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Hello,
Is "response" a string?
Does youre DelA have an string parameter too?
Martin
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Hi,
Yes on both questions.
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Hello,
Could you post the full code of youre method and the delegate?
Martin
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Hi,
I get this error in run time, by the way.
Here is the code:
void delegateA(string s)
{
if (this.InvokeRequired)
{
this.Invoke(new DelA(delegateA), new object[] { s });
}
else
{
if (this.itemscounter < this.totalitems)
{
this.itemscounter++;
}
}
}
This is the code where the the delegate listens to:
if (this.DelA != null)
{
this.DelA(this.bufferofserialport);
}
When i change the "< this.totalitems" to "< this.totalitems - 1", its not showing up the error.
But than its not completing till the end of the items in my listbox.
Thanks in advance!
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Hello,
Are you using "itemscounter" for an access of an array somewhere?
for example:
xxx[itemscounter]
or
for(int i=0;i<=itemscounter;i++){ xxx[i]....)
Martin
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Hi,
yes an ArrayList.
I filled the array with items with the for statement.
And using it now like xxx[itemscounter].
And in the if statement i go to the next item in the array.
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Hello,
So it looks like the problem is here.
I guess if you depug the for statement you maybe find out that you whant to access a index which is out of range.
Maybe you just have to change some code from:
for(int x=0;x<=y;x++)
to:
for(int x=0;x<y;x++)
Hope that helps!
All the best,
Martin
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I'm trying to find good example for DataGrid (could be with DataSet example) with local database... I do not want example with SQLserver (which I have seen in many 'net sites), just local database.
Thanks!
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What type of database is your local database?
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I'm looking into simple 2 columns (name of variable, and Interpreted Data)... the interpreted data would be the translation of the raw hex data from a raw data line on file. Since that there are many lines (could be up to 3000 lines in all), wonder if I could set up the dataset to work with datagrid so i can view the data page by page by clicking "next" button?
Hope that clears up.
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I am beginning to understand what your datasource is / looks like. Could you please send me an example of a row of data or two rows of data and I am sure I can assist you.
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Ok.. to clarify what the datasource looks like... (both are string value).
I'm not sure how to set up the dataset so i can look on the next set of data.
from the first row of raw data would have:
Name Interpreted_Value
Color_Used Cyan
Install_Date 12/21/99
Error_Code 848-323
Next row from raw data:
Name Interpreted_Value
Color_Used Magenta
Install_Date 3/21/93
Error_Code 239-772
Next row from raw data:
Name Interpreted_Value
Color_Used Magenta
Install_Date 1/2/03
Error_Code None
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The data in file C:\DataSource.txt from code Looks exactly like below....
Magenta,1/2/03,XDSDF
Blue,1/2/05,None
//I know this is kind of messy but i just slapped it together. let me know if you have any questions.
StreamReader s;
string[] columns = {"Color_Used","Install_Date","Error_Code"};
DataSet ds = new DataSet();
grvMain.DataSource = ds;
ds.Tables.Add("tblMain");
for (int i = 0; i < columns.Length; i++)
{
ds.Tables["tblMain"].Columns.Add(columns[i]);
}
string sFieldDelimiter = ",";
string sRowDelimiter = "\r\n";
s = new StreamReader(@"C:\DataSource.txt");
string sAllData = s.ReadToEnd();
string[] sRowsColSplit = sAllData.Split(sRowDelimiter.ToCharArray());
foreach (string row in sRowsColSplit)
{
if (row != "")
{
string[] rows = row.Split(sFieldDelimiter.ToCharArray());
ds.Tables["tblMain"].Rows.Add(rows);
}
}
grvMain.DataBind();
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I have a collection (IList) of custom objects bound to a DataGridView. When you click on the * line to create a new row the DataGridView automatically creates a new object for you to edit. When it does this it calls the default constructor. What I would like to do is intercept this process so that I can either call a different constructor or else do some extra initialization before the DataGridView tries to bind to it. Is there a way to do this? The RowsAdded and UserAddedRow event both fire too late. Which method is the DataGridView calling to create a new row? I don't think it's actually getting added to the collection until the user edits the row.
Thanks
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One approach is to add a handler for the BindingSource's AddingNew event. E.g.:
InitializeGrid()
{
List<CustomItem> sourceList = new List<CustomItem>();
CustomItem firstItem = new CustomItem("Special content");
sourceList.Add(firstItem);
CustomItem nextItem = new CustomItem();
sourceList.Add(nextItem);
BindingSource bindingSource = new BindingSource();
bindingSource.DataSource = sourceList;
bindingSource.AddingNew += new AddingNewEventHandler(bindingSource_AddingNew);
dataGridView.DataSource = bindingSource;
}
private void bindingSource_AddingNew(object sender, AddingNewEventArgs e)
{
e.NewObject = new CustomItem("Not default content");
}
An alternative is to use the DataGridView's DefaultValuesNeeded event, but the object has already been constructed by the time this event fires.
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I'm not sure if anyone will be able to help me with this problem without actually debugging the code, but I thought I'd give it a shot.
Here's the situation. I have a fairly mature and stable C#/ASP.NET application that I inherited a few years back. I'm familiar with nearly all of the code, but there are few classes here and there that I've never had to deal with; I know they work and that's it.
Late last night we came across a bug in which connections were getting leaked until the pool was saturated with the default 100 connections. It turned out that the connections were getting orphaned in a class that hasn't been touched in about five years. As strange as that is, the part that I really can't explain is that the method is called an several places in the application and it works correctly. However, when it is called in a page that was recently added to the application it leaks connections like a siv.
If it can help, here's the offending method (underscores added for legibility).
<br />
public int GetUserID(String UserName) <br />
{<br />
________
________SqlConnection myConnection = new SqlConnection(ConfigurationSettings.AppSettings["connectionStringUSR"]);<br />
________SqlCommand myCommand = new SqlCommand("GetSingleUserID", myConnection);<br />
<br />
________
________myCommand.CommandType = CommandType.StoredProcedure;<br />
<br />
________
________SqlParameter parameterEmail = new SqlParameter("@Email", SqlDbType.NVarChar, 100);<br />
________parameterEmail.Value = UserName;<br />
________myCommand.Parameters.Add(parameterEmail);<br />
<br />
<br />
________if ((parameterEmail.Value != null) && (parameterEmail.Value != System.DBNull.Value)) <br />
________{<br />
________________
________________myConnection.Open();<br />
<br />
________________SqlDataReader dr = myCommand.ExecuteReader(CommandBehavior.CloseConnection);<br />
________________if(dr.Read()==true)<br />
________________{<br />
________________________if(dr.IsDBNull(0))<br />
________________________________return -1;<br />
________________________else<br />
________________________________return dr.GetInt32(0);<br />
________________}<br />
________________else<br />
________________{<br />
________________________return -1;<br />
________________}<br />
________}<br />
________else<br />
________{<br />
________________return -1;<br />
________}<br />
}<br />
<br />
The myConnection.Close() is missing, but the CommandBehavior is set to CloseConnection so it should be getting closed correctly.
I am at a complete loss why this code would behave different based on what on what's below it on the stack, what in the session, or what's in some static variable, but that seems to be the case.
If anyone can help me figure this out I'll owe you dinner.
Thanks, Jason
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I don't know about you but I don't really trust something to close my connections for me. I'd have the open in a try block and the close in a finally block.
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I couldn't agree more, in fact that's precisely what I did to correct the problem. But I also need to explain why the previous code behaved as it did, both for formal justifications as well as my own curiosity.
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I'd say that a connection that is opened must always be closed, no exceptions. It's plain bad coding to rely on something else to auto close a connection.
As for why the code behaved as it did - I'd just put it down to badly written code.
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Of course the behaviour depends on what else is happening in the code. You are never closing the data reader, so it will be depending on garbage collections to finalize it. If there doesn't happen to be a garbage collection soon, it will be leaking the connection.
Jason Pease wrote: it leaks connections like a siv
Perhaps even like a sieve? 
Jason Pease wrote: nderscores added for legibility
So much work for something that didn't end up very good anyway... Use the pre tag instead.
---
It's amazing to see how much work some people will go through just to avoid a little bit of work.
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Guffa wrote: Of course the behaviour depends on what else is happening in the code. You are never closing the data reader, so it will be depending on garbage collections to finalize it. If there doesn't happen to be a garbage collection soon, it will be leaking the connection.
The garbage collection doesn't seems to be the issue based on the counters in perfmon, but I'm not sure how reliable they are.
Guffa wrote: Perhaps even like a sieve?
No, more like a siv. Very very leaky.
Guffa wrote: So much work for something that didn't end up very good anyway... Use the pre tag instead.
Nice tip. Can you tell I don't post that often?
Thanks, Jason
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Jason Pease wrote: The garbage collection doesn't seems to be the issue based on the counters in perfmon, but I'm not sure how reliable they are.
You are missing the point. Read my reply again, and see if you can spot where I say that you are never closing the data reader.
---
It's amazing to see how much work some people will go through just to avoid a little bit of work.
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Perhaps, you are missing the point.
Try to read my initial post again and see you if you can pick out the phrase where I say the code works, and has worked for years, correctly in many parts of the application. If it were simply a question of never closing the data reader it would have leaked connections from day one.
Or am I missing something here?
---
It's amazing how rude some people are to people that they don't know
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It could depend on a lot of things as to why connections haven't been leaking up until recently. But it still stands that the connection and the data reader both need closing.
I wouldn't bother looking into this too far as you never wrote the code, just fix it and move on.
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Jason Pease wrote: Perhaps, you are missing the point.
Nope. 
Jason Pease wrote: Try to read my initial post again and see you if you can pick out the phrase where I say the code works, and has worked for years, correctly in many parts of the application.
I saw that when I read it the first time. The fact the code does not produce errors is in no way any guarantee that it is correct.
Jason Pease wrote: If it were simply a question of never closing the data reader it would have leaked connections from day one.
It's not simply a question of not closing the data reader. As I explained, it depends on whether there are any garbage collections occuring that will finalize the data reader or not. If the code would have closed the data reader, it would not have to depend on the garbage collector.
The code has been incorrect from day one. You have just been lucky that the garbage collector has been picking up the slack.
---
It's amazing to see how much work some people will go through just to avoid a little bit of work.
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