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Single selection tree |  |
Multiple selection tree |  |
Usage & Behaviour
The tree is used to navigate within hierarchical lists of objects (e.g. organizations), and then to select one or more items in order to filter content or show additional information.
It usually appears inside a Filter Pane, a Details Panel or a Widget.
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Nodes should be ordered alphabetically, to allow users locating specific objects quickly.
An exception to this guideline are time-related objects, that should be ordered chronologically, with the most recent item first.
Logical: Sort items into a meaningful order. Group related options together and show the most common options first, followed by less common options.
Alphabetical: Sort the options alphabetically if more than 8 select options are available. This helps the user find the right option quickly. Sort currencies, names, and similar content alphabetically.
Numeric:Sort numeric values into a sequential order, with the lowest number first.
Chronological:Sort time-related information into chronological order, with the most recent first.
States
Regular |  |
Hover |  |
Active |  |
Disabled | |
Focused |  |
Focused, Hover | |
Focused, Active | |
Focused, Disabled |
Interaction
You can click on the entire label
Click on the expand/collapse toggle will do the respective action.
Click on the node label (+counter) will select the node
Double-clicking the container node will expand/collapse the node
When the label is truncated (node name), hovering over it will show a tooltip with the full label
When a user expands a node if the nodes are not shown immediately, provide a "loading" indication at the place below the expanded node.
Selecting:Hovering over a truncated node title will show a tooltip containing the full title.
Clicking a node (including the title and the icon, if exists) selects it. This will unselect any previously selected node.
Clicking a triangle toggle button or double-clicking a container node will:
toggle between collapsed and expanded state of the node. In case loading the content of the node takes more than 1 second, a Progress Indicator will appear.
toggle the button between states.
In case of multiple selection:
Clicking a checkbox will check / uncheck the item, including all child items if exists, regardless of other selections.
In case not all child items are selected, the parent item’s state will be state to partially selected.
For more information about selecting items, see lists.
Single select: One item of the tree can be selected. To select an item, click anywhere on the item row.
Multiple selections: Allow the selection of one or more items. For this, the tree provides checkboxes on the left side of each line item. Each item is selected independently of the others
Single Selection | Multiple Selection Mode |
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Single selection is activated by selecting the node label. Selecting the node label will select the node and un-select previously selected node. | On mouse hover a node, a check box is displayed. If the user checks it he is placed in a multi selection mode. Multi selection mode can also be activated by using Ctrl/Shift while selecting the node label. On this mode, clicking the label/check box will perform multi select. Only once the apply is pressed the action is executed (whatever the corresponding action is). Selecting a parent node through the check box will select its descendants as well. Unselecting some of the descendants will place the parent node in mixed state. |
Drag and drop, Please refer to the Drag and drop pattern
Best practices
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Where there is no real hierarchy → use a List instead
to select values in a form or where the number of items is small → use a Drop-down Menu instead
General:
Tree may need to be 3, 4, or even 5 levels deep. But if you have 15-20 levels of depth it suffers usabilityTry to avoid trees with too many hierarchy levels. How many are reasonable?
In case of a long list add a Search component.
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