I have the following column to show a dropdown list to users with options "Yes", "No" or "N/A" and it is bound to a bool? property using a converter class that transforms the literals to true or false and for null values "N/A".
Here is the column definition:
<telerik:GridViewComboBoxColumn x:Name="BoolCol"
Width="165"
UniqueName="BoolCol"
DataMemberBinding="{Binding BoolCol, Mode=TwoWay, Converter={StaticResource BooleanToStringConverter}}"
DisplayMemberPath="Key"
SelectedValueMemberPath="Value"
Header="Bool Col">
</telerik:GridViewComboBoxColumn>
Here is the converter class:
public class BooleanToStringConverter : IValueConverter
{
static public string[] DefaultValues = new string[] { "Yes", "No", "N/A" };
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
var arr = (null != parameter) ? parameter.ToString().Split(',', ';', '|', '/')
: DefaultValues;
if (arr.Length != 3) { arr = DefaultValues; }
if (value is bool)
{
return (bool)value ? arr[0] : arr[1];
}
else
{
return arr[2];
}
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
var arr = (null != parameter) ? parameter.ToString().Split(',', ';', '|', '/')
: DefaultValues;
if (arr.Length != 3) { arr = DefaultValues; }
if (string.Equals((value ?? "").ToString(), arr[2], StringComparison.CurrentCultureIgnoreCase))
{
return null;
}
return string.Equals((value ?? "").ToString(), arr[0], StringComparison.CurrentCultureIgnoreCase);
}
}
The ItemsSource is set on the constructor like this:
var BoolCol = (DataGrid.Columns["BoolCol"] as GridViewComboBoxColumn);
BoolCol.DataType = typeof(System.Nullable<bool>);
BoolCol.ItemsSource = new Dictionary<string, string>() { { "Yes", "Yes"},
{ "No", "No" },
{ "N/A", "N/A"}};
This works fine except that when the user tries to filter by clicking on the column header... the resulting list shows 3 options as expected but instead of showing the values "Yes", "No" or "N/A" it only shows "N/A" an all 3 options.
It is even more puzzling that when you check on any of the options (which all read "N/A") it correctly filters by the right option.... The first one on the array is "Yes" so if you check for the first one it will filter the data for all the true values even if the dropdown on the filter reads "N/A".
Any advices??
Thanks
7 Answers, 1 is accepted
Filtering is a data operation. Extrating the distinct values from the source collection is also a data operation. Data operations are performed over the actual raw data with LINQ queries. IValueConverters and DataStringFormats are UI stuff and they play absolutely no part in the data operations. Presentation and data are two separate things.
You can learn more about what filtering is and how it is performed by those articles:
Basic Filtering
Programmatic Filtering
Column Filtering
If your collection does not contain all distinct values that you want to diplsay you can alter the distinct values by attaching to the DistinctValuesLoading event of the grid which is also described in the documentation.
I hope this helps.
Rossen Hristov
Telerik
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This seems to me like a bug on the Telerik side
You have set your column's DataType to be Nullable<bool>, right? Yet you feed the combo box with strings only:
BoolCol.ItemsSource = new Dictionary<string, string>() { { "Yes", "Yes"},
{ "No", "No" },
{ "N/A", "N/A"}};
There are no bools in your combo box. So how can this combo provide a boolean value for the Binding. It can't. Hence your IValueConverter does nothing and always defaults to the third choice You can debug it to see.
Please respect .NET types -- Nullable<bool> and string are different types. Make sure you have set up your combo correctly by following the documentation.
Regards,
Telerik
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Thanks for your answer... it is a good point that you bring on except that the filtering DOES WORK... it will be nice if you copy and paste the code I posted to see the real issue... the filtering works but the dropdown does not show the proper values... you check any of the options and the filter is applied for the right value.
Being a bit more clear:
Option on the Drop Down Item on the Array Output because of the Converter Filter Applied on the Data
"N/A" "Yes" true All items field value is true
"N/A" "No" false All items field value is false
"N/A" "N/A" null All items field value is null
The issue is that the option on the drop down for the column filter should be like the item on the Array and it does not.
Sorry if I am being a bit stubborn here... really I just want an explanation and solve the issue.. the only thing that I see not working is the dropdown showing wrong values and
I have tried also setting the array with bool?
Thanks
Please, open a new support ticket and attach a runnable dummy sample project which demonstrates the issues that you are having. I will debug it and see what is going on.
Thank you.
Rossen Hristov
Telerik
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Rank 1
In order to understand your scenario better, could you please send us a small isolated project that demonstrates the issue?
Regards,
Boris Penev
Telerik