different behaviour design time / run time

different behaviour design time / run time

Post by ZU1LY » Wed, 12 May 2004 15:41:04

Hi Code guru's

I have created a user control which has access, and thus makes use of a shared singleton class like:
Dim MyAppSettings As DLAppSettings = DLAppSettings.GetAppSettings

This singleton class has amongst other stuff the following line of code in it:
Private m_DL_DBPath As String = System.Configuration.ConfigurationSettings.AppSettings("DMDatabasePath")

As you guess, it must read a string containing the path. Based on this string, a connection string is build later in the code.

Now the control is placed onto a form, and when I open the form (in design time) in the editor, it seems code is executed. And the code fails because the m_DL_DBPath variable has the value nothing.

Yet everything works as it is supposed to be when compiling and running the code.

1) Why is code executing in the designer when I throw user controls on a form?
2) Does System.Configuration.ConfigurationSettings.AppSettings work in design time?

Help is much appreciated as I am already hammering for three days on this.


different behaviour design time / run time

Post by timhuan » Thu, 13 May 2004 12:33:04

Hello eMKa,

Thanks for your post. As I understand, the problem you are facing is that
your application works when running without de *** , while it fails when
starting from VS .NET. Please correct me if there is any misunderstanding.
I think more information is needed before moving forward:

Where does your config file locate, the projects' folder?
Could you post a simple project which is able to reproduce the problem?

I look forward to hearing from you.


Microsoft Online Partner Support

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different behaviour design time / run time

Post by TWFydGluIC » Thu, 13 May 2004 16:16:02

Dear HuangTM,

No, that's not exactly correct.
My program runs correctly if compiled and executed outside VS
But it also runs fine when being debugged in VS.
The strange thing is that when I open a form in the editor which contains the user control, then code seems executed (no idea why!) I ams sure because I put msgboxes in the code, and they are appearing, hence code is being executed.

I am trying to reproduce the problem in a small project, because the current project is big and complex.

different behaviour design time / run time

Post by v-yi » Sat, 29 May 2004 19:16:49

Hi ,

Since this issue is closly related to winform design time behavior, Tim has
transferred this issue to me. I'd like to confirm if I have understood your
scenario correctly.
You have a component which in its constructor will read
ConfigurationSettings.AppSettings collection to get the path setting from a
.config file. the path setting could be get correctly in run-time
regardless in or not in the de *** , however you could not get the value
if put the component onto form in design-time. If there is any
mis-understanding, please feel free to correct me.

I could reproduce the behavior described above on my system, after some
investigation, I found this is because the .NET configuration system always
try to load the .config file with the same name as the executable name
from the Application Base, when the component are created in design-time,
it's actually running in the AppDomain of Vs.NET IDE, so that it tries to
retrieve the corresponding data from
here, the Application Base is where the app start from
and the entry assembly name is devenv.exe
Of course by default devenv.exe.config does not contain "appSettings"
section and your settings, that's why you could not get the corresponding

Does it answer your question?
If you have anything unclear about my reply, please feel free to reply this

By the way, we have a special group for design-time programming in windows
forms, you may post design-time issues to that group next time.


Best regards,

Ying-Shen Yu [MSFT]
Microsoft Community Support
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different behaviour design time / run time

Post by TWFydGl » Wed, 02 Jun 2004 22:01:02

Dear Ying-Shen Yu and Tim

Thanks for explaining this. It is perfectly clear answer. I expected that the config file would be (temporarily) copied to that directory automatically. Also I have been experimenting with copying the config file to the bin directory, but that did not help either, so I got confused and wanted to know what was going on. I will try copying it to the right spot tomorrow. This issue should be resolved then

Thanks again


different behaviour design time / run time

Post by TWFydGl » Thu, 03 Jun 2004 17:56:05

Dear Ying-Shen and Ti

OK, I can confirm that putting the information in the devenv.exe.config does indeed work
This is of course not a "good programming practice" and a potentially confusing solution. It is something that could be improved in the next version of Visual Studio. E.g. it would be better if the application's own config file was copied to this location during design time.

Thanks again for explaining this feature