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Difference between revisions of "Property Based Content Filters"

(Refactoring of article layout for clarity. Added some missing xaml impls)
(Added sections on Displaying Results, and Troubleshooting)
Line 8: Line 8:
 
* Require a custom [[SYSCLS_CHILDAREATEMPLATE|Child Area template name]] to work. This customizing will not work applied to the UBIKChildArea.
 
* Require a custom [[SYSCLS_CHILDAREATEMPLATE|Child Area template name]] to work. This customizing will not work applied to the UBIKChildArea.
 
* 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.
 
* 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>
+
<br>
  
 
== Usage ==
 
== Usage ==
Line 42: Line 42:
 
  <tab name="UWP">
 
  <tab name="UWP">
 
<source lang = "xml">
 
<source lang = "xml">
 +
xmlns:controls="using:UBIK.WinX.Controls"
 +
xmlns:core="using:Microsoft.Xaml.Interactions.Core"
 +
xmlns:interactivity="using:Microsoft.Xaml.Interactivity"
 +
 
<controls:ComboBoxExt
 
<controls:ComboBoxExt
 
     x:Name="ComboBox"
 
     x:Name="ComboBox"
−
     PlaceholderText="{Binding Children.Filters[STATUSCOLOR].Value, FallbackValue='SELECT'}"
+
     PlaceholderText="{Binding Children.Filters[STATUSCOLOR].Value, TargetNullValue='SELECT', FallbackValue='SELECT'}"
 
     DisplayMemberPath="DisplayText"
 
     DisplayMemberPath="DisplayText"
 
     SelectedValuePath="DisplayText"
 
     SelectedValuePath="DisplayText"
Line 71: Line 75:
 
* PlaceholderText binds to the same value as your SelectedValueExt to display the current selected item. This is a workaround for a failure of the ComboBox control to correctly display an active selection when the control is rendered.
 
* PlaceholderText binds to the same value as your SelectedValueExt to display the current selected item. This is a workaround for a failure of the ComboBox control to correctly display an active selection when the control is rendered.
 
  </tab>
 
  </tab>
 +
 
  <tab name="Xamarin">
 
  <tab name="Xamarin">
 
  </tab>
 
  </tab>
 
<source lang = "xml">
 
<source lang = "xml">
−
xmlns:ctrls="clr-namespace:UBIK.CPL.Controls;assembly=UBIK.CPL"
+
xmlns:controls="clr-namespace:UBIK.CPL.Controls;assembly=UBIK.CPL"
 
xmlns:classes="clr-namespace:UBIK.CPL.Classes;assembly=UBIK.CPL">
 
xmlns:classes="clr-namespace:UBIK.CPL.Classes;assembly=UBIK.CPL">
  
−
<ctrls:PickerExt
+
<controls:PickerExt
 
     x:Name="Filter"
 
     x:Name="Filter"
 
     ItemsSource="{Binding Properties.AllItems[QUERY].LinkedLevel.Children.Items}"
 
     ItemsSource="{Binding Properties.AllItems[QUERY].LinkedLevel.Children.Items}"
Line 99: Line 104:
 
* ClearPropertyFilters: Clear out all existing filters at the current level before executing the command. This is optional and defaults to false;
 
* ClearPropertyFilters: Clear out all existing filters at the current level before executing the command. This is optional and defaults to false;
 
* All other parameters: KeyValue pairs used as filter criteria where the Keys are the names of the metaproperties by which you want to filter.
 
* All other parameters: KeyValue pairs used as filter criteria where the Keys are the names of the metaproperties by which you want to filter.
 +
<br>
 +
 +
=== Displaying Results ===
 +
For performance/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:
 +
<source lang = "xml">
 +
UWP:
 +
 +
<Button 
 +
    Content="{Binding Filter, Source={StaticResource UBIKIcons}}"
 +
    Style="{StaticResource UBIKSymbolButtonStyle}"
 +
    Command="{Binding ReloadChildListCommand}"/>
 +
</source>
 +
<br>
 +
 +
Or in certain cases, can be combined with the filter input to trigger immediately:
 +
<source lang = "xml">
 +
Xamarin:
 +
 +
<Entry.Behaviors>
 +
    <behaviors:EventHandlerBehavior EventName="Completed">
 +
        <behaviors:InvokeCommandAction Command="{Binding ReloadChildListCommand}" />
 +
    </behaviors:EventHandlerBehavior>
 +
</Entry.Behaviors>
 +
</source>
  
 
<br>
 
<br>
Line 107: Line 138:
  
 
In more advanced scenarios where a different type of comparison is needed, the example (or more specifically the one KeyValueParameter) can be extended into the following, e.g. comparing whether the specified filter value is equal to the value of the property.
 
In more advanced scenarios where a different type of comparison is needed, the example (or more specifically the one KeyValueParameter) can be extended into the following, e.g. comparing whether the specified filter value is equal to the value of the property.
−
 
+
<source lang = "xml">
 
<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}" />
 
<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}" />
 
</source>
 
</source>
 +
</source>
 +
<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>}}
 
{{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>}}
Line 116: Line 149:
  
 
== UI Customizing ==
 
== UI Customizing ==
−
 
−
=== Update Child List ===
 
−
For performance/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.
 
  
 
=== Filtered Indicator ===
 
=== Filtered Indicator ===
 
You can also customize UI elements to indicate that filters are active.
 
You can also customize UI elements to indicate that filters are active.
 
<source lang = "xml">
 
<source lang = "xml">
−
<Border Background="#8000488E" Visibility="{Binding Children.Filters[SomePropertyName], Converter={StaticResource NullObjOrEmptyStrColConverter}}" />
+
UWP:
 +
 
 +
<Border  
 +
    Background="#8000488E"  
 +
    Visibility="{Binding Children.Filters[SomePropertyName], Converter={StaticResource NullObjOrEmptyStrColConverter}}" />
 
</source>
 
</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.
  
−
UWP: The above border is shown when a filter is active.
+
Deleting the file (with the client closed) will remove forget any filters.
  
 
[[Category:2.6.1|Property Based Content Filters]]
 
[[Category:2.6.1|Property Based Content Filters]]

Revision as of 10:14, 27 June 2024

The UI can be customized to accept user inputs as filter criteria, and reduce the entire child list to a sub-list based on property values that contain that text. Each filter is 'attached' to a single metaproperty, and multiple filters can be applied at once.

IC Hint square.pngWhen multiple filters are used at the same time, they are combined with "logic and".

For performance/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.

However, note that these content-based filters:

  • Require a custom Child Area template name to work. This customizing will not work applied to the UBIKChildArea.
  • 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 ListCollectionView / sfDataSourceExt) will also be affected.


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

UWP

<TextBox
   Text="{Binding Children.Filters[SomePropertyName], Mode=TwoWay, Converter={StaticResource FilterCriterionToValueConverter}}"
   PlaceholderText="SomePropertyName" />

Xamarin

<Entry
   Placeholder="Filter by Name"
   Text="{Binding Children.Filters[DESCR], Mode=TwoWay, Converter={StaticResource FilterCriterionToValue}}"/>

This is shown as a single text box. The two way binding on Text allows the entered text (case insensitive) to be used as the filter value on property "SomePropertyName" (case sensitive).

Selection

Selection is trickier to achieve than direct input, as often a metaproperty's actual value might differ from the text that is displayed for that value. Just think of integer-based statuses, or GUID properties.

UWP

xmlns:controls="using:UBIK.WinX.Controls"
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="{Binding Children.Filters[STATUSCOLOR].Value}"
   SelectedValueExt="{Binding Children.Filters[STATUSCOLOR].Value}"
   ItemsSource="{Binding Children.Items[1].Properties.AllItems[STATUSCOLOR].MetaProperty.SelectiveList, Converter={StaticResource SelectiveListToItemsConverter}}">

    <interactivity:Interaction.Behaviors>
        <core:EventTriggerBehavior EventName="SelectionChanged">
            <core:InvokeCommandAction Command="{Binding Children.UpdatePropertyFiltersCommand}">                                               
                <core:InvokeCommandAction.CommandParameter>
                    <controls:KeyValueList>
                        <controls:KeyValueParameter Key="ClearPropertyFilters" Value="false" />
                        <controls:KeyValueParameter Key="STATUSCOLOR" Value="{Binding SelectedItem.DisplayText, ElementName=ComboBox}" />
                    </controls:KeyValueList>
                </core:InvokeCommandAction.CommandParameter>
            </core:InvokeCommandAction>
        </core:EventTriggerBehavior>
    </interactivity:Interaction.Behaviors>
</controls:ComboBoxExt>

Note that several elements are required for this customization to work:

  • SelectedValuePath informs the control of which property should be supplied to the command as a filter criteria. This should match what is supplied in your KeyValueParameter.
  • DisplayMemberPath informs the control of which property should be visualized as the displaytext of your selection.
  • PlaceholderText binds to the same value as your SelectedValueExt to display the current selected item. This is a workaround for a failure of the ComboBox control to correctly display an active selection when the control is rendered.

Xamarin

xmlns:controls="clr-namespace:UBIK.CPL.Controls;assembly=UBIK.CPL"
xmlns:classes="clr-namespace:UBIK.CPL.Classes;assembly=UBIK.CPL">

<controls:PickerExt
   x:Name="Filter"
   ItemsSource="{Binding Properties.AllItems[QUERY].LinkedLevel.Children.Items}"
   ItemDisplayBinding="{Binding Header}"
   SelectionChangedCommand="{Binding Children.UpdatePropertyFiltersCommand}"
   SelectedValuePath="UID"
   SelectedValue="{Binding Children.Filters[STA].Value, Mode=OneWay}">
    <ctrls:PickerExt.SelectionChangedCommandParameter>
        <classes:KeyValueList>
            <classes:KeyValueParameter Key="ClearPropertyFilters" Value="false" />
            <classes:KeyValueParameter Key="STA" Value="{Binding Path=SelectedItem.UID, Source={x:Reference Filter}}" />
        </classes:KeyValueList>
    </ctrls:PickerExt.SelectionChangedCommandParameter>
</ctrls:PickerExt>

The example above uses a custom ComboBox/Picker control to display a list of items. The chosen aspect of the 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 the same the string.

This approach makes use of the Children.UpdatePropertyFiltersCommand, which uses the following parameters:

  • ClearPropertyFilters: Clear out all existing filters at the current level before executing the command. This is optional and defaults to false;
  • All other parameters: KeyValue pairs used as filter criteria where the Keys are the names of the metaproperties by which you want to filter.


Displaying Results

For performance/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:

UWP:

<Button  
   Content="{Binding Filter, Source={StaticResource UBIKIcons}}"
   Style="{StaticResource UBIKSymbolButtonStyle}"
   Command="{Binding ReloadChildListCommand}"/>


Or in certain cases, can be combined with the filter input to trigger immediately:

Xamarin:

<Entry.Behaviors>
    <behaviors:EventHandlerBehavior EventName="Completed">
        <behaviors:InvokeCommandAction Command="{Binding ReloadChildListCommand}" />
    </behaviors:EventHandlerBehavior>
</Entry.Behaviors>


Evaluation Criteria

By default, the expression used for filtering is Content["PROPERTY_NAME"].DisplayValue.ToLower().Contains(FILTER_VALUE.ToLower())==true. In other words, it checks whether the specified filter value (as string) is contained in the display value of the property.

In more advanced scenarios where a different type of comparison is needed, the example (or more specifically the one KeyValueParameter) can be extended into the following, e.g. comparing whether the specified filter value is equal to the value of the property.

<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}" />

</source>

IC Hint square.png"&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 Content["PROPERTY_NAME"].Value.ToString().Equals(FILTER_VALUE)==true



UI Customizing

Filtered Indicator

You can also customize UI elements to indicate that filters are active.

UWP:

<Border
   Background="#8000488E"
   Visibility="{Binding Children.Filters[SomePropertyName], Converter={StaticResource NullObjOrEmptyStrColConverter}}" />


The above border is shown when a filter is active.

Other bindings exist on the Filters collection. Use Developer Mode to see what possibilities are available. Some examples are:

Children.Filters.Filters.Count


Children.Filters.IsActive



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.

IC Attention.pngNote 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.

Deleting the file (with the client closed) will remove forget any filters.

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