Configuration

An object defining configuration options for the TreeView widget.

accessKey

Specifies a shortcut key that sets focus on the widget element.

Type: String
Default Value: null

The accessKey option value is passed to the accesskey attribute of the actual HTML element of the widget.

activeStateEnabled

A Boolean value specifying whether or not the widget changes its state when interacting with a user.

Type: Boolean
Default Value: false

This option is used when the widget is displayed on a platform whose guidelines include the active state change for widgets.

animationEnabled

Specifies whether or not to animate item collapsing and expanding.

Type: Boolean
Default Value: true

Show Example:
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dataSource

A data source used to fetch data to be displayed by the widget.

Default Value: null

This option accepts one of the following.

  • Array of objects
    A simple JavaScript array containing a collection of plain objects.

  • URL
    A URL to JSON data or to a service returning data in JSON format.

  • DataSource or its configuration object
    A DataSource is an object that provides a handy API for data processing. A DataSource is a stateful object, which means that it saves data processing settings and applies them each time data is loaded. All underlying data access logic of a DataSource is isolated in a Store. A Store provides an API for reading and modifying data. Unlike the DataSource, a Store is a stateless object.

NOTE
The widget requires each data item to have a key field whose value is unique within the entire array.
NOTE
If the data source is specified using the dataSource option, use the items option only for reading. Updating data items using the items option may cause unexpected results.

To display widget items, a default template can be used. This template is based on the data source fields that are listed in the Default Item Template section of the widget's API. Alternatively, you can implement a custom item template. For details, refer to the Customize Widget Element Appearance topic.

dataStructure

Specifies whether a nested or plain array is used as a data source.

Type: String
Default Value: 'tree'
Accepted Values: 'tree' | 'plain'

If the option is set to 'tree', the array should have a tree structure. It means that each item can contain the items field, which contains an array of nested items.

JavaScript
var treeViewData = [
    {
        id: 1,
        items: [
            { id: 11 },
            { id: 12 },
            { 
                id: 13,
                items: [
                    { id: 131 },
                    { id: 132 },
                    { id: 133 },
                ]
            },
        ]
    },
    { id: 2 }
];

If the dataStructure option value is 'plain', the array should have a plain structure. In this case, each array item should contain the parentId field, which specifies the key of the parent item.

JavaScript
var treeViewData = [
    { id: 1, parentId: 0 },
    { id: 11, parentId: 1 },
    { id: 12, parentId: 1 },
    { id: 13, parentId: 1 },
    { id: 131, parentId: 13 },
    { id: 132, parentId: 13 },
    { id: 133, parentId: 13 },
    { id: 2, parentId: 0 }
];
NOTE
If the dataStructure option is set to 'plain', the widget requires you to specify at least one root item. An item is used as a root item if its parentId field holds 0 or null.
NOTE
The widget requires each data item to have a key field whose value is unique within the entire array.
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disabled

A Boolean value specifying whether or not the widget can respond to user interaction.

Type: Boolean
Default Value: false

Create an observable variable and assign it to this option to specify the availability of the widget at runtime.

disabledExpr

Specifies the name of the data source item field whose value defines whether or not the corresponding widget item is disabled.

Default Value: 'disabled'

displayExpr

Specifies the name of the data source item field whose value is displayed by the widget.

Default Value: 'text'

expandAllEnabled

Specifies whether or not a user can expand all tree view items by the "*" hot key.

Type: Boolean
Default Value: false

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expandedExpr

Specifies the name of the data source item field whose value defines whether or not the corresponding widget item is displayed expanded.

Default Value: 'expanded'

expandNodesRecursive

Specifies whether or not all parent nodes of an initially expanded node are displayed expanded.

Type: Boolean
Default Value: true

focusStateEnabled

Specifies whether or not the widget can be focused.

Type: Boolean
Default Value: false
Default for desktop: true

hasItemsExpr

Specifies the name of the data source item field whose value defines whether or not the corresponding node includes child nodes.

Default Value: 'hasItems'

height

Specifies the height of the widget.

Return Value: Number|String

The widget height.

Default Value: undefined

The option can hold a value of the following types.

  • number
    The height of the widget in pixels

  • string
    A CSS measurement of the widget height (e.g., "55px", "80%", "auto" and "inherit")

  • function
    A function returning the widget height, e.g.,

    JavaScript
    height: function () {
        return baseHeight - 10 + "%";
    });

hint

Specifies the text of the hint displayed for the widget.

Type: String
Default Value: undefined

hoverStateEnabled

A Boolean value specifying whether or not the widget changes its state when being hovered by an end user.

Type: Boolean
Default Value: true

itemHoldTimeout

The time period in milliseconds before the onItemHold event is raised.

Type: Number
Default Value: 750

items

An array of items displayed by the widget.

Type: Array
NOTE
The widget requires each data item to have a key field whose value is unique within the entire array.

You can use the dataSource option instead. Unlike the items option, the dataSource option can take on the DataSource configuration object as well as a simple array.

NOTE
If you need to modify the data source specified using the items option at runtime, do it only with the help of the items option. Updating data items using the dataSource option may cause unexpected results.

To display widget items, a default template can be used. This template is based on the data source fields that are listed in the Default Item Template section of the widget's API. Alternatively, you can implement a custom item template. For details, refer to the Customize Widget Element Appearance topic.

itemsExpr

Specifies the name of the data source item field that contains an array of nested items.

Default Value: 'items'

This option is used if the dataStructure option value is 'tree'.

itemTemplate

The template to be used for rendering items.

Type: template
Function parameters:
itemData: Object

The item object to be rendered.

itemIndex: Number

The index of the item to be rendered.

itemElement: jQuery

An HTML element of the item to be rendered.

Return Value: String|DOM Node|jQuery

A template name or a template container.

Default Value: 'item'

A binding context of an item template is the data source object that corresponds to the currently rendered item.

In Knockout approach, you can bind template elements to the item object's fields directly. To access another binding context within an item template, use Knockout binding variables.

In AngularJS Approach, if you need to access item object's fields within a template, use a variable whose name is assigned to the dx-item-alias directive. Add the directive to the widget element to specify an alias to the root object of an item. Without this directive, item object fields are beyond reach. To access another binding context within an item template, use AngularJS binding variables.

See Also

keyExpr

Specifies the name of the data source item field used as a key.

Default Value: 'id'
NOTE
The key value should be unique within the data array.

View Demo

noDataText

The text or HTML markup displayed by the widget if the item collection is empty.

Type: String
Default Value: 'No data to display'

onContentReady

A handler for the contentReady event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

Default Value: null

Assign a function to perform a custom action when widget content is ready.

onDisposing

A handler for the disposing event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

Default Value: null

Assign a function to perform a custom action when the widget is being removed.

NOTE
The function assigned to this option is executed only if the widget is removed using the remove(), empty(), or html() jQuery methods.

onInitialized

A handler for the initialized event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

Default Value: null

Assign a function to perform a custom action when the widget is initialized.

onItemClick

A handler for the itemClick event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

itemData: Object

The data that is bound to the clicked item.

itemElement: jQuery

An HTML element of the item.

itemIndex: Number

Specifies the index of the clicked item.

node: Object

The item node.

Default Value: null

Assign a function to perform a custom action when a widget item is clicked.

To navigate to a specific URL when the itemClick event fires, assign that URL or the anchor part (#) of that URL directly to this option as a string.

onItemCollapsed

A handler for the itemCollapsed event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

itemData: Object

The data that is bound to the clicked item.

itemElement: jQuery

An HTML element of the item.

itemIndex: Number

Specifies the index of the collapsed item.

jQueryEvent: jQuery.Event

Specifies the jQuery event that caused action execution.

node: Object

The collapsed item node.

Default Value: null

Assign a function to perform a custom action when a tree view item is collapsed.

onItemContextMenu

A handler for the itemContextMenu event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

itemData: Object

The data that is bound to the item.

itemElement: jQuery

An HTML element of the item.

itemIndex: Number

Specifies the index of the item.

jQueryEvent: jQuery.Event

Specifies the jQuery event that caused action execution.

node: Object

The item node.

Default Value: null

Assign a function to perform a custom action when the right mouse button is clicked when the pointer is over a widget item, or when the "sustained" (also known as a long press) touch action is performed.

onItemExpanded

A handler for the itemExpanded event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

itemData: Object

The data that is bound to the expanded item.

itemElement: jQuery

An HTML element of the item.

itemIndex: Number

Specifies the index of the expanded item.

jQueryEvent: jQuery.Event

Specifies the jQuery event that caused action execution.

node: Object

The expanded item node.

Default Value: null

Assign a function to perform a custom action when a tree view item is expanded.

onItemHold

A handler for the itemHold event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

itemData: Object

The data that is bound to the item being held.

itemElement: jQuery

An HTML element of the item.

itemIndex: Number

Specifies the index of the item being held.

node: Object

The item node.

Default Value: null

Assign a function to perform a custom action when the widget's collection item is being held for a specified time period (see the itemHoldTimeout option).

onItemRendered

A handler for the itemRendered event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

itemData: Object

The data that is bound to the item to be rendered.

itemElement: jQuery

An HTML element of the item.

itemIndex: Number

Specifies the index of the rendered item.

node: Object

The item node.

Default Value: null

Assign a function to perform a custom action after a collection item is rendered.

onItemSelected

Deprecated

Use the onItemSelectionChanged option instead.

A handler for the itemSelected event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

node: Object

A node of the selected item.

Default Value: null

Assign a function to perform a custom action when a tree view item is selected.

View Demo

onItemSelectionChanged

A handler for the itemSelectionChanged event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

node: Object

A node of the selected item.

Default Value: null

This option makes sense in one of the following cases.

  1. The selectByClick option is set to true.
  2. The showCheckBoxesMode option is not set to 'none'.
  3. You use one of the methods: selectAll, unselectAll, selectItem, unselectItem.

onOptionChanged

A handler for the optionChanged event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

name: String

Specifies the name of the option whose value is changed.

fullName: String

Specifies a full name of the option whose value is changed. The full name is formed by concatenating the names of the options that are presented in the hierarchy of the given option. The names are delimited by commas.

value: any

Specifies a new value for the option.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

Default Value: null

Assign a function to perform a custom action after an option of the component is changed.

onSelectionChanged

A handler for the selectionChanged event.

Type: function
Function parameters:

Provides function parameters.

Object structure:
component: Object

Provides access to the widget instance.

element: jQuery

An HTML element of the widget.

model: Object

Provides access to the data that is available for binding against the element. Available only in the Knockout approach.

Default Value: null

Assign a function to perform a custom action when the selection changes.

This option makes sense in one of the following cases.

  1. The selectByClick option is set to true.
  2. The showCheckBoxesMode option is not set to 'none'.
  3. You use one of the methods: selectAll, unselectAll, selectItem, unselectItem.

parentIdExpr

Specifies the name of the data source item field for holding the parent key of the corresponding node.

Default Value: 'parentId'

This option is used if the dataStructure option is set to 'plain'.

View Demo

rootValue

Specifies the parent ID value of the root item.

Type: Object
Default Value: 0

rtlEnabled

Specifies whether or not the current component supports a right-to-left representation.

Type: Boolean
Default Value: false

If you need to switch the display of this DevExtreme component to right-to-left, enable a specifically designed configuration option - rtlEnabled. When this option is set to true, the text flows from right to left, and the layout the component's elements is reversed. To switch the entire application/site to a right-to-left representation, use the static DevExpress.rtlEnabled field.

scrollDirection

A string value specifying available scrolling directions.

Type: String
Default Value: 'vertical'
Accepted Values: 'vertical' | 'horizontal' | 'both'

searchValue

Specifies the current value used to filter tree view items.

Type: String
Default Value: ''

If this option holds a non-empty string, the tree view displays only items containing this string and their parent items.

NOTE
When the virtual mode is enabled, the TreeView filters only the currently loaded items.
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selectAllEnabled

Deprecated

Use the showCheckBoxesMode options instead.

Specifies whether the "Select All" check box is displayed over the tree view.

Type: Boolean
Default Value: false

Use this option only if the showCheckBoxes option value is true.

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selectAllText

Specifies the text displayed at the "Select All" check box.

Type: String
Default Value: 'Select All'

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selectByClick

Specifies whether or not an item becomes selected if a user clicks it.

Type: Boolean
Default Value: false

selectedExpr

Specifies the name of the data source item field whose value defines whether or not the corresponding widget items is selected.

Default Value: 'selected'

selectionMode

Specifies item selection mode.

Type: String
Default Value: 'multiple'
Accepted Values: 'single' | 'multiple'

selectNodesRecursive

Specifies whether or not to select nodes recursively.

Type: Boolean
Default Value: true

If this option is enabled, the widget selects (unselects) all child nodes if a user selects (unselects) the parent node.

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showCheckBoxes

Deprecated

Use the showCheckBoxesMode options instead.

Specifies whether or not a check box is displayed at each tree view item.

Type: Boolean
Default Value: false
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showCheckBoxesMode

Specifies the current check boxes display mode.

Type: String
Default Value: 'none'
Accepted Values: 'none' | 'normal' | 'selectAll'

The option accepts the following values.

  • 'none'
    The widget does not display check boxes.

  • 'normal'
    The widget displays a check box for each item.

  • 'selectAll'
    The widget displays a check box for each item and the 'select all' check box at the top of the widget.

tabIndex

Specifies the widget tab index.

Type: Number
Default Value: 0

virtualModeEnabled

Specifies if the virtual mode is enabled.

Type: Boolean
Default Value: false

If the option is set to true, the widget initially loads only root items. Child items are loaded when their parent is being expanded.

NOTE
You can use the virtual mode only if the dataSource option holds the DataSource instance able to filter items by parent ID, and the dataStructure option is set to "plain". Otherwise, the virtualModeEnabled option is ignored.

Use this option to improve the widget performance when working with a huge data source.

visible

A Boolean value specifying whether or not the widget is visible.

Type: Boolean
Default Value: true

width

Specifies the width of the widget.

Return Value: Number|String

The widget width.

Default Value: undefined

The option can hold a value of the following types.

  • numeric
    The widget width in pixels.
  • string
    A CSS measurement of the widget width (e.g., "55px", "80%", "auto" and "inherit").
  • function
    The function returning the widget width. For example, see the following code.

    JavaScript
    width: function () { 
        return baseWidth - 10 + "%";
    }