class implementation and is therefore inherited in the current class.
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Jun 1, 2012
I know that the MenuItem class contains an internal class named MenuItemData, which contains itself an internal member named onDrawItem. Given a MenuItem, I want to retrieve the object corresponding to the member onDrawItem. But all I manage to do is to get the FieldInfo, not the object itself.
Here is my code:
Dim obj As Object
Dim fi As FieldInfo
Dim item as System.Windows.Forms.MenuItem
Dim mType As System.Type
[Code] .....
When reaching the last line, I get an error saying something like that (it's traduced):
The field 'onDrawItem' défined in type 'System.Windows.Forms.MenuItem+MenuItemData' is not a field of the target object of type 'System.Windows.Forms.MenuItem. I don't know what object to pass to the GetValue function on the last line. My goal is to remove the base eventHandler of the menuItem, named DrawItem. See this post and the function RemoveClickEventin the accepted answer for a better understanding.
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