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i had a question i've been wondering about... when using winforms, you have to access controls on the same thread that owns that control, so from another thread you have to create a new delegate and call it via Invoke(), which marshals the call to the owning thread and works fine. my concern is the creation of the new delegate every time you call Invoke(). if I am calling Invoke very often, then the new delegate you have to create and pass to it would be rather inefficient, right? because when i do call Invoke, in my case i do know which function i want to be called at compile time, and it seems more efficient to create the delegate once, and pass that same object to Invoke everytime it's called. however, when trying to create a delegate like so:
public void delegate handler();
handler delegate_handler = new handler(myFunc);
i get some compile time error about not being able to reference non-static stuff.
any comments or suggestions?
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You don't need to create the delegate each time. If you're invoking the same method over and over again, create the delegate once and keep a reference to it. It's merely a managed method pointer.
You can create a delegate that references both static and instance methods, but you have to include either the class name or the object reference with the method, just as if you were going to call the method without using a delegate (and the same rules for methods defined on the executing class are the same as well).
So, lets say you want to set the text for a TextBox from another thread and you expect to do it quite a bit. Do something like this:
private delegate void SetValueDelegate(object obj, object value,
object[] index);
private SetValueDelegate _setValueDelegate;
public void SafeSetText(TextBox tb, string value)
{
if (tb == null) throw new ArgumentNullException("tb");
if (tb.InvokeRequired)
{
if (_setValueDelegate== null)
{
PropertyInfo pi = tb.GetType().GetProperty("Text");
_setValueDelegate= new SetValueDelegate(pi.SetValue);
}
tb.Invoke(_setValueDelegate, new object[] {tb, value, null});
}
else tb.Text = value;
}This is just a sample, of course, but notice how I create a delegate that references an instance method using pi.SetValue. Even though the delegate isn't referencing a method on the control (that's much easier; with getting/setting properties you have to use reflection or the component model), the delegate is still invoked in the control's thread in which it was created.
Microsoft MVP, Visual C#
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I'm hammering a richtextbox with huge amounts of text at a very fast pace
and using a wide variety of color-coding and multiple font styles. It works
reasonably well for the most part, but every so often the following two
things happen:
1) sometimes things don't get color-coded
2) exception is thrown
A coworker of mine tried the same thing, and reported the same type of
instability with the richtextbox... Is there something I can use that is
stable when using mass amounts of text with tons of varied colors and fonts?
Or is there a way to fix this instability in the richtextbox?
Thanks.
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What do you need the RichTextbox for?
I know of a few other editors that have support for varied colors, but I don't know any that allow multiple fonts.
Aaron Eldreth
TheCollective4.com
My Articles
While much is too strange to be believed,
Nothing is too strange to have happened.
- T. Hardy
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which tool do you suggest i use then? i want to be able to do a ton of color coding and changing of fonts and styles.
it seems of all the tools provided, richtextbox seems the most versatile. i don't think i can do the same things with a listview.
i am writing a test tool that outputs a ton of text for logging. it would be nice for things to be color coded and styled according to severity.
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I'm really sorry, I don't know of any editors that can do what you want. So, you could either try to create your own edit control for your neads, or abandon the richtextbox and go for the textbox.
Aaron Eldreth
TheCollective4.com
My Articles
While much is too strange to be believed,
Nothing is too strange to have happened.
- T. Hardy
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Hi,
I try to update Sql server DB with update from dataset but fails on the DataAdapter.Update with insert exception. here's my code :
<br />
<br />
try<br />
{<br />
<br />
sSQLSel = @"SELECT * From MidnightReadings";<br />
sSQLUpd = @"UPDATE MidnightReadings SET MR_Date = @MR_Date, Coal_Feeder_Tot = @Coal_Feeder_To" +<br />
"t, Coal_Silo_Level_Prct = @Coal_Silo_Level_Prct, Coal_Barn_Inv_Prct = @Coal_Barn" +<br />
"_Inv_Prct, Limestone_Feed_Total = @Limestone_Feed_Total, LS_Silo_Level_Prct = @L" +<br />
"S_Silo_Level_Prct, Ammonia_Totalizer = @Ammonia_Totalizer, Prop_to_Burn_Totalize" +<br />
"r = @Prop_to_Burn_Totalizer, TwentyFourHr_SO2_Reduct = @TwentyFourHr_SO2_Reduct," +<br />
" Limestone_Received = @Limestone_Received, Ammonia_Received = @Ammonia_Received," +<br />
" Prop_Received = @Prop_Received, Est_hours_Dry_Oper_Hours = @Est_hours_Dry_Oper_" +<br />
"Hours, Est_hours_Dry_Oper_Mins = @Est_hours_Dry_Oper_Mins, LAB_Sulfur_Content_Pr" +<br />
"ct = @LAB_Sulfur_Content_Prct, LAB_High_Heat_Val = @LAB_High_Heat_Val, CEMS_SO2_" +<br />
"Daily_Avg = @CEMS_SO2_Daily_Avg, SO2_Daily = @SO2_Daily, Raw_Water_Pump_Meter = " +<br />
"@Raw_Water_Pump_Meter, Reservoir_Level = @Reservoir_Level, Comments = @Comments," +<br />
" Date_Rec_Added = @Date_Rec_Added WHERE (MR_Date = @MR_Date)";<br />
<br />
<br />
SqlConnection myCon = new SqlConnection(sCon1);<br />
<br />
SqlDataAdapter da = new SqlDataAdapter(sSQLSel, myCon);<br />
<br />
da.UpdateCommand = new SqlCommand(sSQLUpd, myCon);<br />
<br />
<br />
buildMNUpdParams(da.UpdateCommand);<br />
da.Update(dsDiff,"MidnightReadings"); <- Fails here !<br />
dsDiff.AcceptChanges();<br />
myCon.Close();<br />
<br />
return true;<br />
<br />
public static void buildMNUpdParams(SqlCommand workCommand)<br />
{<br />
<br />
<br />
SqlParameter workParam = null;<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@MR_Date", SqlDbType.DateTime, 8));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "MR_Date";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Coal_Feeder_Tot", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Coal_Feeder_Tot";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Coal_Silo_Level_Prct", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Coal_Silo_Level_Prct";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Coal_Barn_Inv_Prct", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Coal_Barn_Inv_Prct";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Limestone_Feed_Total", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Limestone_Feed_Total";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@LS_Silo_Level_Prct", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "LS_Silo_Level_Prct";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Ammonia_Totalizer", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Ammonia_Totalizer";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Prop_to_Burn_Totalizer", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Prop_to_Burn_Totalizer";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@TwentyFourHr_SO2_Reduct", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "TwentyFourHr_SO2_Reduct";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Limestone_Received", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Limestone_Received";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Ammonia_Received", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Ammonia_Received";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Prop_Received", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Prop_Received";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Est_hours_Dry_Oper_Hours", SqlDbType.Int, 4));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Est_hours_Dry_Oper_Hours";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Est_hours_Dry_Oper_Mins", SqlDbType.Int, 4));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Est_hours_Dry_Oper_Mins";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@LAB_Sulfur_Content_Prct", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "LAB_Sulfur_Content_Prct";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@LAB_High_Heat_Val", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "LAB_High_Heat_Val";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@CEMS_SO2_Daily_Avg", SqlDbType.Int, 4));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "CEMS_SO2_Daily_Avg";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@SO2_Daily", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "SO2_Daily";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Raw_Water_Pump_Meter", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Raw_Water_Pump_Meter";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Reservoir_Level", SqlDbType.Decimal, 9));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Reservoir_Level";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Comments", SqlDbType.VarChar, 200));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Comments";<br />
workParam = workCommand.Parameters.Add(new SqlParameter("@Date_Rec_Added", SqlDbType.DateTime, 8));<br />
workParam.Direction = ParameterDirection.Input;<br />
workParam.SourceColumn = "Date_Rec_Added";<br />
workParam = workCommand.Parameters.Add(new System.Data.SqlClient.SqlParameter("@MR_ID", System.Data.SqlDbType.BigInt, 8, System.Data.ParameterDirection.Input, false, ((System.Byte)(0)), ((System.Byte)(0)), "MR_ID", System.Data.DataRowVersion.Original, null));<br />
}<br />
<br />
Any ideas ?
Thanks,
JJ
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Could you post the exception? That's a lot of code to look through with out any sort of clue as to where to start looking.
"You can have everything in life you want if you will just help enough other people get what they want." --Zig Ziglar
The Second EuroCPian Event will be in Brussels on the 4th of September
Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!
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I am getting an InvalidOperationException with a message of "Insert". That's it, pretty useless message. Only hints that it didn't like my Statement for update command I guess. I am using a diffgram dataset to update database.
JJ
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If your DiffGram includes inserts, updates, and deletes, all the related properties on a DataAdapter must be assigned. So, if a row was updated and all you supplied was the InsertCommand, then you would see such an operation because the DataAdapter doesn't know how to update the data store.
Microsoft MVP, Visual C#
My Articles
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HI Heath,
That's what I thought too. So in the method that I use to update db. I assigned the Insert command to DataAdapter along with the Update command to DataAdapter. Now it runs but when I execute the DataAdapter update method. I get a new row in database instead of actually updating same row. When I update the datarow with values how do I tell the diffram dataset to go to update mode as well?
Here I find the datarow I want to update in dataset:
<br />
nRow2 = dsDiff.Tables["MidnightReadings"].Select(sRecFind);<br />
It finds it in dataset with no problem
Then I update datarow:
<br />
nRow2[0]["Coal_Feeder_Tot"] = tbCoalFeederTot.Text;<br />
nRow2[0]["Coal_Silo_Level_Prct"] = tbCoalSiloPrct.Text;<br />
nRow2[0]["Coal_Barn_Inv_Prct"] = tbCoalBarnInvPrct.Text;<br />
nRow2[0]["Limestone_Feed_Total"] = tbLimeFeedTot.Text;<br />
I checked the dataset and changes are there but here is the status of row:
<br />
<MidnightReadings diffgr:id="MidnightReadings2" msdata:rowOrder="1" diffgr:hasChanges="inserted"><br />
<MR_Date>2004-06-10T00:00:00.0000000-04:00</MR_Date><br />
<Coal_Feeder_Tot>8789</Coal_Feeder_Tot><br />
<Coal_Silo_Level_Prct>95.5</Coal_Silo_Level_Prct><br />
<Coal_Barn_Inv_Prct>75.8</Coal_Barn_Inv_Prct><br />
<Limestone_Feed_Total>0</Limestone_Feed_Total><br />
<LS_Silo_Level_Prct>0</LS_Silo_Level_Prct><br />
...<br />
This dataset already exists in db but keeps inserting new records.
What am I missing?
Thanks,
JJ
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Make sure the row information contains a primary key so that the UpdateCommand can effectively use a WHERE clause so that the right row is updated.
Microsoft MVP, Visual C#
My Articles
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Hi Heath,
Ok really frustrated with trying to create a diffgram dataset.
I assume that I should first create a DataAdapter then build SqlCommand,InsertCommand, UpdateCommand for Adapter, Correct?
Next build parameters for each Commmand, Correct? After that I can then
Fill dataadapter, correct? Then I write my diffgram out to a file.
Does this sound like the correct approach to this?
After I do this I then take dataset and do inserts, updates etc. to
dataset. After done with this process I go back create a new dataadapter with whats mentioned above and call DataAdapter.Update.
What do you think? I did away with the webservice and have the create diffgram and database updates in a separate class.
Thanks,
JJ
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To call Fill, you only need the SelectCommand set. When you call DataAdapter.Update, however, you may need all four set depending on what changes have been made. After calling Update, though, there will be no changes because the DataAdapter then calls AcceptChanges on your DataSet or DataTable (whichever you passed in).
So, you really only need to write out a DiffGram (if that's really necessary) after you make changes, otherwise those won't be any differences.
Microsoft MVP, Visual C#
My Articles
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See I need the diffgram because this is a pda app that is only sometimes connected to DB. So I need a way to record data to pda then update the database when a connection can be made. So I thought the diffgram would be the easiest way to accomplish this.
JJ
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I was wondering if it was possible to import a comma delimited text file into a access database using c#? If someone could help me out that would be great.
Thanks.
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Of course it's possible. Create an OleDbConnection to an MDB database file, then create an OleDbCommand from that with something like INSERT INTO MyTable VALUES(?, ?, ?, ...) for the CommandText. Then create an OleDbParameter for each ?.
Open the comma-delimited text file and split the strings on , (if you have other commas in the text, you'll need to do a little better job parsing taking quotes into account). For each line you read in and split, set the values of the OleDbParameters you created above and call OleDbCommand.ExecuteNonQuery (after opening your connection for the batch, of course). When you're done, close the connection.
Read about the OleDbConnection, OleDbCommand, and OleDbParameter in the .NET Framework SDK. If you have specific question, please don't hesitate to ask.
Microsoft MVP, Visual C#
My Articles
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How can I get the text in a DataGridTextBoxColumn to word wrap by default? The text just extends off the end of my DataGrid on a single line, even if I set the word wrap property of the Column's TextBox to true. If I select a TextBox for editing, then it wraps, but only while selected.
E. Simmons
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The TextBox is only displayed when editing. When the text is displayed, it is simply drawn in the bounds and is clipped.
In order to word-wrap when displaying the text, you must extend DataGridTextBoxColumn and override Paint (the one with the most parameters, sine that's the one that's ultimately called) and GetMinimumHeight. When painting the string, make sure that StringFormatFlags.NoWrap is not set (negating the StringFormat.FormatFlags property with a bitwise AND), and set/unset anything else you want/don't want, including for other properties of the StringFormat.
The trick is that you have to use the Graphics object passed to Paint to call MeasureString, so that you can adjust the return value of GetMinimumHeight (since only enough for one line of text is displayed by default), but nothing that can't be done.
Microsoft MVP, Visual C#
My Articles
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Ahhhh, that works nicely. Thank you.
E. Simmons
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The function in unmanaged DLL get char* as parametar. When I try to use that function with (out) string parametar, program breaks. How to use that function?
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A char* is a string - they're both already pointers. So, don't use out or ref with a string unless you see an unmanaged declaration like char** or LPCSTR* or something.
BTW, if the string is actually a TCHAR*, TCHAR[], or LP(C)TSTR, then make sure you specify CharSet.Auto. If the declaration is a char* or LP(C)STR, be sure to specify CharSet.Ansi since strings are Unicode in .NET natively. Both the DllImportAttribute and StructLayoutAttribute define a CharSet field you should set in the attribute in such a case.
Microsoft MVP, Visual C#
My Articles
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If I pass only string as parametar program breaks with error message: "Object reference is not set to an instance of an object". Pass parremetar is char* type in dll.
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And is the string set to something? Trust me, a char* is a string - in any language.
If the string is supposed to be an output parameter, do not use the out keyword but instead use the OutAttribute. This tells the marshaler that the parameter is an output parameter and will be assigned when the function returns.
Microsoft MVP, Visual C#
My Articles
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If I understand you well, this is a solution for problem:
[DllImport("Kernel32.dll", CharSet=CharSet.Ansi)]
public static extern bool GetComputerName([Out,MarshalAs(UnmanagedType.LPTStr)] string f1, out int a2);
.
.
.
int v = 0;
string a = "";
if (GetComputerName(a, out v))
{
MessageBox.Show(a+" " + v);
}
But, this will not work???
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