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Datagrid calculated column not updatingI have a datagrid (C# Windows Forms App) bound to a dataset. One column
in the dataset is a calculated column based on an expression that simply subtracts the value in one column from the value in another column. I created the dataset using a dataset control and the properties dialog boxes. The dataset is not populated from a database - the data is entered into the grid by the user. By adding the following line of code in the form load event handler: dtChequeNos.Columns["line_count"].Expression = "to_seq_no - from_seq_no"; I was able to get the column to perform the calculation but it only displays the result when the user moves to a new row in the grid. I need the calculated column to display the result before the user moves to a new row. Is this possible? David,
It is not a nice solution, however we have the method for this on our website (which is a VB Net website so no C# however it should be clear the difference is almost less than nothing) http://www.vb-tips.com/default.aspx?ID=30d9d2fd-9f10-4928-b7c8-1def3152436f I hope this helps, Cor On 28 Jan 2006 14:34:15 -0800, "David Kirkman"
<foxwaycomput***@gmail.com> wrote: Show quote >I have a datagrid (C# Windows Forms App) bound to a dataset. One column Yes, but you will need to make the column that displays the calculated>in the dataset is a calculated column based on an expression that >simply subtracts the value in one column from the value in another >column. I created the dataset using a dataset control and the >properties dialog boxes. The dataset is not populated from a database - >the data is entered into the grid by the user. >By adding the following line of code in the form load event handler: > >dtChequeNos.Columns["line_count"].Expression = "to_seq_no - >from_seq_no"; > >I was able to get the column to perform the calculation but it only >displays the result when the user moves to a new row in the grid. I >need the calculated column to display the result before the user moves >to a new row. Is this possible? value a "nonCalculated column, otherwise (I think) the calculation will be done twice if you use the example: Use the ColumnChanged event to calculate the value. Here is an example of the ColumnChanged event from the VS 2005 help files (VS 2003 will be the same). You may have to refresh the row to make the new value display in the column you calculated. private static void Column_Changed(object sender, DataColumnChangeEventArgs e ) { Console.WriteLine("Column_Changed Event: name={0}; Column={1}; original name={2}", e.Row["name"], e.Column.ColumnName, e.Row["name", DataRowVersion.Original]); } HTH Otis Mukinfus http://www.otismukinfus.com http://www.tomchilders.com David, in addition to Otis,
Be aware that AFAIK it seems that the column changed event is working in all versions different. (In my idea does in the version 2003 nothing when it is in the same row in the datagrid, because the datagrid is telling nothing then to the underlaying datasource, that hapens at a datarowchange) However I can be wrong, it is just AFAIK (as far as I know). Cor Show quote "Otis Mukinfus" <ph***@emailaddress.com> schreef in bericht news:lj5qt1tttn61sp5eegs10d7oentbp61kd4@4ax.com... > On 28 Jan 2006 14:34:15 -0800, "David Kirkman" > <foxwaycomput***@gmail.com> wrote: > >>I have a datagrid (C# Windows Forms App) bound to a dataset. One column >>in the dataset is a calculated column based on an expression that >>simply subtracts the value in one column from the value in another >>column. I created the dataset using a dataset control and the >>properties dialog boxes. The dataset is not populated from a database - >>the data is entered into the grid by the user. >>By adding the following line of code in the form load event handler: >> >>dtChequeNos.Columns["line_count"].Expression = "to_seq_no - >>from_seq_no"; >> >>I was able to get the column to perform the calculation but it only >>displays the result when the user moves to a new row in the grid. I >>need the calculated column to display the result before the user moves >>to a new row. Is this possible? > Yes, but you will need to make the column that displays the calculated > value a "nonCalculated column, otherwise (I think) the calculation > will be done twice if you use the example: > > Use the ColumnChanged event to calculate the value. Here is an > example of the ColumnChanged event from the VS 2005 help files (VS > 2003 will be the same). > > You may have to refresh the row to make the new value display in the > column you calculated. > > private static void Column_Changed(object sender, > DataColumnChangeEventArgs e ) > { > Console.WriteLine("Column_Changed Event: name={0}; Column={1}; > original name={2}", > e.Row["name"], e.Column.ColumnName, e.Row["name", > DataRowVersion.Original]); > } > > HTH > > Otis Mukinfus > http://www.otismukinfus.com > http://www.tomchilders.com On Sun, 29 Jan 2006 21:36:13 +0100, "Cor Ligthert [MVP]"
<notmyfirstn***@planet.nl> wrote: >David, in addition to Otis, Thanks, Cor. I was not aware the two versions had different behavior.> >Be aware that AFAIK it seems that the column changed event is working in all >versions different. > >(In my idea does in the version 2003 nothing when it is in the same row in >the datagrid, because the datagrid is telling nothing then to the >underlaying datasource, that hapens at a datarowchange) > >However I can be wrong, it is just AFAIK (as far as I know). > >Cor [snip] Otis Mukinfus http://www.otismukinfus.com http://www.tomchilders.com David:
The problem is that the Expression isn't calclated until after the edit is complete. So when you're making the change in the row in the grid, it's still in Edit mode. by calling EndEdit on the row, or EndCurrentEdit on the bindingManager/context that the grid's bound to, the refresh will take place. To facilitate this, you can check for the ColumnChanging or the CurrentCellChanging. Depending on how many expressions you have in the table, you may want to trap different events. In this example, I trap CurrentCellChange and just end the edit, which causes the Expression to recompute. You could add functionality to check for your specific column or depending on the column, take a different course of action. The main thing to understand though is why it's not updating and that's b/c the row is still in Edit mode (which for example, as far as its concerned, means you could undo the changes you just made) so it won't change until you've finished the edit. Here's code that will do it for you: private void dataGridView1_CurrentCellChanged(object sender, EventArgs e) { if (dataGridView1.CurrentRow != null && dataGridView1.CurrentRow.Index >= 0) { dt.Rows[dataGridView1.CurrentRow.Index].EndEdit(); } } Show quote "David Kirkman" <foxwaycomput***@gmail.com> wrote in message news:1138487655.189128.250720@g44g2000cwa.googlegroups.com... >I have a datagrid (C# Windows Forms App) bound to a dataset. One column > in the dataset is a calculated column based on an expression that > simply subtracts the value in one column from the value in another > column. I created the dataset using a dataset control and the > properties dialog boxes. The dataset is not populated from a database - > the data is entered into the grid by the user. > By adding the following line of code in the form load event handler: > > dtChequeNos.Columns["line_count"].Expression = "to_seq_no - > from_seq_no"; > > I was able to get the column to perform the calculation but it only > displays the result when the user moves to a new row in the grid. I > need the calculated column to display the result before the user moves > to a new row. Is this possible? > Thanks for the help guys.
I forgot to mention that I am using 2003. In the end I removed the expression from the column and set the value in the CurrentCellChanged event handler: protected void dataGrid1_CurrentCellChanged(object sender, EventArgs e) { int rowNum = dataGrid1.CurrentCell.RowNumber; int colNum = dataGrid1.CurrentCell.ColumnNumber; if (colNum == 2 || colNum == 5) { dataGrid1[rowNum, 6] = (int)dataGrid1[rowNum, 4] - (int)dataGrid1[rowNum, 1]; } } David  |
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