I'm auto-generating a grid from a DataTable, and some of the columns need to be converted to more complex layouts than just text. I've successfully applied DataTemplates dynamically where needed, however I cannot run a converter (IValueConverter) because the value it is being given is the DataRow, so I have no way to tell which piece of data I need from the array.
I can't seem to figure out what I'm doing wrong.
Here is relevant code:
<DataTemplate x:Key="DateColumn">
<ContentControl Content="{Binding Converter={StaticResource DateConverter}}" />
</DataTemplate>
public class DateConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return value;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
Any help is greatly appreciated.
I was able to get this working by setting the converter in the code instead of trying to select the template in the xaml. Here is what it looks like now:
column.DataMemberBinding.Converter = new DateConverter();
Note that this is for a Telerik grid. I believe the syntax on a normal data grid is "Binding.Converter" instead of "DataMemberBinding.Converter".
Related
We are normally bind the IValueConverter value like as below,
<Button x:Name="myButton" Content="ClickMe" />
<Image Opacity="{Binding ElementName=myButton, Path=IsEnabled, Converter={StaticResource BoolToOpacityConverter}, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay, ConverterParameter = 1}" />
But my requirement is, without using xaml bind the IValueConverter. Please anyone suggest me how to bind the IValueConverter using c# without using xaml
You would use it in c# exactly the same as if you were using any other class.
So if your value converter is like this:
public class CustomConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
// ... your custom value converter
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
// ... your custom value converter
}
}
you would use it like this:
var customConverter = new CustomConverter();
customConverter.Convert( .. );
I am working on a windows universal app and I'm trying to work out data binding.
I have a listview which has an item template and data template in which a property of a custom class is bound.
<ListView>
<ListView.ItemTemplate>
<DataTemplate>
<Textblock Text="{Binding Name}"/>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
This works fine an displays the names all instances of my custom class in the ObservableCollection I bind to the listview. I was wondering however if there is some way of modifying what is being bound before it is bound without changing the class itself.
I'm trying to bind a capitalisation of the string property Name so if the name was Test I want to bind TEST instead. Currently the way I'm doing this is to have a separate property called NameLabel which I populate like this
NameLabel = Name.ToUpper();
However this seems very messy and I was wondering if there's a neater way of doing it without creating a separate property?
You can use a Converter.
Create a StringToUpper.cs File with a StringToUpper Class which inherits form IValueConverter:
public class StringToUpper: IValueConverter
{
public object Convert(object value, Type targetType,
object parameter, CultureInfo culture)
{
var valueString = value.ToString();
if (!string.IsNullOrEmpty(valueString))
{
return valueString.ToUpper();
}
return string.Empty;
}
public object ConvertBack(object value, Type targetType,
object parameter, CultureInfo culture)
{
// do nothing.
}
}
Add the resource of your created Converter:
...
xmlns:converter="clr-namespace:StringToUpper"
...>
<Window.Resources>
<converter:StringToUpper x:Key="StringToUpperConverter" />
</Window.Resources>
Add the converter:
<Textblock Text="{Binding Name, Converter={StaticResource StringToUpperConverter}}"/>
Here is a good Tutorial about Converters in WPF.
You could create a converter, that turns the value of a property into a form desired for the view (in your case, a simple capitalisation of the string).
Your converter class might look like this:
public class StringToUpperStringConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
var valueString = value.ToString();
if (!string.IsNullOrEmpty(valueString))
{
return valueString.ToUpper();
}
return string.Empty;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
Your xaml might have this defined in the resource section:
<converters:StringToUpperStringConverter x:Key="StringToUpperStringConverter" />
And your binding would then look like this:
<Textblock Text="{Binding Name, Converter={StaticResource StringToUpperStringConverter}}"/>
So I'm trying to build out a project that will allow a user to type some text into a textbox on the left side of the form and that will filter out the available items from my datasource list.
<Label Content="Enter item name below"></Label>
<TextBox Name="SearchTermTextBox" TabIndex="0" Text="" />
I was under the impression I could bind to the datasource the list then use a converter to filter out the items that were unlike the string.
<ListBox DataContext="{Binding Colors}">
<ListBox.ItemsSource>
<MultiBinding Converter="{StaticResource FilterTextValueConverter}" ConverterParameter="{Binding ElementName=SearchTermTextBox, Path=Text}" />
</ListBox.ItemsSource>
<ListBox.ItemTemplate>
//etc...
</ListBox.ItemTemplate>
</ListBox>
However, you can't bind to an elementname in the converterparameter unless you use something called a dependency property.
Edit: Seeing as I've created confusion with the code above, here's the converter I'm trying to bind:
public class FilterTextValueConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
var trackedColors = value as List<Colors>;
if (trackedColors != null)
return (trackedColors).Where(item => item.ColorName.Contains(parameter.ToString())).ToList();
return null;
}
public object ConvertBack(object value, Type targetTypes, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
public class Colors
{
public String ColorName;
public String Description;
}
What is wrong with my approach here? Clearly I'm angering the WPF gods since this is a fairly straightforward operation but I'm being denied it on principle. Any help would be appreciated.
Simple binding with converter will work here, no need for MultiBinding.
<ListBox ItemsSource="{Binding Path=Text, ElementName=SearchTermTextBox,
Converter="{StaticResource FilterTextValueConverter}">
......
</ListBox>
Assuming FilterTextValueConverter is implementing IValueConverter, you can access text from value passed to Convert method.
public class FilterTextValueConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
string text = value.ToString(); // TEXT for textBox can be accessed here.
return new List<string>(); // Return filtered list from here.
}
public object ConvertBack(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
return Binding.DoNothing;
}
}
UPDATE
In case you want to pass multiple bindings to converter, use IMultiValueConverter because ConverterParameter is not Dependency property, hence cannot be bound.
XAML
<ListBox DataContext="{Binding Colors}">
<ListBox.ItemsSource>
<MultiBinding Converter="{StaticResource FilterTextValueConverter}">
<Binding/>
<Binding ElementName="SearchTermTextBox" Path="Text"/>
</MultiBinding>
</ListBox.ItemsSource>
</ListBox>
Converter
public class FilterTextValueConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
var trackedColors = values[0] as List<Colors>;
if (trackedColors != null && !String.IsNullOrEmpty(values[1].ToString()))
return (trackedColors).Where(item =>
item.ColorName.Contains(values[1].ToString())).ToList();
return null;
}
public object[] ConvertBack(object value, Type[] targetTypes,
object parameter,
System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
I continued looking into this issue well after the accepted answer was posted and working for me. What I discovered is that it's a fairly trivial task to wrap the control you're trying to get a new dependencyproperty out of to allow for proper binding.
I will not be accepting my own answer to this determined so much later, but this seems (in my amateur opinion) like a much more elegant solution than adding a converter despite being a bit more complex:
Note that this is for a new dependency on the caretindex property of a textbox, not for the original question on binding, but it just requires some smart renaming to get it working ;).
public class TextBoxDependencyWrapper : TextBox
{
public static readonly DependencyProperty CaretIndexProperty = DependencyProperty.Register(
"CaretIndex", typeof (int), typeof (TextBoxDependencyWrapper), new FrameworkPropertyMetadata(default(int), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, CaretIndexChanged ));
protected override void OnKeyUp(KeyEventArgs e) //Event that changes the property we're trying to track
{
base.OnKeyUp(e);
CaretIndex = base.CaretIndex;
}
protected override void OnKeyDown(KeyEventArgs e) //Event that changes the property we're trying to track
{
base.OnKeyDown(e);
CaretIndex = base.CaretIndex;
}
public new int CaretIndex
{
get { return (int) GetValue(CaretIndexProperty); }
set { SetValue(CaretIndexProperty, value); }
}
}
I need to calculate/change form of input between textbox to its bindable source. The way i trying to achive this, is with help of converters.
Converter:
public class ParameterConverter : IValueConverter
{
public object Convert(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (value == null)
return string.Empty;
string originalParameValue = value.ToString();
string fixedParameterValue = string.Format("#_{0}", originalParameValue);
return fixedParameterValue;
}
public object ConvertBack(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new System.NotImplementedException();
}
}
XAML:
<Window.Resources>
<converters:ParameterConverter x:Key="parameterConverter" />
</Window.Resources>
<Grid>
<TextBox Text="{Binding ParameterA, Converter={StaticResource parameterConverter}}"/>
</Grid>
The problem is, that converter is functioning only once. Is it approach correct (i mean with converter) or there are another approaches ?
Perhaps the binding Mode is not two way, and did your property fire property changed.
Does your data context implement INotifyPropertyChanged and is PropertyChanged being called whenever ParameterA is changed? It seems as if nobody is notifying the textbox that it needs to update its contents.
I'm using a boolean converter in my XAML in a WPF project. I want to disable a few buttons while "IsBusy" is true. I am absolutely sure that IsBusy is being set to true/false properly. I am able to successfully bind directly to IsBusy without the converter. The following does not currently work. I've put breakpoints in the actual converter class and the "Convert" and "ConvertBack" methods are never hit. What is wrong here?
IsEnabled="{Binding IsBusy, Converter={StaticResource InvertedBooleanConverter}}"
Resources:
<Window.Resources>
<converters:InvertedBooleanConverter x:Key="InvertedBooleanConverter" />
</Window.Resources>
Converters:
xmlns:converters="clr-namespace:MyProject.Converters"
The converter:
namespace MyProject.Converters
{
[ValueConversion(typeof(bool), typeof(bool))]
public class InvertedBooleanConverter : IValueConverter
{
#region IValueConverter Members
public object Convert(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
if (targetType != typeof(bool))
throw new InvalidOperationException("The target must be a boolean");
return !(bool)value;
}
public object ConvertBack(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
throw new NotSupportedException();
}
#endregion
}
}
If isBusy dependancy property? if not the change form IsBusy will not be transmitted into isEnable
Take a step back and check that the binding is in the right place -- add <TextBlock Text="{Binding}" /> and make sure it shows the correct class (the one that contains IsBusy).