Single-selection tree

Availability

[SINCE Orbeon Forms 2017.1]

NOTE: As of Orbeon Forms 2017.1, this control is not present in the Form Builder toolbox because Form Builder lacks the ability to created hierarchical itemsets, making this control less useful in that context.

What it does

This control allows the user to select a single item from a hierarchical tree representation.

Appearance

Basic usage

You:

  • specify appearance="tree" on an <xf:select1> control
  • generally use an <xf:itemset> element to point to items which are organized in a hierarchy
<xf:select1 appearance="tree" ref="instance('tree-items')">
    <xf:itemset ref="instance('tree-items')//item">
        <xf:label ref="@label"/>
        <xf:value ref="@value"/>
    </xf:itemset>
</xf:select1>

The tree-items instance might look like:

<xf:instance id="tree-items">
    <items>
        <choices>
            <item label="Item 1" value="1">
                <item label="Item 1.1" value="1.1">
                    <item label="Item 1.1.1" value="1.1.1">
                        <item label="Item 1.1.1.1" value="1.1.1.1"/>
                        <item label="Item 1.1.1.2" value="1.1.1.2"/>
                    </item>
                    <item label="Item 1.1.2" value="1.1.2">
                        <item label="Item 1.1.2.1" value="1.1.2.1"/>
                        <item label="Item 1.1.2.2" value="1.1.2.2"/>
                    </item>
                </item>
                <item label="Item 1.2" value="1.2">
                    <item label="Item 1.2.1" value="1.2.1">
                        <item label="Item 1.2.1.1" value="1.2.1.1"/>
                        <item label="Item 1.2.1.2" value="1.2.1.2"/>
                    </item>
                </item>
            </item>
            <item label="Item 2" value="2">
                <item label="Item 2.1" value="2.1">
                    <item label="Item 2.1.1" value="2.1.1">
                        <item label="Item 2.1.1.1" value="2.1.1.1"/>
                        <item label="Item 2.1.1.2" value="2.1.1.2"/>
                        <item label="Item 2.1.1.3" value="2.1.1.3"/>
                    </item>
                </item>
                <item label="Item 2.2" value="2.2">
                    <item label="Item 2.2.1" value="2.2.1"/>
                    <item label="Item 2.2.2" value="2.2.2"/>
                </item>
            </item>
        </choices>
    </items>
</xf:instance>

The user can expand or collapse tree nodes. This doesn't have an impact on the currently-selected value:

Expanded tree

Readonly appearance

If the control is readonly, it appears grayed out. It is not possible to select items in this case, but it is possible to open/close tree nodes:

Expanded tree in readonly mode

Controlling which tree nodes are initially open

The <xf:itemset> element supports the xxf:open extension attribute, which determines which nodes of the tree are open when the tree is first rendered. You can use <xf:itemset xxf:open="true"> if you want all the nodes to be open. If you have a condition under which nodes should be open, use an AVT. For instance, the following will open just the first level of the tree. If you wanted to open all the nodes up to 3 levels of depth, you would instead write {count(ancestor-or-self::item) le 3}.

<xf:select ref="value">
    <xf:itemset
            ref="instance('tree-items')//item"
            xxf:open="{count(ancestor-or-self::item) = 1}">
        <xf:label ref="@label"/>
        <xf:value ref="@value"/>
    </xf:itemset>
</xf:select>

The result:

Tree with first level open only

Adding class attributes

You can use an AVT in the the class attribute on the <xf:itemset> element to produce different CSS classes for different nodes.

class="my-class-{position()}"

Static readonly mode

When used in Form Runner's readonly modes, the control doesn't show a tree but a field with the label associated with the user selection.

Custom styling

As of Orbeon Forms 2017.1, the implementation of the tree appearance uses the Fancytree JavaScript library.

NOTE: This is subject to change in new versions of Orbeon Forms.

However you can look at the markup produced by Fancytree with your browser's development tools and apply custom CSS to style the tree. All icons are set with CSS. Here is an example of the HTML layout:

 <ul class="ui-fancytree fancytree-container fancytree-plain" tabindex="0">
    <li class="">
        <span class="fancytree-node fancytree-expanded fancytree-folder fancytree-has-children fancytree-exp-e fancytree-ico-ef">
            <span class="fancytree-expander"/>
            <span class="fancytree-icon"/>
            <span class="fancytree-title">Item 1</span>
        </span>
        <ul>
            <li class="">
                <span class="fancytree-node fancytree-folder fancytree-has-children fancytree-exp-c fancytree-ico-cf">
                    <span class="fancytree-expander"/>
                    <span class="fancytree-icon"/>
                    <span class="fancytree-title">Item 1.1</span>
                </span>
            </li>
            <li class="fancytree-lastsib">
                <span class="fancytree-node fancytree-folder fancytree-has-children fancytree-lastsib fancytree-exp-cl fancytree-ico-cf">
                    <span class="fancytree-expander"/>
                    <span class="fancytree-icon"/>
                    <span class="fancytree-title">Item 1.2</span>
                </span>
            </li>
        </ul>
    </li>
    <li class="fancytree-lastsib">
        <span class="fancytree-node fancytree-expanded fancytree-folder fancytree-has-children fancytree-lastsib fancytree-exp-el fancytree-ico-ef">
            <span class="fancytree-expander"/>
            <span class="fancytree-icon"/>
            <span class="fancytree-title">Item 2</span>
        </span>
        <ul>
            <li class="">
                <span class="fancytree-node fancytree-folder fancytree-has-children fancytree-exp-c fancytree-ico-cf">
                    <span class="fancytree-expander"/>
                    <span class="fancytree-icon"/>
                    <span class="fancytree-title">Item 2.1</span>
                </span>
            </li>
            <li class="fancytree-lastsib">
                <span class="fancytree-node fancytree-folder fancytree-has-children fancytree-lastsib fancytree-exp-cl fancytree-ico-cf">
                    <span class="fancytree-expander"/>
                    <span class="fancytree-icon"/>
                    <span class="fancytree-title">Item 2.2</span>
                </span>
            </li>
        </ul>
    </li>
</ul>

See tree-select1.less for the style applied by Orbeon Forms as of version 2017.1.

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