When I got a fieldsinfo-array of a class I know all of it's fields. Now, how can I access all of the fields of an instance of the same class by using the fieldsinfo-array? [code]I'm sure there exists a possiblity to get the value of the instance, but how?
View 5 RepliesI searched on the forum / Internet for the solution how a PropetryInfo object (of a Public property) can reveal if it has a Private Protected Setter ... it was all in vain .... all help I found was about how to "Set" value of a public property having a Private Setter.I would like to know if I have a PropertyInfo object of a public property, how would I know if its Setter is Non Public?
I tried, in a exception handling block, where I did a GetValue of the PropertyInfo object and then called SetValue by setting the same value back... but to my surprise it worked well and didn error out.
[Code]...
I'm checking If a border's child property is not set to nothing or equal to a given element, but whenever I run the program, it says that it's set to nothing and crashes. Here's my code:
If Not Me.Child.Equals(Nothing) Then ...
If Me.Child.Equals(value) Then ...
Both gives an error. What should I do to pass these lines? Also in C# it would look like this:
if(this.Child != null) ...
if (this.Child != value) ...
But this time it doesn't give an error.
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
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
[Code]...
Is it possible to call a protected method via reflection. I am using this:
Me.GetType.InvokeMember(Stages(CurrentStage),
Reflection.BindingFlags.InvokeMethod,
Nothing,
Me,
Nothing)
Which always calls a method with no params or return. The idea is that the user of my object (transactional processing of business logic) inherits the base class adds in a load of private methods to fire. They then add these method names to a list in the order they would like them fired and the code above will take care of firing them.
It works fine with public methods but not with private or protected methods in the same class (Protected because I have some 'standard' pre built methods to add to the base class). Realistically I could make the methods public and be done with it but my inner nerd wont allow me to do so...
I am assuming this is a security feature. Is there a way to get around this or does anyone have any suggestions on how to proceed but keep my tasty, tasty visibility modifiers in tact?
(NOTE: ITS IN VB.NET but a C# Answer is fine if that is what you are comfortable with).
How to get property.value from reflection.assembly?
Dim assembly As Assembly = assembly.GetExecutingAssembly()
For Each assemblyType As Type In assembly.GetTypes()
If assemblyType.IsSubclassOf(GetType(Form)) Then
[Code].....
I am trying to get the value of local path by doing the following[code]...
View 1 RepliesI 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.
View 5 RepliesI am retrieving several properties of a control. Here is how I used to retrieve properties (with pinfo of type PropertyInfo):
value = pinfo.GetValue(obj, nothing)
That worked well, but now I am facing a property that has a optional value, and I get an error message telling me that the number of parameters is incorrect. So I changed my code by this one:
Dim index As Object() = {Nothing}
value = pinfo.GetValue(obj, index)
At this point, I didn't get any error message, but this code doesn't retrieve the good value. It only works if I replace Nothing by the default value provided by the property accessor...
But I don't know in advance what this default value is! And this code is within a function that retrieves properties that doesn't have optional values, so I cannot change the code especially for one case or another..
I am working on .NET 2.0
EDIT: More precisions about the case leading to the problem
Here is an example of property leading to the problem:
ReadOnly Property Foo(Optional ByVal Number As Integer = -1) As String
Get
If Number = -1 Then
[Code]....
With this kind of property, none of the codes above retrieve the good string.
My best guess would be to try the first code for general purposes, catch the appropriate exception, and then dynamically retrieve the default value of the parameter (Number in that case) and its type, so that I can call getValue with this default value.
So, How can I retrieve the default value of the optional parameter?
How to get the object description using reflection. I can get the name, value, etc... but not the decription like in .net.For example the description for .Text is "Gets or sets the text associated with this control." I thought maybe using MethodInfo, but does not give the description.
Dim MethodObj As MethodInfo
Console.WriteLine("Methods:")
For Each MethodObj In GetType(TextBox).GetMethods()
Debug.Print(MethodObj.Name & " " & MethodObj.ReturnType.ToString())
Next
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)
[code]....
This function loops all properties of an object to create the updatequery to save te object to the DB.
We had to make some changes to it because of the introduction of nullable properties. If the property is nullable we would like to check the 'HasValue' property. This does works when it has a value. When the property has no value we get an 'Non-static method requires a target'-error at the CBool-line
An other way to check the 'HasValue'-prop of a property using reflection?
Private Function GetUpdateQuery(ByVal obj As Object, ByRef params As List(Of SqlParameter), Optional ByVal excl As String() = Nothing) As String
Dim sql As String = String.Empty
[Code].....
I am using the IndexOf function of the string class to find a specific instance of a string. And based on that I have a logic to do something. Below is the example of what I am doing. The code is in production and is working fine. But for some instance I am getting an "Object reference not set error". Yeah its intermittent.The requestXML is a string of xml data passed in as a paramter to a subroutine. I am fetching the xml string as a form post in a request object. The only thing I could think of getting this kind of error is when the requestXML string varia
requestXml = Request("requestXML")
SubmitRequest(requestXml)
Private
Sub SubmitRequest(ByVal requestXml
[code]....
Dim dir_info As New DirectoryInfo(strDirectory)
dInfo = New DirectoryInfo(strDirectory)
Dim fs_infos() As FileInfo = dir_info.GetFiles("*")
[Code].....
I am trying to create a new ProductID and stored it in a variable intProdID and also to display it on the Label.
But I encounter this error message to my surprise: Object reference not set to an instance of an object
this part of coding generate the error message:Do While DR.Read[code]...
I recently copied a code from internet, which gives me an error of Object Reference Not Set To Instance Of Object, NULL POINTER EXCEPTION. I couldn't understand where the problem lies.[code...]
View 2 RepliesThis was just thrown on me. It operates fine on first load but if I clear the box and click on the button that fires this code I get the NullReferenceException error. Everything is Null or "" on load so basically I am just resetting it
If (Not Trim(txtAssessmentSelectedType.SelectedValue.ToString) Is DBNull.Value And Not Trim(txtAssessmentSelectedType.SelectedValue.ToString) = "") And ((Not Trim(txtAssessmentSelectedTypeLow.Text.ToString) Is DBNull.Value And Not Trim(txtAssessmentSelectedTypeLow.Text.ToString) = "") Or (Not Trim(txtAssessmentSelectedTypeHi.Text.ToString) Is DBNull.Value And Not Trim(txtAssessmentSelectedTypeHi.Text.ToString) = "")) Then
DoAssessment = True
Exit Function
End If
The following code gives me an error: Object reference not set to instance of an object[code]...
View 10 RepliesI am currently trying to reference a new form that has been created, but I am unsure how I reference a particular instance of the form.
The form that has been created can have up to 4 different instances. Each one is created from the menu. The code that is executed is identical, with a parameter passed 1,2,3,or 4 The form is created with
Dim newScreenDisplay As New ScreenDisplay
and has all the usual text boxes and buttons etc. on it.The display is then kept up to date by refreshing it from variables. This task is performed by a background thread.What I can't work out is how to reference the specific instance of the form that I created as they all have the same name (newScreenDisplay).
I'm showing a form like this[code]...
Then I am trying to update a progressbar on that form from a public sub in a module, but I don't know how to reference it. I can't use "Me" because I'm not doing the updating in the forms code
I have a sub that initiates an instance of a library.object. That instance makes a connection to an instrument. Now I need to close it or change properties/run method from another sub. How do I reference this instance?
Public Class Form1
Private obj As AxCBMCOMMLib.AxCBMComm
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
[code]....
This is on my page load. I always encounter Object reference not set to an instance of an object on my ddlStatus drop down list.
HTML
Dim lnkUpdate As LinkButton = FormView1.FindControl("UpdateButton")
Dim ddlStatus As DropDownList = FormView1.FindControl("DropDownList4")
Dim lnkEdit As New LinkButton
Dim lnkDelete As New LinkButton
Dim CurrRow As GridViewRow
[Code] .....
I have Form1 calling Form2 and Form2 calling a sub from anther class on load that populates a combobox.The sub is throwing the exception "Reference not set to an instance of an Object". I do something nearly identical on the main form and it works perfectly.[code]
View 3 RepliesI am trying to get the bound values from a row in a ListItem. I have a button on each row that when clicked will perform a task (sending an email message to the person who's name and email address is in that listitem row. So, I have an event handler tied to the listview, and I am trying to get to the underlying datarowview to extract the data items.Here's what I have in the event handler:
Protected Sub lvUsers_ItemCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ListViewCommandEventArgs) Handles lvUsers.ItemCommand
Dim diCurrentUser As ListViewDataItem = CType(e.Item, ListViewDataItem)[code]...
Now, it fails at the line where I am trying to access the contact_email element in the DataRowView object.What an I doing wrong?
I've written a new DAL and BLL, but when I try to create an instance of my class, I get an Object Reference error, is there anything particular I should be looking for? I am fairly new to this concept?
Call is such:Protected Sub btnSignin_Click(ByVal sender As Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles btnSignin.Click Dim l As New Log()l.Log = "Attempted staff login with username [" & txtUsername.Text & "] and password [" & txtPassword.Text & "]"
[Code]...
Intellisense highlights no problems and if I Build the web site in VS I get a few warnings about schema information in the web.config (unrelated), otherwise no problem.
Is it possible using Reflection or some other method to obtain a reference to a specific class instance from the name of that class instance? For example the framework for the applications I develop heavily uses public class instances such as:
Public bMyreference as MyReference = new MyReference
Then throughout the application bMyReference is used by custom controls and code. One of the properties of the custom controls is the "FieldName" which references a Property in these class instances (bMyReference.MyField) as a string. What I would like to be able to do is analyze this string "bMyReference.MyField" and then refer back to the actual Instance/Property.
In VB6 I would use an EVAL or something simular to convert the string to an actual object but this obviously doesn't work in VB.net. What I'm picturing is something like this:
Dim FieldName as String = MyControl.FieldName ' sets FielName to bMyReference.MyField
Dim FieldObject() as String = FieldName.Split(".") ' Split into the Object / Property
Dim myInstance as Object = ......... ' Obtain a reference to the Instance and set as myInstance
Dim myProperty = myInstance.GetType().GetProperty(FieldObject(1))
The code is shown below:-
Function fnt_db_JDE(ByVal connName As String, ByVal strSQL As String) As DataTable
Dim result As New DataTable
Dim dsSysConfig As New DataSet
Dim xmlPath As String = ini("Root") & "SysConfig.xml"
[code]....
The error is with the connStr = '' line.
Whats the best way to instantiate a class so that i can have access to the object from diffreent forms and classes?
View 2 RepliesI was trying to access the following property using Reflection because I don't have the original source code (suppose this was decompiled through Reflector). It seems that something is special about it being "private virtual" or maybe because it has "_" in the beginning of the property. I can access all the other private properties no problem except this one. Just can't figure out what I am doing wrong:
private virtual String _MyProperty
{
get
[code]......