Re: usercontrol - C# Discussion Boards

Re: Console application screen divided in 2 parts

12-Nov-09 12:19

The only way I know to do this, is to store the details of your two parts, and render the whole screen again every time something changes.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

Shameel12-Nov-09 22:31

Shameel

12-Nov-09 22:31

This is not going to be that easy with .NET. I used to work on such things long ago using FoxPro Smile | :)

Remoting Events fail if network not connected until after app starts

John Whitmire12-Nov-09 11:11

John Whitmire

12-Nov-09 11:11

The scenario: Peer-to-peer network through a switch; no DNS, all fixed addresses. Main app establishes a remoting connection (Activator.GetObject) to a marshalled singleton object in a service on another machine. The app reads properties and invokes methods on the remote object. It also subscribes, through a wrapper, to events raised by the remote object. Remoting is configured in the config file on both ends.

What works: All actions initiated by the app. Also, by monitoring the periodic events from the remote object, the app detects loss of connection (whether from physical disconnect or termination of the remote object) and will automatically recover when the object again becomes available. This has been extensively exercised.

What fails: If the app's host machine is not physically connected to the switch until after the app starts, the event subscriptions fail to work. The app gets no notice of this. The remote object gets a "connection actively refused" exception when it invokes the event delegate. WTF | :WTF:

Already tried: Delaying instantiation of the event wrapper until after the first time the remote host could be successfully pinged. No change.

Please note: EVERYTHING works great as long as the network cable was connected at the time the app was started. All events are properly delivered and all subsequent disconnects are appropriately handled with successful recovery upon reconnect. The only known difference between the working and non-working scenarios is WHEN the network cable was connected to the switch: before or after the app starts.

I'm at a loss for where to look next. Confused | :confused:

What am I missing? (Also, should I cross-post this to the .NET Framework forum?)

usercontrol

farokhian12-Nov-09 9:48

12-Nov-09 9:48

Hi I create a windows form control library and use it in my forms;
I want to transfer a variable from my component to my code in form;
How can i do it?

Christian Graus12-Nov-09 10:20

12-Nov-09 10:20

This is a pretty basic question. How did you create a form control library ?

You can expose values as properties and read them in your form. Or you can expose a delegate that fires when a value is changed.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

farokhian12-Nov-09 10:28

12-Nov-09 10:28

I crete form control library like other !
Is it a hard job?!

Christian Graus12-Nov-09 10:42

12-Nov-09 10:42

farokhian wrote:
Is it a hard job?!

It requires you to write a line or two of code. If you don't know how to create a property ( let alone a delegate ), then I would suggest you buy a basic C# book and read it. I assume this is for a class, or you are teaching yourself. You can't possibly be a paid programmer ? Just buy a book and work through it, don't worry about class libraries if you don't even know basic C#.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

farokhian12-Nov-09 10:56

12-Nov-09 10:56

I am teaching my self;
And i create properties and my problem was solved.
I don't think these things are so hard to learn ?!
This is the simple property that i create :
public string TxtBoxId
{
get
{
return text;
}
set
{
text = value;
}

}

Anyway THX.

Christian Graus12-Nov-09 10:59

12-Nov-09 10:59

Yes, that's all you need. What I am trying to say is, if you want to learn, buy a book to learn these sort of basics, otherwise there will always be holes in what you know, in terms of the fundamentals.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

farokhian12-Nov-09 11:06

12-Nov-09 11:06

Thanks alot for your suggestion .
Be sure that i do your suggetion.

Good Luck

Christian Graus12-Nov-09 11:15

How can I check if a table exists?

12-Nov-09 11:15

I hope so. I've urged you to buy a basic book before, and you plainly have not done it.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

Emmet_Brown12-Nov-09 9:24

12-Nov-09 9:24

can anyone help?

I tried to google out the solution but none of the answers I found was non proper for C#.

I've a MS SQL Database (Compact Edition(this is not an issue here))

I want to check if a table exists, what should I do?

I found an SQL statement for this

IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[TableName]') AND type in (N'U'))

but I could not figure out how to use this in C#

My first idea is=

string command2 = "IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[TableName]') AND type in (N'U'))"
SqlCeCommand com2 = new SqlCeCommand(command2, conn);

Where should I look if it returned 1 or 0?

Christian Graus12-Nov-09 9:32

12-Nov-09 9:32

SQLCe will not support [dbo]. at the head of a table name. I don't know if it supports this sort of call ( I've never tried it ). Remove the [dbo]. and then complete the statement ( such as if EXISTS... select 1 ELSE select 0 ) then you can execute scalar and see if you get 1 or 0 back. You can experiment inside SQL Server management console to establish exactly what SQL works.

Your alternative is to say select * from tablename and do it in a try catch to see if it blows up ( presumably b/c the table does not exist )

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

Emmet_Brown12-Nov-09 9:36

12-Nov-09 9:36

thanks I'll try

furthermore, just to know

Can I use this "if -> else" format like below?

IF (blahblahblah) >0 BEGIN CREATE TABLE MyTable (...etc) END"

Christian Graus12-Nov-09 9:42

12-Nov-09 9:42

I think so. I've never executed SQL that complex outside of a proc, but I don't see why you shouldn't be able to.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

Emmet_Brown12-Nov-09 9:50

12-Nov-09 9:50

according to compiler
Compact Edition does not support the function OBJECT_ID()
I guess try-catch is the only solution
is it?

Christian Graus12-Nov-09 10:43

12-Nov-09 10:43

I would presume so. I am not surprised, CE is a very cut down version, designed to be portable, not complete.

Christian Graus

Driven to the arms of OSX by Vista.

Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.

The Man from U.N.C.L.E.12-Nov-09 9:36

The Man from U.N.C.L.E.

12-Nov-09 9:36

Just execute the command, but a better command would be

string command2 = "Select Case OBJECT_ID('TableName') when null then 0 else 1 end;";
SqlCeCommand com2 = new SqlCeCommand(command2, conn);
bool tableExists = (bool)com2.ExecuteScalar();

If you have knowledge, let others light their candles at it.
Margaret Fuller (1810 - 1850)
www.JacksonSoft.co.uk

Emmet_Brown12-Nov-09 9:39

12-Nov-09 9:39

oh this works?
I'll try right now Big Grin | :-D

Emmet_Brown12-Nov-09 9:47

12-Nov-09 9:47

The function is not recognized by SQL Server Compact Edition. [ Name of function = OBJECT_ID,Data type (if known) = ]

..it says

pointing out the

bool tableExists = (bool)com2.ExecuteScalar();

line :/

The Man from U.N.C.L.E.12-Nov-09 10:48

The Man from U.N.C.L.E.

12-Nov-09 10:48

SQL CE. silly me.

string command2 = "SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = 'your table name'";
SqlCeCommand com2 = new SqlCeCommand(command2, conn);
bool tableExists = false;
If ((Integer)com2.ExecuteNonQuery() > 0){
   tableExists = true;
}

ExecuteNonQuery returns the number of rows selected and if the table exists the return value will be 1.

If you have knowledge, let others light their candles at it.
Margaret Fuller (1810 - 1850)
www.JacksonSoft.co.uk

Emmet_Brown12-Nov-09 10:56

12-Nov-09 10:56

oh thanks =)