Utilize Classes That Inherit The System.Data Name Space?
Mar 9, 2009
I would like to utilize classes that inherit the System.Data name space.Specifically, I would like to have classes CarColumn, CarTable, and CarSet derived from DataColumn, DataTable, and Dataset respectively.I would like to be able to add additional properities to each class. As an example this is how I would like to reference items within the classes:
CarSet.CarTable(0).Columns(0).foo
CarSet.CarTable(0).bar
I know that VB.Net is not capable of Multi-Inheritance.
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Oct 18, 2009
I am trying to inherit System.Data, but when I use Inherits System.Data I get a "Type Expected" error. Is there a way to do this? or is the question I have been given meant to make me realise that it can not be done?
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Oct 20, 2010
I have classes setup similar to this:
<DataContract()> _
Public MustInherit Class SystemTaskProcessBase
Public MustOverride ReadOnly Property Name() As String
Public MustOverride ReadOnly Property Description() As String
Public MustOverride Property Result() As SystemTaskResult
[Code]...
I need to use these classes on the client system, but also need to be able to create these "tasks" through a management interface. Each class (Task) that inherits the base, could have its own properties that are unique to each class, but at the same time, share the same common base class properties. For example, the above shows a reboot task and a delete file task, the delete file task needs to know which file to delete, so has a property for that. But the reboot task does not need this property. So when the management application is creating these tasks, it shouldn't provide a text box for the file property for the reboot task. There may be more tasks created at a later date with completely different properties.
How would I go about providing the WinForms management application a way to enumerate each class into a ListView for example, and allowing the user to create these tasks and filling in the dynamic properties that each class would have? Desired functionality would be to create a task form that creates dynamic controls available for the properties as needed, depending on the public properties in each class, but at the same time have the base class properties available as well.
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Oct 15, 2011
I am cleaning up some code and I have multiple classes that are 99% exactly the same. So my understanding is that my options are...
1. Create a class and all other classes inherit from it and modify it a bit
2. Create an abstract class and all classes inherit from it and modify a bit ** I took this route
3. Create an interface and all classes Implement that interface.
Here is my 'original' class below (the one that all of them look 99% identical). This class is used in an arraylist so I have a listing of all my images from a folder I have searched.
[Code]...
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Jan 20, 2012
Since most of the projects I work on are exclusively SQL Server 2005/2008 database driver, I was wondering about the implications of using System.Data.SqlTypes classes as data types in my VB.Net Framework 4.0 code.For example currently I define integer variables as Dim X as Integer.Using System.Data.SqlType classes I would define my intege variables as.Dim X as System.Data.SqlTypes.SqlInt32 implications for performance, serialization and databinding. One difference would be that all variables would default to Null.
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Apr 8, 2010
I am new to .NET with Java back ground. Got a question on name space. I believe they are synonymous to Java packages concept.If I need two classes in the same name space do I have to declare the name space in both the classes?. Both classes are in different files E.g: If Class1 and Class2 need to be in Namespace myspace. Should it be
[Code]...
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Sep 15, 2009
I have written methods to override the LoadPageStateFromPersistenceMedium and SavePageStateToPersistenceMedium methods. now the problem is that i am using a masterpage, so how do i maintain using my masterpage and still inherit from System.Web.UI.Page?
Bear in mind that the .vb Code behind the masterpage already inherits System.Web.UI.MasterPage. Anybody know how i can "properly" override these methods in a MasterPage?
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Jan 16, 2010
Is the only way to create custom exceptions to inherit from System.Exception?
I wish to create a class that can be thrown as an exception but i do not wish to inherit from System.Exception because i have a base [Object] class in my library which all my classes should inherit from and i wish my custom exception class could also inherit from it.
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May 30, 2011
How to create a class which inherits from a data type, specifically from Char data type? I just want to add one property to it. If it's not possible, are there any other ways to accomplish this?
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Apr 8, 2010
I have the below lines of code :I am getting the error as mentioned in the Title above.This error has come after converting a C# Code to VB.NET Code which is mentioned below:
C#:
public override IChannelListener<TChannel> BuildChannelListener<TChannel>(BindingContext context)
{
if (context == null)
[code]....
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Jan 15, 2010
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
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Sep 25, 2011
How would i get a certain text inside a textbox to equal that text space to space or null to space?
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If Textbox1.Text.StartsWith(Textbox2.Text + " ") And Not String.IsNullOrEmpty(Textbox2.Text) Then
Textbox1.Text = Textbox1.Text.Remove(0, Textbox2.TextLength)
Textbox3.AppendText("a")
End If
Btw: after i finish this step my project will be finished!
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Feb 2, 2012
I get an error when I try to build my project.'SSLAccessFiltercannot' be used as an attribute because it does not inherit from 'System.Attribute'. [code]
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Feb 29, 2012
I remember seeing somewhere on the net that there are classes in .Net that will return information about your computer. I know that System.Environment returns some of this information like MachineName and some other stuff. Are there other classes that will return information such as hard drive size, free and used space, total memory, used memory?
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Nov 17, 2009
I need to generate a class at runtime similar to System.Resources where you can add a resource eg 'picture.bmp' and it immediatelly is accessible as 'System.Resources.picture.bmp'. I presume I need to generate XLM or/and XLSD at design time and then deserialise at runtime but I cant find a reference on how to do this. Specially without knowing the generic class in advance (as 'System.Resources' doesnt know all the resources in advance).
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Jul 31, 2009
I am fresher in vb.net but I want to develop a project in this case I want to use the system.Configuration namespace's specific calsses. But I am not clear which class i use and why it's function and it's use.
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Sep 2, 2011
I've spent a substantial amount of time trying to figure this out, but I keep getting the same error
A first chance exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll
A first chance exception of type 'System.NullReferenceException' occurred in project1.exe
This happens when I try to use the DataReader.my code is
Public Function Identification() As List(Of Integer)
Dim returnIndex As New List(Of Integer)
Dim dbCount As String = "SELECT Bookingid FROM bookdetail WHERE Date =" & getCurrentTimeString() & " 12:00:00 a.m."
Dim count As Integer = 0
[code]....
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Aug 28, 2009
I have been developing some components for our products at work, and one of them is based off the flow layout panel.What i would like to do is provide a custom designer for it, but without loosing the features provided by it's default designer (System.Windows.Forms.Design.FlowLayoutPanelDesigner) which is marked as internal.Using Reflector i thought i would just implement it again myself, seeing as it inherits from 'FlowPanelDesigner and that from PanelDesigner` all of which are internal.
Why would these classes be specifically marked as internal? Is it due to them being specifically for Visual Studio use, and thus not 'framework' code?Also, is there an easier option that re-implementing all the functionality?
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Feb 28, 2010
My software handles multiple operations on files, and I have now finished writing the related functions, using the System.IO classes. I now need to add support for network drives. Using a mapping works very well (although Directory.GetFiles is a bit low, and I don't know why), but I'd now like to be able to deal directly with paths such as \192.168.0.10Shared FolderMyDrive. Is there any way to handle this type of paths other than mounting the drive to an available drive letter, using the newly generated path, and then unmounting?
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May 5, 2010
Exists a good tutorial or example that shows how to use these classes from namespace System.Drawing.Imaging.
My idea is, to produce Bitmaps and to compress them. I don't know if for my case IO Streaming is important because I don't want to save the bitmap on my hard disk.
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Sep 4, 2011
i need to clear this error
A first chance exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll
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Jan 22, 2009
I am just trying to get the system to open a database and I get this error:
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
here's the entire code of the main form
=======================================
Imports System
Imports System.Data
Imports System.Data.SqlClient
[code]....
the error is generated at the open method note* this same code works fine in another computer, the main difference is that this one has a 64 bit OS.
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Jan 26, 2009
i am trying to connect to an MS Access database and I am getting an erro message on the following line of
searchtable_command = New SqlClient.SqlCommand(searchtable_string, testsearch_connection)
Error:'System.Data.Odbc.OdbcConnection' cannot be converted to 'System.Data.SqlClient.SqlConnection'.
Here my connection string:
Dim testsearch_connection As New Odbc.OdbcConnection("Provider=MSDASQL;Driver={Microsoft Access Driver (*.mdb)};Dbq=C:CesarAccessdatabase.mdb;Uid=admin;Pwd=;")
What am I missing?
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Jul 9, 2010
I Have just been watching a video on throwing Exceptions. Are you supposed to throw System.Exceptions from within your custom classes. to the calling code, Which other way can they communicate. I have read in several places it is bad practice to throw SystemExeptions.
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Jul 7, 2010
For my applications I use the following class:
Imports System.Security.Cryptography
Imports System.IO
Imports System.Text
'SymmCrypto is a wrapper of System.Security.Cryptography.SymmetricAlgorithm
[code]....
Most of the time this works as it should, but sometimes it encodes a string and the gives an error on decoding it. The error message is: Invalid length for a Base-64 char array.
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Jul 7, 2009
WHERE the values for intellisense and namespace/class/member completion works. I figured if I can drill into where/how it is deriving that data I can try to reconfigure my project so that it will resolve my namespaces correctly.
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Jul 28, 2009
I had the following code to retrieve the data from database:
[Code]...
But from the database, it looks nicely and align nicely.For example, all the amount will align nicely to the header "Amount". May I know is there any solution to make sure that the data that display on the web follow the alignment from database?Because in the database, the data is separate nicely with space and align nicely.Actually the above data are all store in the same column in database. How can I make sure the data being retrieve follow the alignment of database?
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Feb 20, 2012
I'm having the reverse problem as this thread.We save off data in several formats, one of which is .XLS, however, some users may not have MS Office installed already, so I want to allow them to use the OS's "open with" dialog to associate with notepad or something so they can open the file.[code]...
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Jun 8, 2010
I have a messagebox with a "yes" and "no" buttons. I am asking the user upon "exit" (ing) the app, if they haved saved their work. The default button is defaultbutton2 "no" and it saves the file. If user selects "yes" they have saved their work, then I need the app to close.Here's the code:
'show messagebox to save work....default button2 = 'no' then saves file....default button1 'yes' is spose to close app
MessageBox.Show(
"Have you saved your work?",
"Garman Music Pro", MessageBoxButtons.YesNo, MessageBoxIcon.Question, MessageBoxDefaultButton.Button2, 0, HelpButton)
If MessageBoxDefaultButton.Button2 = MessageBoxDefaultButton.Button2
Then[code].........
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Oct 15, 2011
I seem to be having a problem with controls that I am creating as new classes (not UserControls) inheriting from an existing system control. Everything seems ok while I create the control code, through to the compile (which is successful and adds the control to the toolbox) and dragging the control from the toolbox to the GUI surface. However, when I then debug or compile the project, I get a message such
[Code]...
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