Totals Row in a DataGridView - winforms

I am developing a winform application application. I wanted to show sum of columns in last row of each column. This row must always be visible.
At moment I am thinking about adding another datagridview just beneath my datagridview with records, and would show the sum in that bottom datagridview.
If there is a better way to achieve this task?

No, need of adding another datagridview
Solution 1: Please refer to this solution
Solution 2: If the above link is not exactly what you want then,
You can try to manually add last, summary, row in which you can display information that you need. For example, you can try to do the following:
Read data from database and fill System.Data.DataTable
Add one column to the newly created DataTable – that column might be set
to true for the last, summary, row
Programmatically add one extra row that contains suitable summary data
Do the data binding to DataGridView control
Using appropriate event, bold or otherwise graphically distinct summary
row (row that have extra column value
set to true)

You can do it in the same way as you suggest, like placing a datagridview for displaying the sum. you can also handle the Horizontal Scroll with this, if there are more columns.
Another method is there in this link
Another way you can Add Rows to your datasource itself to display the sum.

Even if this question is quite old-ish I'd like to propose an extension to Niraj Doshis answer. His answer holds true for a data bound DataGridView. I recently had the problem to calculate the summary in a user-editable DataGridView, whose solution differs in the details. Anyway It's quite straight-forward too. I am writing my functions on a higher abstraction level, which outlines the workflow, but elides the implementation details.
First of all you'll have to initialize the DataGridView, see
private void InitializeDataGridView()
{
SetColumnTypes();
AddEmptyRow();
AddSummaryRow();
}
I set DataGridView.AllowUsersToAddRows to false for the new row would be located beneath the summary row. Hence I am adding an empty row, which the user may fill with his data. The summary row is set to ReadOnly since we do not want our user to edit it. Whenever a CellEndEdit is raised I am updating the DataGridView with the following method
private void UpdateDataGridView()
{
RemoveSummaryRow();
RemoveEmptyRows();
UpdateRowNumbers();
AddEmptyRow();
AddSummaryRow();
}
First I remove the summary and all empty rows (you'll have to take care. If you are trying to delete the row you just edited an exception will be thrown. I've not yet figured out how to do this, but I just made up the solution. I'll amend when I came up with the solution.) Afterwards I'm setting a running number in each of the rows. This is not really required, but a detail of my implementation. At the end I add an empty row again which the user may use to add further data and then calculate and add the summary row.
As I said before this is not yet a ready-made solution, but rather I concept which works but with some quirks and bugs.

Related

WPF Data gird row selection change event from selection change event

I'm looking for a workaround to an issue I've noticed in a project that I'm working on. I have a datagrid bound to a list of a class I've created. Whenever a user types in a stock symbol in this datagrid I have the roweditending event set to pull in some information to populate the other fields in the datagrid.
This generally works fine, however I've noticed that the event doesn't fire in some instances. I'm going to try to explain this the best I can... upon data entry if I enter information into a cell and then click another row on the datagrid - focus doesn't shift to the new row but shifts to the row containing the cell I was just entering data into from that cell, then if I select another row or input element the row edit ending event doesn't appear to fire and as such my code to populate the rest of the row doesn't execute.
Everything else is fine, and it's a pretty subtle issue, only one path of input to make it happen, but I was wondering if anyone had run into this or found a work-around?
I've been looking at the selection change event, but I need to be able to grab the row that was selected. In the row edit ending event I use
Dim NewTrade As Trade = e.Row.DataContext
to get the instance of my class that the row represents and to add the additional fields.
I'm not sure I see a way to get the row and it's datacontext for the row I just shifted from using the SelectionChangedEventArgs.
Any ideas for a workaround?

How to quickly populate a combobox with database data (VCL)

I have read all sorts of documents across the web about what should be a farly common and painless implementation. Since I have found no consistent and slick reply (even the Embarcadero website describes some properties wrong!) I am going to post a "short" howto.
Typical, frequent use case: the developer just wants to painlessy show a couple of database-extracted information in a combo box (i.e. a language selection), get the user's choice out of it and that's it.
Requirements:
Delphi, more or less any version. VCL is covered.
A database table. Let's assume a simple table with an id and value fields.
A DataSet (including queries and ClientDataSets).
A DataSource linked to the DataSet.
A TDBLookupComboBox linked to the DataSource that shall show a list of values and "return" the currently selected id.
Firstly, we decide whether the sort order is the one we want or not and if all the items in that table must be shown. Most often, a simple ORDER BY clause or a DataSet index will be enough. In case it's not, we may add a sort_order field and fill it with integers representing our custom sort order. In case we want to show just some items, we add a visible or enabled field and use it in our SQL. Example:
SELECT id, value
FROM my_database_table
WHERE visible = 1
ORDER BY sort_order
I have defined visible as INTEGER and checking it against 1 and not TRUE because many databases (including the most used SQLite) have little support for booleans.
Then an optional but surprisingly often nice idea: temporarily add a TDBGrid on the form, link it to the same TDataSource of the TLookupComboBox and check that you actually see the wanted data populate it. In fact it's easy to typo something in a query (assuming you are using a SQL DataSet) and get no data and then you are left wondering why the TDBLookupComboBox won't fill in.
Once seen the data correctly show up, remove the grid.
Another sensible idea is to use ClientDataSets for these kinds of implementations: due to how they work, they will "cache" the few rows contained in your look ups at program startup and then no further database access (and slowdown and traffic) will be required.
Now open the TDBLookupComboBox properties and fill in only the following ones:
ListSource (and not DataSource): set it to the TDataSource connected to the DataSet you want to show values of.
ListField: set it to the field name that you want the user to see. In our demo's case it'd be the value field.
KeyField: set it to the field name whose value you want the program to return you. In our demo it'd be the id field.
Don't forget to check the TabOrder property, there are still people who love navigating through the controls by pressing the TAB key and nothing is more annoying than seeing the selection hopping around randomly as your ComboBox was placed last on the form despite graphically showing second!
If all you need is to show a form and read the TDBLookupComboBox selected value when the user presses a button, you are pretty much sorted.
All you'll have to do in the button's OnClick event handler will be to read the combo box value with this code:
SelectedId := MyCombo.KeyValue;
Where SelectedId is any variable where to store the returned value and MyCombo of course is the name of your TDBLookupComboBox. Notice how KeyValue will not contain the text the user sees onscreen but the value of the id field we specified in KeyField. So, if our user selected database row was:
id= 5
value= 'MyText'
MyCombo.KeyValue shall contain 5.
But what if you need to dynamically update stuff on the form, depending un the combo box user selection? There's no OnChange event available for our TDBLookupComboBox! Therefore, if you need to dynamically update stuff around basing on the combo box choices, you apparently cannot. You may try the various "OnExit" etc. events but all of them have serious drawbacks or side effects.
One possible solution is to create a new component inheriting from TDBLookupComboBox whose only task is to make public the hidden OnChange event. But that's overkill, isn't it?
There's another way: go to the DataSet your TDBLookupComboBox is tied to (through a DataSource). Open its events and double click on its OnAfterScroll event.
In there you may simulate an OnChange event pretty well.
For the sake of demonstration, add one integer variable and a TEdit box to the form and call them: SelectedId and EditValue.
procedure TMyForm.MyDataSetAfterScroll(DataSet: TDataSet);
var
SelectedId : integer;
begin
SelectedId := MyDataSet.FieldByName('id').AsInteger;
EditValue.Text := MyDataSet.FieldByName('value').AsString;
end;
That's it: you may replace those two demo lines with your own procedure calls and whatever else you might need to dynamically update your form basing on the user's choices in your combo box.
A little warning: using the DataSet OnAfterScroll has one drawback as well: the event is called more often than you'd think. In example, it may be called when the dataset is opened but also be called more than once during records navigation. Therefore your code must deal with being called more frequently than needed.
At this point you might rub your hands and think your job is done!
Not at all! Just create a short demo application implementing all the above and you'll notice it lacks of an important finishing touch: when it starts, the combo box has an annoying "blank" default choice. That is, even if your database holds say 4 choices, the form with show an empty combo box selected value at first.
How to make one of your choices automatically appear "pre-selected" in the combo box as you and your users expect to?
Simple!
Just assign a value to the KeyValue property we already described above.
That is, on the OnFormCreate or other suitable event, just hard-code a choice like in example:
MyCombo.KeyValue := DefaultId;
For example, by using the sample database row posted above, you'd write:
MyCombo.KeyValue := 5;
and the combo box will display: "MyText" as pre-selected option when the user opens its form.
Of course you may prefer more elegant and involved ways to set a default key than hard-coding its default value. In example you might want to show the first alphabetically ordered textual description contained in your database table or whatever other criterium. But the basic mechanic is the one shown above: obtain the key / id value in any manner you want and then assign it to the KeyValue property.
Thank your for reading this HowTo till the end!

Creating an Empty DataGrid

I was wondering what the best way was to create an empty datagrid.
For example after you have hit new in excel, You have a grid with empty rows and columns.
I am using c# with WPF and .net 4.0.
Thank you.
As the comments have suggested, a datagrid is not a spreadsheet, but a method to display / edit existing data. That said if you want something similar, feel free to populate a collection with default / 'empty' objects and bind that to your grid. It just means that after working with the data, you will have to define a method to capture only the edited rows. This still means that the column-bound properties of your class need to be known ahead of time.
A DataGrid is used to display a collection. If you want to create an individual row DataGrid is not really the right tool. You could but a single empty row in the DataGrid using a collection of only on row. There is a lot of guidance on Master Detail on MSDN. If you don't know how many columns at design time you could used a DataGrid to turn the row vertical with column 1 as name and column as value so now you have one record but with a collection of fields.

How to prevent repeating values in Telerik RadGridView column

I have a radgridview with three columns: Company, Name, Status.
I want to try to prevent repeating instances of the company name when sorted by that column to avoid it showing the same company name over and over and over. Each row is bound to a single viewmodel where it gets its cell data from.
Is there anything I could use to accomplish this, so that a cell can check the cell in the same column in the row above it and if it's the same value, hide its own value so as to not repeat the same company name?
A suggestion would be to listen out for one of the Sorting or Sorted events and then you should be able to hide the data in some way. If nothing else I'd assume that you could use CellStyleSelector change the style of cells to have white text on a white background or something similar.
However, it might be worth asking Telerik themselves since I think they offer free help with these kinds of questions and they might have a better answer.

WPF DataGrid row validation error count

I'm currently facing the problem, that I import an Excel file to a DataGrid.
This works pretty fine, but after importing the table, I need to know how many rows are invalid.
I have applied several validation rules for the different datatypes, and I have an icon in the row header, that shows up if the row is invalid.
But since I have more that 10.000 rows in the grid, I don't want scroll all the way through it to find the errors.
Any ideas, how to determine the count of invalid rows (and then maybe bind that to a textbox)?
Thx
Well, if you're using WPF in the manner that I would term to be "correctly", you shouldn't care about the DataGrid itself in order to get the results you want. You could just run a simple LINQ expression off of the data that the grid is bound to coming up with the count of invalid rows.
That is indeed the solution to one part of the problem. But the user can also edit the values, so they are validated before they are written back to the datatable...
Your approach would cover the import (null values etc.). I think that I have to write an own class, that iterates through the rows and their rowerrors...

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