Changes

A collection of property-based content filtering criteria can be applied to child object lists. {{Version/WinXSince|2.6.1}} Some common use cases are as follows.* A user The UI can enter a text be customized to accept user inputs as filter criteria, and reduce the entire child list to a sub -list of those whose certain based on property display values that contain that text;* A customizer . Each filter is 'attached' to a single metaproperty, and multiple filters can create UI that presents several text input fields serving as such filters, with each be applied to a different propertyat once.

For exampleperformance/usability reasons, the result list is not immediately refreshed as one types in the text box. One can customize Instead, it only happens after the ChildArea ReloadChildListCommand is triggered. However, note that these content-based filters:* Require a custom [[SYSCLS_CHILDAREATEMPLATE|Child Area template name]] to work. This customizing will not work applied to include the followingUBIKChildArea.* Work directly on the Children.Items collection. While filters are active, anything derived from this collection (such as Children.Items.Count or custom datasources like [[XAML_Changes_in_UBIK_WinX_3.5#Filtering_by_expressions|ListCollectionView]] / [[Xamarin_XAML#Content_filtering|sfDataSourceExt]]) will also be affected.<br><br> == Usage ==For simple text input, it is enough to create a text input control with a TwoWay relationship to the Children.Filter[x]. However, the TwoWay binding doesn't always work well with more advanced implementations, such as selection. In such cases, the alternative is to use the UpdatePropertyFiltersCommand to supply the filter criteria. Both approaches are described below. === Text Input ===<tabs> <tab name="UWP">

<Grid>TextBox <Border Background="#8000488E" Visibility="{Binding Children.Filters[SomePropertyName], Converter={StaticResource NullObjOrEmptyStrColConverter}}" /> <Border Background="#90707070" Visibility="{Binding Children.Filters[SomePropertyName], Converter={StaticResource NullObjOrEmptyStrVisConverter}}" /> <TextBox Text="{Binding Children.Filters[SomePropertyName], Mode=TwoWay, Converter={StaticResource FilterCriterionToValueConverter}}" PlaceholderText="SomePropertyName" BorderThickness="0" Foreground="White" Background="Transparent" /> </Grid>

When multiple filters are used at === Selection ===Selection is trickier to achieve than direct input, as often a metaproperty's actual value might differ from the same timetext that is displayed for that value. Just think of integer-based statuses, they are combined with "logic and"or GUID properties.

For performance==== List Properties ====The below examples use a custom ComboBox/usability reasons, the result Picker control to display a list of items. Because the filter comparison is not immediately refreshed as one types in based on the text box. InsteadDisplayValue of the metaproperty, it only happens after the [[ReloadChildListCommand]] DisplayText of the selected object is triggeredthen passed on as a part of the command parameter and later used as a filter criterion to filter for objects that have the same the string.

{{Hint|The Borders in the example are not mandatory<tabs> <tab name="UWP"><source lang = "xml">xmlns:controls="using:UBIK. They serve as indicators of whether a filter is currently applied on the result listWinX. The PlaceHolderText is optional as wellControls"xmlns:core="using:Microsoft.}}Xaml.Interactions.Core"xmlns:interactivity="using:Microsoft.Xaml.Interactivity"

<controls:ComboBoxExt x:Name="ComboBox" PlaceholderText="{Binding Children.Filters[STATUSCOLOR].Value, TargetNullValue='SELECT', FallbackValue='SELECT'}" DisplayMemberPath="DisplayText" SelectedValuePath="DisplayText" SelectedValue= UpdatePropertyFiltersCommand "{Binding Children.Filters[STATUSCOLOR].Value}" SelectedValueExt="{Version/XamarinSince|1Binding Children.2}Filters[STATUSCOLOR].Value} " ItemsSource="{Binding Children.Items[0].Properties.AllItems[STATUSCOLOR].MetaProperty.SelectiveList, Converter=={StaticResource SelectiveListToItemsConverter}}">

The above mentioned two way binding doesn't always work well with all <interactivity:Interaction.Behaviors> <core:EventTriggerBehavior EventName="SelectionChanged"> <core:InvokeCommandAction Command="{Binding Children.UpdatePropertyFiltersCommand}"> <core:InvokeCommandAction.CommandParameter> <controls and complex bindings:KeyValueList> <controls:KeyValueParameter Key="ClearPropertyFilters" Value="false" /> <controls:KeyValueParameter Key="STATUSCOLOR" Value="{Binding SelectedItem. In such casesDisplayText, the alternative is to use the UpdatePropertyFiltersCommand to supply the filter criteriaElementName=ComboBox}" /> </controls:KeyValueList> </core:InvokeCommandAction.CommandParameter> </core:InvokeCommandAction> </core:EventTriggerBehavior> </interactivity:Interaction.Behaviors></controls:ComboBoxExt></source> </tab> <tab name="Xamarin"><source lang = "xml">xmlns:controls="clr-namespace:UBIK.CPL.Controls;assembly=UBIK.CPL"xmlns:classes="clr-namespace:UBIK.CPL.Classes;assembly=UBIK.CPL">

<tab nameNote that you will then need to remove references to the DisplayText, as the x:String value becomes the value used to filter. ="Xamarin">=== GUID Properties ====The above controls:ComboBoxExt and controls:PickerExt examples can be converted to filter GUID values as follows:

<Grid xmlnsXamarin:ctrls="clr-namespace:UBIK.CPL.Controls;assembly=UBIK.CPL" xmlns:classes="clr-namespace:UBIK.CPL.Classes;assembly=UBIK.CPL"> <ctrlscontrols:PickerExt x:Name="FilterPlant_Filter" ItemsSource="{Binding Properties.AllItems[QUERYLK_PLANT_QUERY].LinkedLevel.Children.Items}" ItemDisplayBinding="{Binding Header}" SelectionChangedCommand="{Binding Children.UpdatePropertyFiltersCommand}" SelectedValuePath="UID" SelectedValue="{Binding Children.Filters[STALK_PLANT_SECTION].Value, Mode=OneWay}"> <ctrlscontrols:PickerExt.SelectionChangedCommandParameter> <classes:KeyValueList> <classes:KeyValueParameter Key="ClearPropertyFilters" Value="false" /> <classes:KeyValueParameter Key="STALK_PLANT_SECTION" Value="{Binding Path=SelectedItem.UID, Source={x:Reference FilterPlant_Filter}, Converter={StaticResource FilterValueToCriterion}, ConverterParameter=Content[\&quot;\{0\}\&quot;].Value.ToString().Equals(\&quot;\{1\}\&quot;)\=\=true}" /> </classes:KeyValueList> </ctrlscontrols:PickerExt.SelectionChangedCommandParameter> </ctrlscontrols:PickerExt></Grid>

</tabbr>Note that in this example, a Properties.AllItems[LK_PLANT_QUERY] is added to the Content object to provide the list of items displayed by the Picker, as a workaround to the Children.Items[0] approach.<br><br>

<tab name="UWP">= Displaying Results ==Not yet available.<For performance/tab>usability reasons, the result list is not immediately refreshed as one types in the text box. Instead, it only happens after the ReloadChildListCommand is triggered.

This can be done on a dedicated button:</tabssource lang = "xml">UWP:

The example above uses a UBIK.CPL.Controls.PickerExt control to display a list of query result objects (through the <Button Content="QUERY{Binding Filter, Source={StaticResource UBIKIcons}}" property's LinkedLevel). The UID of the selected object is then passed on as a part of the command parameter and later used as a filter criterion to filter for objects that have their Style="{StaticResource UBIKSymbolButtonStyle}" Command="STA{Binding ReloadChildListCommand}" property value containing the UID string./>* ClearPropertyFilters: Clear out all existing filters at the current level before executing the command. This is optional and defaults to false;</source>* All other parameters: Used as filter criteria where the Keys are the names of the properties by which you want to filter.<br>

<classes:KeyValueParameter Key="STA" Value="{Binding Path=SelectedItem.UID, Source={x:Reference Filter}, Converter={StaticResource FilterValueToCriterion}, ConverterParameter=Content[\&quot;\{0\}\&quot;].Value.ToString().Equals(\&quot;\{1\}\&quot;)\=\=true}" />

<br> {{Hint|"&amp;quot;" and "\" are used for escaping the special characters in XAML and C# code respectively. "{0}" and "{1}" are placeholders and get replaced by the property name and the filter value. The end expression being executed in this example is <code>Content["PROPERTY_NAME"].Value.ToString().Equals(FILTER_VALUE)&#61;&#61;true</code>}}<br><br> == UI Customizing == === Filtered Indicator ===You can also customize UI elements to indicate that filters are active.<source lang = "xml">UWP: <Border Background="#8000488E" Visibility="{Binding Children.Filters[SomePropertyName], Converter={StaticResource NullObjOrEmptyStrColConverter}}" /></source><br>The above border is shown when a filter is active. Other bindings exist on the Filters collection. Use [[Developer_Mode|Developer Mode]] to see what possibilities are available. Some examples are:<source lang = "xml">Children.Filters.Filters.Count</source><br><source lang = "xml">Children.Filters.IsActive</source><br><br> == Troubleshooting ==As previously mentioned, only areas with a custom Child Area template name can make use of filters.When Filters (or Sorting) are applied, a config file is created at '''Local State/Configs''' where the filter data is written and persisted. {{Attention|Note that during a trial and error phase, filters may be applied that makes a child list fully/partially filtered out of view. }}This file can be used to inspect how a xaml implementation is being translated into filter criteria.

{{Category/Version|2Deleting the file (with the client closed) will remove forget any filters.6.1}}