C# Discussion Boards - CodeProject

Re: Base class method call ?

2-Aug-05 2:13

You can't, and it would suck if you could. Looks like C should derive from A.

Christian Graus - Microsoft MVP - C++

chettu2-Aug-05 2:34

chettu

2-Aug-05 2:34

Why would it suck.. i have a case where Class C should inherit Class B and not A isn't this a possible scenario... i guess so....The possible solution i have done is have a method in class B which will call the base method in A. This scenario will hold in events.. where calling the base class is mandatory....

Re: Base class method call ?

Christian Graus2-Aug-05 14:09

Problem with PrintPreviewDialog

2-Aug-05 14:09

chettu wrote:
i have a case where Class C should inherit Class B and not A isn't this a possible scenario

No, because if inheritance is optional, how could you count on it in any way ?

Christian Graus - Microsoft MVP - C++

kbalias1-Aug-05 19:21

kbalias

1-Aug-05 19:21

Hi
This is for a windows application in C#. I am using a PrintDialog and a PrintPreviewDialog. When I go through the PrintDialog my document prints correctly. When I use the PrintPreviewDialog the preview is correct. However when I click the print icon on the Preview dialog the printer only pushes out a blank paper. Is there anything that I need to specify in the PrintPreviewDialog?

Thanks

Kobus

Re: Problem with PrintPreviewDialog

Alomgir Miah2-Aug-05 3:12

Alomgir Miah

2-Aug-05 3:12

You are not setting the Document property of the PrintPreviewDialog for sure. Please check.

Live Life King Size
Alomgir Miah

sql ce Database problem help me........

limxiuyao1-Aug-05 18:51

limxiuyao

1-Aug-05 18:51

i am using remote data access for my project. this is my code.

private void button2_Click(object sender, System.EventArgs e)
{

SqlCeConnection cn = null;
SqlCeRemoteDataAccess rda= null;
SqlCeEngine sqlEngine=null;
try
{
button2.Enabled=false;
//Create database if it doesn't already exist
if(!File.Exists("\\My Documents\\Student.sdf"))
{
sqlEngine=new SqlCeEngine( );
sqlEngine.LocalConnectionString="Data Source=\\My Documents\\"+
"Student.sdf;"+
"Password= ;"+
"Encrypt Database=True";
sqlEngine.CreateDatabase();
sqlEngine.Dispose();
}

else
{
//open the connection to the database
cn=new SqlCeConnection("Data Source=\\My Documents\\"+
"Student.sdf; Password=");
cn.Open();
SqlCeCommand cmd=cn.CreateCommand();
//drop table tutorial1_Classlist
cmd.CommandText="DROP TABLE tutorial1Class_list";
cmd.ExecuteNonQuery();

//close the conection
if(cn.State!=ConnectionState.Closed)
{
cn.Close();
}
}
//Instantiate the RDA Object
rda=new SqlCeRemoteDataAccess();
//Connection String to the Sql Server
string remoteConnectString="Provider=SQLOLEDB;"+
"Data Source=IT768P27;"+
"Initial Catalog=Student;"+
"User Id=sa;" +
"Password=";// empty password
rda.InternetLogin="";
rda.InternetPassword="";
rda.InternetUrl="http://IT768P27/StudentRDA/sscesa20.dll";
rda.LocalConnectionString="Data Source=\\My Documents\\"+
"Student.sdf;"+
"SSCE:Database Password=";

rda.Pull("tutorial1Class_list", "Select * from tutorial1Class_list",
remoteConnectString,RdaTrackOption.TrackingOn);
}
catch(SqlCeException sqlex)
{
foreach(SqlCeError sqlError in sqlex.Errors)
{
MessageBox.Show(sqlError.Message,"Error");
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message,"error");
}
finally
{
rda.Dispose();
button2.Enabled=true;

}

}

when i run it in my pocketpc ,it give me error like "sql server ce encountered problems in creating the sql server ce database[...connection string..]..
what should i do.. i c every codeing is all right. can u tell me what is wrong with my connection string?

Re: sql ce Database problem help me........

LongRange.Shooter20-Jan-06 6:32

LongRange.Shooter

20-Jan-06 6:32

I see that no one ever replied to this....I hope you found the answer!

But if not...the RDA connection expects IIS at the receiving end. //MyDocuments// is not a well-formed URL for going to a web server.

However if you have IIS running then at a minumum your web would be something like:

"http://myMachineName/SqlHost" assuming your RDA host connection
is in the web SqlHost.

So you need your host name and web name for a well structured IIS connect to your database.

There are 10 kinds of people in the world.

Those that read binary...

...and those who don't.

How can I..

KORCARI1-Aug-05 17:57

KORCARI

1-Aug-05 17:57

Hi.I need to work with Calendar Control .Can you show me where can I find any good tutorials or examples on this topic .Thank you

Re: How can I..

Christian Graus1-Aug-05 18:28

1-Aug-05 18:28

I would suggest that you got voted a 1 for two reasons

1. 'How can I' is not a decent way to head your question, I thought you'd posted the same question twice

2. Google will answer both of these questions in seconds.

Christian Graus - Microsoft MVP - C++

How can I..

KORCARI1-Aug-05 17:55

KORCARI

1-Aug-05 17:55

Hi.Can you show me any tutorial about editing the information of a database which is shown in datagrid.I need to add ,delete,update information interacting only with the grid.Thank you

DropDownList

tatchung1-Aug-05 17:50

1-Aug-05 17:50

Hi!

Im making a form which displays data on a datagrid when i select an item from my dropdownlist. Now my problem is nothing shows up when i choose from my dropdownlist. can someone please check and see if my code is correct because it builds perfectly infact it shows the header but leaves the rest of my queries. Here's parts of the code assuming that my sql queries are correct which i've great confidence that the are:

<br />
//part of the page load member<br />
DataSet dsCompany = new DataSet();<br />
dsCompany = objComp.fGet_Company();<br />
ddlcomp.DataSource = dsCompany;<br />
ddlcomp.DataTextField = "comp_code";<br />
ddlcomp.DataValueField = "comp_desc";<br />
ddlcomp.DataBind();<br />
ddlcomp.Items.Insert(0,"");<br />
<br />
Session["Comp"] = ddlcomp.SelectedItem.Value;<br />
Session["CompName"] = ddlcomp.SelectedItem.Text;<br />
<br />
if (Session["Comp"].ToString() != "")<br />
{<br />
ddlcomp.Items.FindByValue(Session["Comp"].ToString()).Selected = true;    <br />
}<br />

<br />
private void ddlcomp_SelectedIndexChanged(object sender, System.EventArgs e)<br />
{<br />
DataSet dsCol = new DataSet();<br />
dsCol = objCol.GetByClient(ddlcomp.SelectedItem.Value);<br />
<br />
Session["dstSort"] = dsCol;<br />
Session["dtvwSort"] = dsCol.Tables[0].DefaultView;<br />
dgdGrid.DataSource = dsCol;<br />
dgdGrid.DataBind();<br />
}<br />

so...anything wrong with this?
thanx for all your comments, suggestions and reactions!

Kampai!!!

Christian Graus1-Aug-05 18:33

1-Aug-05 18:33

tatchung wrote:
because it builds perfectly

So what ?

tatchung wrote:
DataSet dsCompany = new DataSet();
dsCompany = objComp.fGet_Company();

this is dumb - the new dataset you created will now go into the queue for garbage collection, as you replaced it righ away with the result of this call.

tatchung wrote:
ddlcomp.DataSource = dsCompany;
ddlcomp.DataTextField = "comp_code";
ddlcomp.DataValueField = "comp_desc";
ddlcomp.DataBind();
ddlcomp.Items.Insert(0,"");

None of this is in a !IsPOstback block, so it binds every time, and your selection is lost.

tatchung wrote:
Session["Comp"] = ddlcomp.SelectedItem.Value;
Session["CompName"] = ddlcomp.SelectedItem.Text;

These will always be the first item in the list, as you just did a databind and an insert.

tatchung wrote:
dsCol = objCol.GetByClient(ddlcomp.SelectedItem.Value);

Events fire after page load and before prerender. Not knowing where you did the above, I have no idea what the SelectedItem could be at this stage.

tatchung wrote:
DataSet dsCol = new DataSet();
dsCol = objCol.GetByClient(ddlcomp.SelectedItem.Value);

Waste of memory again.

tatchung wrote:
Session["dtvwSort"] = dsCol.Tables[0].DefaultView;

You're shoving a whole table into the session ? You seem to be using session state a lot, is all of this stuff needed on other pages ? AND you shove it in twice, as dstSort and dtvwSort. This is not ASP. Why do you need this information in the session ?

tatchung wrote:
so...anything wrong with this?

The lack of an !IsPOstback is probably your core problem.

Christian Graus - Microsoft MVP - C++

tatchung1-Aug-05 19:23

1-Aug-05 19:23

Like I said its only part of the code. Sori i couldn't post every part of the form its too long. I've an !IsPostBack right below my Page_Load member along with my "pop-up window" code. Oops! I forgot to mention that this form links to a pop-up window...my bad Blush | :O

. Ohe yeah the datasets created was meant to draw the data from a class i've made in another form. Darn me for skipping too many information.

Ok so here's the deal this form generates data from a database when i fire the dropdownlist. Along with the results it should display 2 buttons for each row; edit and delete. Now when I click the edit button it redirects to my pop-up window and delete...well it deletes the entire row it is aligned with. Back to my first thread...nothing seems to appear when i choose from my dropdownlist except the headers.

I appologize for any misinformation or rather for lack of information. All your replies are greatly appreciated! Thanx for all your assistance!

Kampai!!!

Christian Graus2-Aug-05 2:07

2-Aug-05 2:07

tatchung wrote:
I've an !IsPostBack right below my Page_Load member along with my "pop-up window" code.

So the Data binding code is in an !IsPostback block ?

tatchung wrote:
Ohe yeah the datasets created was meant to draw the data from a class i've made in another form. Darn me for skipping too many information.

But why are you stuffing them into the session, and duplicating info into the session ?

I still think nothing appears because you're resetting your data source. Have you stepped through the code in debug mode ?

Christian Graus - Microsoft MVP - C++

tatchung2-Aug-05 15:22

2-Aug-05 15:22

Oops...I got it. I've inverted the dropdownlist DataTextField and the DatValueField in my SelectedIndexChange method. Sori for bothering you Chris but I've got another question about row deletion. If you could just please check the recent post I've made a new thread. Thanx so much! Your help is invaluable

Kampai!!!

Christian Graus2-Aug-05 15:30

2-Aug-05 15:30

We never addressed why you're stuffing all this stuff in the session.....

I think I read the other question and asked to see the code.

Christian Graus - Microsoft MVP - C++

tatchung2-Aug-05 15:39

2-Aug-05 15:39

Nah its a new thread. Well I was under the impression that sessions where meant to keep data to be passed to another form. I got it from another form which does almost the same thing that my form does. Semi-plagarism but I was totaly cluless when I started this project and i was under intense time constraints

Christian Graus2-Aug-05 16:01

Re: Multi- threads problem

2-Aug-05 16:01

tatchung wrote:
Nah its a new thread.

Answered.

tatchung wrote:
Well I was under the impression that sessions where meant to keep data to be passed to another form.

But why are you passing a dataset to another form, AND a view you can derive from that dataset ? Isn't that expensive ? Why can't you just pass the info needed to get that data from your data layer ?

tatchung wrote:
Semi-plagarism but I was totaly cluless when I started this project and i was under intense time constraints

Why are you on a project at all, if you don't know what you're doing ? Seriously, there's nothing wrong with being a beginner, but a project with time constraints is not the place to do it.

Christian Graus - Microsoft MVP - C++

Multi- threads problem

ppp0011-Aug-05 17:50

ppp001

1-Aug-05 17:50

Thanks for your reply.

Hi,

I have problems in using multi-threading.

What I want to do is as follow,

1. The main thread running the main window GUI as window form
which can accept user input all the time.
2. The second thread running some task,
and after the task is finished, the thread need to ask
main window form(controlled by the main thread) to display some
child window. But I find that the child window will not function
properly as two threads try to control the same GUI at the same time.
So I want to pass the control from the second thread to the main thread
and let the main thread open the child window itself.

Then how can I do that ? I don't want to use Thread.Join since the main thread need to run all the time and cannot be blocked.

Thanks

Robert Rohde1-Aug-05 19:08

Robert Rohde

1-Aug-05 19:08

You shouldn`t create the new window in the separate thread. Give your main form a function which gets all info needed to create the child window and then call this function from your worker thread by calling Invoke with the new function on the main form. Invoke will transfer the call from any thread into the GUI thread.
All GUI related things should be done in one thread.

DDE in longhorn

ppp0011-Aug-05 16:24

ppp001

1-Aug-05 16:24

Hi,

Do anyone know will DDE(dynamic data exchange) still be supported
in window longhorn ?

Thank

Christian Graus1-Aug-05 16:29

1-Aug-05 16:29

I can't imagine why not.

Christian Graus - Microsoft MVP - C++

ppp0011-Aug-05 17:35

ppp001

1-Aug-05 17:35

Coz there are always articles saying that DDE is dead,
or just a residue from early window os. So I just afraid
it will be eliminated from future window version.

Christian Graus1-Aug-05 17:37

1-Aug-05 17:37

COM is, to all extents, dead. But I'm sure the OS will support it, forever. Why make a ton of old code not run anymore, for no good reason ?

Christian Graus - Microsoft MVP - C++