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Ok. Thanks for your help 
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In my app I need to come up with a way to differentiate between a database connection error and a database read error. Let me give you an example. Say I have a Class Category with a function GetCategory that returns a category object like this,
Private Function GetCategory(ByVal CategoryID) As Category
Using mycon As New MySqlConnection(My.Settings.Orders)
Dim myCat As New Category
mycon.Open()
'Code to return category her
Return myCat
End Using
End Function
Normally to call this you would have some code like this :
Try
Dim newCategory As Category = GetCategory(myCatID)
Catch ex As MySqlException
'error handling code here
End Try
but if you do it like this then you can't tell whether the exception was caused by a faulty db connection or whether the
exception was thrown in reading the table.
What I have done so far is to create 2 custom exceptions (DBRead and DBOpen Exceptions) and then trap the mysqlexception twice in each routine like this
Private Function GetCategory(ByVal CategoryID) As Category
Dim mycon As New MySqlConnection(My.Settings.Orders)
Try
Dim myCat As New Category
mycon.Open()
Try
'code to get category from db
Catch ex As MySqlException
Throw New DBReadException(ex.Message, ex)
End Try
Return myCat
Catch ex As MySqlException
Throw New DBOpenException(ex.Message, ex)
Finally
If mycon.State = ConnectionState.Open Then
mycon.Close()
End If
End Try
End Function
but this solution seems really klunky and very inelegant, as I would have to trap errors twice in each function as a pose to only when I call the function as in the first example. If someone has a better approach I would really appreciate knowing how you do it.
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I don't know the MySqlException class, but by analogy to SqlException and OracleException, I would guess that there is some sort of error code that you can look at to determine the exact nature of the underlying error. C.f. SqlException.Errors or OracleException.Code. By looking at this you should be able to tell whether it is a read error or not.
As for creating your own exception type, use the same approach: you have one exception, MyDbException, and add a property to that, e.g. MyDbException.ErrorCode where ErrorCode tells you what went wrong (Connect or Read). Then you only have one exception to deal with. There are other advantages to this, for example you are then hiding the dependency on MySql so if you ever do switch to a different database you won't have so much code to rework.
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In the MySqlException Class you have a Number Property that returns an int containting the MySql Error Code (The ErrorCode Property Returns the HResult) but that could be all of nearly 4000 codes, depending on the specific error (i.e 1049 - Unknown Database Error, 1045 - Access Denied Error) and to check for these seems overboard really.
I like your idea of adding a property to my custom exceptions so that in the calling function I only need to trap one error instead of 2, although I can't see it helping me when I trap the original error unless I can get the MySql connector to actually throw my custom exception (impossible ?). I don't really know to be honest, but many thanks for your input.
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Hi All,
Last month I posted this question, but I think I didnt get response for that. Anyways, I would like to ask again:
I am one vb.net windows application installed on my client's PC. Now my client has asked some changes in the code and re-send that application, so that he can uninstall the previous version and install the updated version.
From my end, I have done the requested modification and created a Setup & Deployment project in VS2005.
Now I dont want him to uninstall the previous version of that application installed on his PC. I want to update his installed application with the updated one ( which I made on my PC) without un-installing his last version.
Can someone Pls let me know how to create this? Any patch building is required or not? I am new to this, though i can send him the updated exe so that he can uninstall the previous version and install the new version, but i dont want him to do...I want him to directly update his present verion of the application already installed.
Anyhelp would be appreciated.
Regard,
R.S.
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As far as I know, the Setup and Deployment project doesn't create patches. You can it it to upgrade a previous verison of the package, so long as you have the ProductCode that it used, then the current one will uninstall the old version and install the new one.
I don't use the Setup and Deployment project, so I'm surely no authority on it. I use real setup and deployment tools, such as Wise Package Studio, InnoSetup, and InstallShield.
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Hello to All,
Where are temporary internet files stored in Firefox ? (like IE stores them in temporary internet files).
Thanks
If you can think then I Can.
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To go to the disk cache section , type in:
about:cache?device=disk
in the address bar of FF.
Also have a look at this[^] addon.
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where i can type this .
If you can think then I Can.
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He already told you:
in the address bar of FF.
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How the hell did this question end up in the Visual Basic forum?
I fail to see the link between FF and VB.......am i missing some info here?
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daveauld wrote: am i missing some info here?
Yep, I believe you are; and so am I.
Steve Jowett
-------------------------
Real programmers don't comment their code. If it was hard to write, it should be hard to read.
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I m with ur favor.
If you can think then I Can.
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Hi CP,
I developed an appl. in that i am having controls like textbox, combobox, list box,button ,etc and some other controls from PowerPacks.
I implemented successfully Cut/ Copy / Paste of these controls within the application .
Now i have to implement the things in Clipboard . How can i serialize the class which is maintaining the list of controls.
Public Class Temp
Dim lTempControls As List(Of Object) = Nothing
End Temp
So how can i serialize to clipboard and get all the things when i exit & open the application ?
Regards,
For1206
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The Clipboard is common across the system, you interact with the clipboard through the MyComputer.Clipboard object.
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You beat me to it!
------------------------------------
I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave
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Yeh, but notice we both got voted 1.
Now was that because the suggestions weren't an acceptable answer for the OP, or did someone else think we were taking the pi$$.
Guess we will never know!
Do you want a 5 exchange?
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I will 5 you all the way down, just to be sure!
------------------------------------
I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave
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Use My.Computer.Clipboard
This may help[^]
------------------------------------
I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave
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Hi Dave,
These things doesn't workout for me . Bcoz i implemented my custom way to build the application .
Clipboard Serializable format but it's not working.
Regards,
For1206
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Ah, sorry then, I cannot help further.
But do be careful and think before doing!!!
------------------------------------
I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave
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for1206 wrote: So how can i serialize to clipboard
Don't! Remember the clipboard is a user controlled mechanism. If you serialize to the clipboard and the application then terminates you have lost control of the clipboard, and potentially all your objects. Serialization should be to permanent storage, e.g. disk files.
MVP 2010 - are they mad?
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Like Richard said, you copy to/paste from the Clipboard, in whatever format suits your app (text, image, file list, ...); and you serialize to/from permanent storage in some format (binary, XML, ...) to make your object persistent. Those are two distinct mechanisms with different purposes.
Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]
I only read code that is properly formatted, adding PRE tags is the easiest way to obtain that. [The QA section does it automatically now, I hope we soon get it on regular forums as well]
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Hi friends,
I want to develop a small Application.
In Brief a scanned Paper which is of four A4 Pages.
It contains image and at the bottom contains many fields.
SO that I have to develop a application.
The Image size is too large. SO, I would like to apply scrolling for ImageBox.
and How to make active of the next item..
Please let me know.
Thanks
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