System.String is a class type, but why we can use it without instantiate it with New keyword?
For example:
Dim CommandLineParameters As String = Microsoft.VisualBasic.Interaction.Command
No new keyword being used at all?
I have an Account Class that is able to create notes(Class), however i am able to create the note object by itself which is not the desired outcome, i want only the account class to be able to create the note object. Another Example would be, an order item should not be created without an order class. But how do you enforce this in vb.net.
View 8 RepliesI have a WPF windows project with a base Window, and then a series of user controls which I want to add at runtime based on a string from a file. I'm reading a string say "controlA" and i want to create an instance of the user control with the class name "controlA" and then add it to a base window. I want to have a constructor, but for now I would just like to see it work without.I need to do this: read a string (which is the user control type), create an instance of a user control based on that string, and then add the instance to the current WPF window. I've been playing around with Reflection.Assembly, getType, System.Activator.createInstance, Invokemember, CreateObject, and a few others. I can't seem to get it to work.
View 5 RepliesI am getting the following erro message: "Unable to cast object of type 'System.String' to type 'System.Predicate`1[System.String]'." on the line of code: If Not StrgFrag.Exists(wrd) Then I was expecting a True/False response and assumed it would work given that wrd is a String variables and StrgFrag in a List(of String). Do I need to reference the wrd variable differently? Dim StrgFrag As New List(Of String)
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Code: Dim dom As New DOMDocument30 dom.async = False
dom.Load(serverAddress & "/App/filelist.jsp?type=content")
For i = 0 To dom.childNodes.item(1).childNodes.length - 1 downloadfile(dom.childNodes.item(i), mcount, currentpath) Next
The above code is activated upon clicking of a button. i have the server address declared. and using the domdoc to load the jsp file to generate the xml data. and using for loop, i call the download file function which accepts the following parameters
Code:Public Sub downloadfile(ByVal domdoc As Xml.XmlNode, ByVal totalcount As Integer, ByVal currentpath As String)
The totalcount and currentpath work fine, but when i pass in the dom.childNodes.item(i) , error pops up.
--------------------error message------------------------------------------Unable to cast COM object of type 'System.__ComObject' to class type 'System.Xml.XmlNode'. Instances of types that represent COM components cannot be cast to types that do not represent COM components; however they can be cast to interfaces as long as the underlying COM component supports QueryInterface calls for the IID of the interface.-------------------------------------------------------------------------------
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I am getting this error when I am tring to load string type to data table)
Using connection As New SqlConnection("connectionstring;")
connection.Open()
Using Command As New SqlCommand("SELECT ClientId,forename,surname from t_clientdetails
[code].....
I get the below error Unable to cast object of type 'System.String' to type 'System.Data.DataTable'.This is the code I'm using
Dim str As String = String.Empty
If (Session("Brief") IsNot Nothing) Then
Dim dt As DataTable = Session("Brief")
If (dt.Rows.Count > 0) Then
[code]....
Unable to cast object of type 'System.String' to type 'System.Windows.Forms.TextBox'.
View 12 RepliesI am getting a really bizarre error and it makes no sense at all.Basically I have a user entity which has a Password property. This property is of Type Binary, the server data type being Binary(512).I am reading this value in and converting it to a byte array. However whenever I run my code I am getting a completely unrelated error of Unable to cast object of type 'System.Guid' to type 'System.String'.This strikes me as very odd since I am not using a property or variable of type string or GUID anywhere in this procedure where it falls over.
The code is below:
Public Shared Function ValidateUser(ByVal username As String, ByVal password As String) As UserValidationMessage
Using db As New EntityMapDataContext
Dim u = From user In db.Users
Where user.Username = username
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When testing the followng code from Mastering VB2010, I get an Unable to cast object of type 'System.String' to type 'System.IFormatProvider' exception.In the Button1_Click event code Dim strmOut As New System.IO.StringWriter(SaveFileDialog1.FileName)the 'SaveFileDialog1. FileName' is underlined with a green squiggle and displays the following tool tip:Runtime errors might occur when converting 'String' to'System. Iformat Provider'.This is apparrently the problem but what does it mean and how do I fix it to get the code to work? 'Code being tested that runs the exception:Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click.[code]
View 12 RepliesI have a page that get value from SQL. I'm having a problem when I initialize Label object with field having TEXT data type.[code]...
View 4 RepliesI have a bit of trouble right here, I am trying to get the data from the site and input them in the listview. Well, when my main app start to load through on debug, then it start to display a warning. The warning is: Unable to cast object of type 'System.String' to type 'System.IFormatProvider'.
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I'm getting a sporadic 'Unable to cast object of type 'System.Int32' to type 'System.String' Exceptions at .SingleorDefault() in the below code. It works 9/10 times but randomly it throws an exception. I made sure that SettingID that i'm passing has no Null Values and the data in the table always exists for the settingID, and i'm always passing SettingID as Integer.
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iNCEEB = .First.NCEEB '<-- Im getting the error in this line, iNCEEB is integer .First.NCEEB is short.
NCEEB Server Datatype property is smallint
where is that "to type 'System.String'." coming from?
I'm using vs2008 and mssql2008.
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I has the following code in my vb.net:
Code: Dim sql2 As String = " SELECT * FROM Etiqa_Image_Details where TransmissionID='" & Request("id") & "' " With objDB.OpenDataReader(sql2) While .Read()
If .Item("ImageType") = "Invoice" Then imgInv.ImageUrl =
[code]....
However,i get this error while retrieving the image path(Varchar in sql server 2000) and display the image on the web.
Unable to cast object of type 'System.String' to type 'System.Byte[]'.
Actually in my database, i am just storing the image path where the image store...And now when I browsing the web, it should get the image path out and find the image through the image path and then display on the web....
[code]Unable to cast the type 'System.String' to type 'System.IComparable'. LINQ to Entities only supports casting Entity Data Model primitive types. I'm in a DDD-layered application, so the parameter should stay the same as the called method is an overridden interface (eg. if i change this, i have to do this for 200 times or so, because it's in VB.Net and not in C# (= 1 change) )
View 1 RepliesPrivate
Sub cmdExit_Click(ByVal
sender As System.Object,
ByVal e
[code]....
dim myCollection as new Specialized.StringCollection
dim myFoundThings as new ArrayList
dim index as Integer
dim newResultMemberName as String
[code]....
This is part of some code that will run without user interaction once it's spinning away, and I need to create a unique object from some items found in a StringCollection, naming the objects using information found in the strings stored in that StringCollection.
Unable to cast COM object of type 'System.__ComObject' to class type 'rjsDocMan.Folder'.Instances of types that represent COM components cannot be cast to types that do not represent COM components; however they can be cast to interfaces as long as the underlying COM component supports QueryInterface calls for the IID of the interface.The code where it is flagging the error is:
<div style="color: Black; background-color: White;">
treeview += AddChildren(Session("DocMan").RootFolder)
</div>
[code].....
Value of type 'System.Func(Of String, String)' cannot be converted to 'System.Converter(Of String, String)
Why? They are both effectively a function pointer (or delegate?) to a function that accept a string and return a string.
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.
[Code]...
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 was trying to inherit System.Type. this is what i have:
[Code]...
and anyway the real problem is that inheriting System.Type without declaring my derived class as 'MustInherit
I converted the Microsoft's datagridviewcustomcolumn sample into vb.net to host maskedtextbox control. The maskedtextbox column works fine when it is not bound to database field. But it raises exception when it is bound. I have shaded the line that raises the exception.
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I have a requirement where I need to have a "type safe" way of accessing property names, without actually instantiating an object to get to the property. To give an example, consider a method that takes as arguments a list of IMyObject and a string that represents a property name (a property that exists in IMyObject).
The methods implementation will take the list and access all the objects in the list using the property name passed... for some reason or another, we won't dwell on that!!
Now, I know that you can do this using an instantiated object, something like ...
Dim x as MyObject = nothing
Dim prop As PropertyInfo = PropHelper.GetProperty(Of MyObject)(Function() x.MyProperty)
Where my helper method uses reflection to get the name of the property as a string - there are numerous examples of this flying around on the web!
But I don't want to have to create this pointless object, I just want to do something like MyObject.MyProperty! Reflection allows you to iterate through a types properties and methods without declaring an object of that type... but I want to access a specific property and retrieve the string version of its name without iteration and without declaring an object of that type!
The main point here is that although I am trying to get the property name as a string... this is done at run time... at compile time, I want this to be type safe so if someone changes the property name, the compilation will break.
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.
I had write code (just for learning), the codes :
dim Temp as string
Temp = Recordset("
Table_Field")
but, when I start Debugging the error messages "Unable to cast object of type 'ADODB.InternalField' to type 'System.String"
I'm new to VB 2005, the code below is actualy coded from VB 6 and just converted it to VB 2005. I'm having trouble with line that's on bold letters.In VB 6 this works just ok. By the way the error message is "Unable to cast object of type 'System.String' to type 'ADODB.Connection'." [code]
View 5 RepliesI have these errors when creating my website?
Error 1Server Error in '/ Application. -------------------------------------------------------------------------------- Conversion from type 'DBNull' to type 'String' is not valid. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.InvalidCastException: Conversion from type 'DBNull' to type 'String' is not valid. Source Error: Line 64:
Line 65:
I am getting this error No mapping exists from object type System.String[] to a known managed provider native type.The code is
Dim conn1 As SqlConnection
conn1 = New SqlConnection("Data Source=win2008-2;Initial Catalog=h1tm11;User ID=sa;Password=#1cub3123*;Persist Security Info=True;")
' Dim conn1 As String = ConfigurationManager _ .ConnectionStrings("Connectionstring").ConnectionString()
'conn1.ConnectionString = ConfigurationManager.ConnectionStrings("Data Source=win2008-2;Initial Catalog=h1tm11;User ID=sa;
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the error occurs at adapter.Fill(table)
Dim addressstring1 As String = txtpostcode.Value.Trim()
Dim addressstring() As String = Split("addressstring1", ",", 1)
I'm trying to get the ATM Class to Instantiate on the Form class.
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ISSUE = " 'ThisATM' is used before it has been assigned a value. A Null reference exception could result at runtime"
The Other problem i am having is with a class in the program called CardReader. What am i supposed to type to let the code below be able to "read" the read function on the Form1?
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