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Hi everyone, this was an email to a friend that doesn't seem to be around.. perhaps you guys can help me out here ? I hope the examples I provided are clear enough. I'm having a bit of a problem grapsing the exact concept of what I need to do. An example or point to a good resource would be fantastic!! Thank you all in advance:
---------------------------
public class tbl_someTable {
private string field1;
private string field2;
public string Field1 {
get { return field1; }
set { _field1 = value; }
}
public string Field2 {
get { return field2; }
set { field2 = value; }
}
}
So above is a class, representing a table in my database. Now, think ‘big’ and there are several of these, covering all sorts of tables. Now, I want a ‘storage’ class, which stores information about something that’s currently going on. I create that object, and have it wired with change events..
public partial class StateObject {
[event declarations for an “onStateObjectChanged” event]
private tbl_someTable _someTable;
public tbl_someTable someTable {
get { return _someTable; }
set {
_someTable = value;
onStateObjectChanged(this,new StateObjectEventArgs(“someTable”));
}
}
}
Now, the above works GREAT !!! In usage :
…
StateObject stateObject = new StateObject();
stateObject.StateObjectChanged += delegate ( object S, StateObjectEventArgs E) {
MessageBox.Show(“Called. – “ + E.TableThatCalledMe);
};
stateObject.someTable = new tbl_someTable();
stateObject.someTable.Field1 = “Hello”;
stateObject.someTable.Field2 = “World”;
…
The above, would generate two events! That’s ok, still not optimal.. but whatever. At least I know something changed! I might not want to know that those two fields changed, but what can I do ?
-- NOW – The problem.
public partial class StateObject {
private List<tbl_someothertable> _someOtherTable = new List<tbl_someothertable>();
public List<tbl_someothertable> someOtherTable {
// Get / Set accessors
// No way to fire them!!!
}
}
…
tbl_someOtherTable x = new tbl_someOtherTable();
x.name = "Test 1";
stateObject.someOtherTable.Add(x); // as an example
x = new tbl_someOtherTable();
x.name = "Tets 2";
stateObject.someOtherTable.Add(x);
…
I would get no notifications!
I understand that perhaps I should be using the Collection<t> class instead, because I can override the add/remove/etc. events ? – well, I don’t know how to do that, or implement it in StateObject properly ?
I realize, I’ll probably have to create another class, that inherits from tbl_someOtherTable and implements ICollection<t> ? Then I can get notifications and such, but I’m not sure how to wire them into the original class ? – or just subscribe to them in a constructor or something, and make it fire the main [StateObject] event that notifies other things ? What I really need is an example that doesn’t confuse me! I think I have a pretty good grasp on this… but I’m just not quite there. I need to store a list of objects [think, items in a cart!] and be able to access them easily!
Thank you !
-- modified at 22:16 Saturday 23rd June, 2007
- Matthew
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I need to develop a client-server socket application, where the client will simply send data to a port(No specified IP will be said, may be IPAddress.Any). And the server will grab data from that IP Address and port(So server socket will bind to a specific IP ) and insert the data to database.
This seemed a bit conflicting to normal client-server idea to me and I have developed it the other way(like normally, clients send to the specific IP (of server) and port, and server just listens to a specific port from IPAddress.Any).But now i am instructed to do it reversely as i said above. Can any one tell me how can i do it?
I tried to create a client socket that will send data to IPAddress.Any and a specific port. It gave me exception -
"Only one usage of each socket address (protocol/network address/port) is
normally permitted."
Chayan
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I made a library and used it in an application. But when I moved the application to another directory, one of those windows with the "Send Error Report To Microsoft" thing popped up. So I moved the library to the same directory as the application and it worked fine. Why can't they be in different places?
-----
Note: *** Never give me an answer have anything to do with Visual Studio. I don't have this program, and it'll be that way for a long, long time. ***
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Fundamental design feature of .NET, an assembly looks for references in two locations, firstly it's own directory tree (i.e. the same directory and sub-directories of the directory which the executable is in (hope that makes sense)) and also the GAC. By moving the library away from the application's directory hierarchy the CLR is unable to locate it.
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I guess the real question is, why did you expect it to be otherwise ? .NET assemblies are not registered like COM dlls are, and the system is not going to search the whole HDD for your file. If it did, what would it do if it found more than one of the same name.
As someone else said, the 'new' feature of .NET is to discard the idea of central registry and go back to having all the files local, so each exe has it's own copies of the libraries it needs.
Christian Graus - Microsoft MVP - C++
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
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Hi..
I am making a VS.Net2003 windows application.Iam trying to create a typed dataset without using the usual way (Data menu>generate dataset) because I don't want to create the dataset and fill it in the Form class.So I have added a new dataset visually (Right click the project then Add New Item then choosing DataSet) but when I drag the table to the designer panel of the DataSet XSD file the schema of the table appears but I didn't find any adapters generated.Then I created a SQLDataAdapter to fill the typed dataset and then give it to the datagrid as a datasource but nothing appeared in the datagrid.Iam trying to display 2 columns in the datagrid using DataGridTableStyle(DataGridBoolColumn and DataGridTextBoxColumn).I hope that you can help me to solve this problem.
I am too late but i will never give up
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VS2003 doesn't generate table adapters for your dataset. The only way to get one generated for a specific table, is to create a new component. After you created the component, you need to show the designer of the component and drag-and-drop a data adapter onto the designer. Now you can configure it using the contextmenu.
Of course you can move over to VS2005 or C# 2005 Express edition. This contains the functionality you need and many other things that could make your life easier. However it depends on the requirements you have for the application if changing to C# 2005 is an option.
WM.
What about weapons of mass-construction?
"What? Its an Apple MacBook Pro. They are sexy!" - Paul Watson
My blog
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Thank you very much.I tried it as you told me and it works.I tried to use the same code that was added automatically to fill the dataset from a separated class but it didn't work and I dont know how to save changes in the datagrid to the database because I didn't add an object of the dataset to the designer using the code (adapter1.update(dataset1))?
I am too late but i will never give up
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Hi ,
I want to add a new user account to windows using C#, its a stand alone pc , not on domain , no AD. I found some examples on internet , which uses "Netapi32.dll" , and its not working for me. I cant seem to get error code that why its failing !!!
Is there any .NET API to add user ?
Or any working example of using Netapi32.dll API ?
Thankz
ZINK
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Thanks Giorgi
-- modified at 15:34 Saturday 23rd June, 2007
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I'm trying to learn How to use Databases from a book,it gives me this code to input and it runs fine except it doesn't write any of the lines to the console as it should. I dont get any error messages. I moved some of the code around and the problem seems to be that it stops processing after the conn.Open() method. Anybody know why or how to fix it?
using System;
using System.Data;
using System.Data.SqlClient;
namespace Chapter04
{
class SqlServerProvider
{
static void Main(string[] args)
{
// Set up connection string
string connString = @"
server = .\sqlexpress;
integrated security = true;
database = northwind
";
// Set up query string
string sql = @"
select
*
from
employees
";
// Declare connection and data reader variables
SqlConnection conn = null;
SqlDataReader reader = null;
try
{
// Open connection
conn = new SqlConnection(connString);
conn.Open();
// Execute the query
SqlCommand cmd = new SqlCommand(sql, conn);
reader = cmd.ExecuteReader();
// Display output header
Console.WriteLine(
"This program demonstrates the use of "
+ "the SQL Server Data Provider."
);
Console.WriteLine(
"Querying database {0} with query {1}\n"
, conn.Database
, cmd.CommandText
);
Console.WriteLine("First Name\tLast Name\n");
// Process the result set
while(reader.Read()) {
Console.WriteLine(
"{0} | {1}"
, reader["FirstName"].ToString().PadLeft(10)
, reader[1].ToString().PadLeft(10)
);
}
}
catch (Exception e)
{
Console.WriteLine("Error: " + e);
}
finally
{
// Close connection
reader.Close();
conn.Close();
}
}
}
}
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The code looks fine, how exactly does it stop?
It could be that you are getting time-outs on the connection.
WM.
What about weapons of mass-construction?
"What? Its an Apple MacBook Pro. They are sexy!" - Paul Watson
My blog
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Hello Coders!
appologies if this is in the wrong forum, as it involves C# and XAML. Also, im a noob which cant be helped.
Im attempting to create a viewer application to display information in an XML file.
Whenever i assign data to a class variable, like so:-
PortfolioItem.m_ID = xID.GetAttribute("id")
i get the following error message:-
http://www.klog.co.uk/images/xamlerror.jpg
I have my classes in a separate cs file, and all my coding is being done under the public Window1() method in the windows1.xaml.cs code behind file
any help would be fantastic
Kris
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All that can be devised from that screenshot is that an error occurred when an instance of Window1 was being created. Check throught the construction code etc for anything that'd throw an exception.
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This is a typical case where the inner exception is the only source of information.
Can you try again and check the inner exception of the exception? Usually this gives the real error.
WM.
What about weapons of mass-construction?
"What? Its an Apple MacBook Pro. They are sexy!" - Paul Watson
My blog
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Hi,
I am having some confusion of abstract methods and inheriting.
Lets take my example:
abstract class MyClass
{
public abstract void Method1();
public abstract void Method2();
}
class YourClass : MyClass
{
public override void Method1()
{
// Implementation here
}
public override void Method2()
{
// Implementation here
}
}
Everything I understand till the next part:
MyClass mc = new YourClass();
Why I do not understand it is because if YourClass has extra methods, then how can it save that instance in mc?
Please can someone explain this to me in a little more detail?
Regards
ma se
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ma se wrote: MyClass mc = new YourClass();
Why I do not understand it is because if YourClass has extra methods, then how can it save that instance in mc?
Please can someone explain this to me in a little more detail?
Sure. Classes are reference types. So MyClass mc; only creates "pointer" to MyClass.
new YourClass() creates instance of YourClass somewhere in memory and returns reference (again, think pointer) to to it. It should be clear now that MyClass mc = new YourClass(); does not save instance of YourClass IN mc - it assigns reference to YourClass. That's why it fits.
I am not 100% correct now but you should get the idea.
"Throughout human history, we have been dependent on machines to survive. Fate, it seems, is not without a sense of irony. " - Morpheus
"Real men use mspaint for writing code and notepad for designing graphics." - Anna-Jayne Metcalfe
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Adding to that, you can save a reference to a very specialized thing into
a very dumb thing, so it is perfectly OK (but maybe not very useful) to write:
object myThing=new VerySofisticatedFormWithLotsOfFeatures();
unfortunately you can't do much more to myThing than call its ToString() method;
unless you cast it again as in:
VerySofisticatedFormWithLotsOfFeatures aha=
(VerySofisticatedFormWithLotsOfFeatures)myThing;
aha.NowICanShowOfThoseFancyThings();
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Hello!
How can I determine at runtime if my .NET is running as a Unicode Windows application?
For example, if I run my application on Windows 98, all the window controls are used in ANSI mode. If run on Windows 2000 and higher, the Unicode versions of the window controls are used. Is there a way to see which version is currently used?
Thanks and best regards
Dominik
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You can find out on which OS your application is running by System.OperatingSystem and System.Environment classes
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Dear all,
I have the following code :
private void button2_Click(object sender, EventArgs e)<br />
{<br />
<br />
<br />
NpgsqlConnection conn = new NpgsqlConnection("Server=192.168.24.24;Port=5432;User Id=postgres;Password=S3cr33t;Database=Database;");<br />
<br />
NpgsqlDataAdapter mySqlDataAdapter = new NpgsqlDataAdapter("Select * from points", conn);<br />
DataSet myDataSet = new DataSet();<br />
DataRow myDataRow;<br />
<br />
<br />
NpgsqlCommandBuilder myCommandBuilder = new NpgsqlCommandBuilder(mySqlDataAdapter);<br />
<br />
mySqlDataAdapter.Fill(myDataSet, "points");<br />
myDataRow = myDataSet.Tables["points"].NewRow();<br />
<br />
<br />
myDataSet.Tables["points"].Rows.Add(myDataRow);<br />
<br />
foreach (DataRow myDataRow1 in myDataSet.Tables["points"].Rows)<br />
{<br />
myDataSet.Tables["points"].Rows[0]["track_easting"] = "665544";<br />
}<br />
mySqlDataAdapter.Update(myDataSet, "points");<br />
}
This code 'appears' to run fine. However, if I check back in the database, it has only updated the first row. But I want it to update every single row in the Dataset / Database. So I dreamed up the Foreach statement but I think I'm using it wrong. Can someone point me in the right direction ?
Cheers
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Rick van Woudenberg wrote: myDataSet.Tables["points"].Rows[0]["track_easting"] = "665544";
[0] ?
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Your previous posters point is here!
foreach (DataRow myDataRow1 in myDataSet.Tables["points"].Rows)
{
myDataSet.Tables["points"].Rows[0]["track_easting"] = "665544";
}
You are iterating through all rows, but only updating the first row(ie Rows[0])
try
foreach (DataRow myDataRow1 in myDataSet.Tables["points"].Rows)
{
myDataRow1["track_easting"] = "665544";
}
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Sweet .. that is something that I am going to try. Luc ( in the previous reply ) pointed me in exactly the same direction, So after a little bit of tinkering, I came up with this :
for (int x = 0; x < myDataRow.Table.Rows.Count; x++)<br />
{<br />
myDataSet.Tables["points"].Rows[x]["track_easting"] = "665544";<br />
}
Is there a significant difference between the two ?
Kind regards,
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