Trials and Tribulations of DataGridView, Column Selections, and Sorting

PeterRitchie — Tue, 26 Aug 2008 20:06:00 GMT

I had to implement some custom sorting in a DataGridView recently. Essentially, the stakeholders wanted full column selection (like Excel) while still having the ability to sort the data based on a particular column.

This particular DataGridView is data-bound. DataGridView offers the Sort(DataGridViewColumn, ListSortDirection) method to perform this. Nice and easy I thought: I’ll set the SelectionMode to DataGridViewSelectionMode.ColumnHeaderSelect and simply call Sort with the selected column.

Well, much to my chagrin this had the side effect of making that column look selected all the time. No matter where else I clicked, that recently sorted column looked selected (SelectedColumns had a count of zero). And to add insult to injury, when I control-clicked that column (thinking it was selected) to unselected it, it caused a NullReferenceException deep in the framework.

Suffice it to say, this makes it very difficult to sort by columns in DataGridView without using the built-in sort-column-when-header-is-clicked mode.

What I’m now attempting to do is to unselect the column before sorting it. This, in itself, is not trivial either; there’s no public method to select or deselect a column in the DataGridView. I’ve had to create a new DataGridView derivative and call the protected method SetSelectedColumnCore. A few hoops…

I’ve logged a couple of issues on Microsoft Connect about these problems. The first is about ctrl-clicking the column and getting an exception: https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=363623 The second is about the visual state of the column remaining “selected”: https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=363623 Attached to this post you will find the project referenced by the two Connect issues.

[Update: I've currently only tried this with a .NET 2.0 project in Visual Studio 2008 SP1; if you find this problem occurs in Visual 2008 RTM, please comment.]

[Update: I overlooked the DataGridViewColumn.Select property, so there's no need to derive from DataGridView]

Formatting/parsing for a specific culture redux

PeterRitchie — Tue, 22 Jan 2008 23:35:00 GMT

In recent blog post I detailed how creating a culture via the CultureInfo constructor could actually create a user-overridden culture--which could be completely different than the culture that you've requested by name. Fortunately there's a way of overriding the user override (apologies for overloading "override") by supplying the boolean value "false" in a CultureInfo overload.

As Greg Beech commented, there's another method to create a culture--System.Globalization.CultureInfo.CreateSpecificCulture. This sounds like it does exactly what you might expect and creates a "specific" culture. Unfortunately, this method too violates the principle of least astonishment and creates a culture that uses the user-overridden values when the culture name matches that of the user's current culture.

CreateSpecificCulture does not, as far as I can tell, have an overload/alternative to you allow to to force a "specific" culture, so the problem is much worse with CreateSpecificCulture. I've gone ahead and logged a bug for it on Connect: https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=321241

In case you're wondering why this is more serious, consider the following following block of code that formats a date value as text:

System.Globalization.CultureInfo ci;

String text;

ci = System.Globalization.CultureInfo.CreateSpecificCulture("en-us");

text = String.Format(ci, "{0:d}", DateTime.Now);

And that text is transmitted to another application (or another session of the same application, e.g. serialization), potentially in another locale, to be parsed with the following block of code:

System.Globalization.CultureInfo ci;

ci = System.Globalization.CultureInfo.CreateSpecificCulture("en-us");

String text = ReadRecord();

DateTime now = DateTime.Parse(text, ci);

If either (or) the user's current culture is set to "English (United States)" and they've overridden the currency format the short date (say from "M/d/yyyy" to "d/M/yyyy") will randomly result in the wrong date.

Peter Ritchie's MVP Blog : Framework Bugs

Trials and Tribulations of DataGridView, Column Selections, and Sorting

Formatting/parsing for a specific culture redux