Configuration

An object defining configuration options for the TreeView widget.

accessKey

Specifies the shortcut key that sets focus on the widget.

Type:

String

Default Value: null

The value of this option will be passed to the accesskey attribute of the HTML element that underlies the widget.

activeStateEnabled

Specifies 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

createChildren

Allows you to load nodes manually.

Type:

Function

Function parameters:
parentNode:

TreeView Node

The node that has been expanded; null for the root node.

Return Value:

Promise<any> (jQuery or native)

|

Array<Object>

A Promise that is resolved with the result from the server or an array of objects to be converted to child nodes.

If you have a large data source hosted remotely, loading all of it may take considerable time. To quicken the process, you can load data for an individual node using the createChildren function. This function will be called at the beginning of the widget's lifetime and each time a user expands a node whose child nodes have not been loaded yet.

jQuery
JavaScript
$(function() {
    $("#treeViewContainer").dxTreeView({
        createChildren: function (parentNode) {
            var d = $.Deferred();
            $.get("http://url/to/the/service", {
                    parentId: parentNode ? JSON.stringify(parentNode.key) : "0"
                })
                .done(function (result) {
                    d.resolve(result);
                });
            return d.promise();
        },
        dataStructure: "plain"
    });
});
Angular
HTML
TypeScript
<dx-tree-view
    [createChildren]="createChildren"
    dataStructure="plain">
</dx-tree-view>
import { ..., Inject } from "@angular/core";
import { HttpClient, HttpClientModule, HttpParams } from "@angular/common/http";
import "rxjs/add/operator/toPromise";
import { DxTreeViewModule } from "devextreme-angular";
// ...
export class AppComponent {
    constructor(@Inject(HttpClient) httpClient: HttpClient) { }
    createChildren = (parentNode) => {
        let params: HttpParams = new HttpParams()
            .set("parentId", parentNode ? JSON.stringify(parentNode.key) : "0");
        return httpClient.get("http://url/to/the/service", {
                params: params
            })
            .toPromise();
    }
}
@NgModule({
    imports: [
        // ...
        DxTreeViewModule,
        HttpClientModule 
    ],
    // ...
})
NOTE
The createChildren function applies only if the dataStructure option is set to "plain" and the dataSource option is unspecified.

View Demo

See Also

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
Data field names should not contain the following characters: ., ,, :, [, and ]. Their presence may cause issues in the widget's operation.
NOTE
The widget requires each data item to have a key field whose value is unique within the entire array.

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 Node Appearance topic.

See Also

dataStructure

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

Type:

String

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

If the option is set to "tree", the array should have a tree structure. This 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 }
];

View Demo

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.

View Demo

Use the TreeViewDataStructure enum to specify this option when the widget is used as an ASP.NET MVC Control. This enum accepts the following values: Plain and Tree.

See Also

disabled

Specifies whether the widget responds to user interaction.

Type:

Boolean

Default Value: false

disabledExpr

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

Type:

String

|

Function

Default Value: 'disabled'

displayExpr

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

Type:

String

|

Function

Default Value: 'text'

elementAttr

Specifies the attributes to be attached to the widget's root element.

Type:

Object

Default Value: {}
jQuery
$(function(){
    $("#treeViewContainer").dxTreeView({
        // ...
        elementAttr: {
            id: "elementId",
            class: "class-name"
        }
    });
});
Angular
HTML
TypeScript
<dx-tree-view ...
    [elementAttr]="{ id: 'elementId', class: 'class-name' }">
</dx-tree-view>
import { DxTreeViewModule } from "devextreme-angular";
// ...
export class AppComponent {
    // ...
}
@NgModule({
    imports: [
        // ...
        DxTreeViewModule
    ],
    // ...
})
ASP.NET MVC Control
Razor C#
Razor VB
@(Html.DevExtreme().TreeView()
    .ElementAttr("class", "class-name")
    // ===== or =====
    .ElementAttr(new {
        @id = "elementId",
        @class = "class-name"
    })
    // ===== or =====
    .ElementAttr(new Dictionary<string, object>() {
        { "id", "elementId" },
        { "class", "class-name" }
    })

)
@(Html.DevExtreme().TreeView() _
    .ElementAttr("class", "class-name")
    ' ===== or =====
    .ElementAttr(New With {
        .id = "elementId",
        .class = "class-name"
    })
    ' ===== or =====
    .ElementAttr(New Dictionary(Of String, Object) From {
        { "id", "elementId" },
        { "class", "class-name" }
    })
)

expandAllEnabled

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

Type:

Boolean

Default Value: false

expandedExpr

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

Type:

String

|

Function

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 the widget can be focused using keyboard navigation.

Type:

Boolean

Default Value: false, true (desktop)

hasItemsExpr

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

Type:

String

|

Function

Default Value: 'hasItems'

height

Specifies the widget's height.

Type:

Number

|

String

|

Function

Return Value:

Number

|

String

The widget's height.

Default Value: undefined

This option accepts a value of one of the following types:

  • Number
    The height in pixels.

  • String
    A CSS-accepted measurement of height. For example, "55px", "80%", "auto", "inherit".

  • Function
    A function returning either of the above. For example:

    JavaScript
    height: function() {
        return window.innerHeight / 1.5;
    }

hint

Specifies text for a hint that appears when a user pauses on the widget.

Type:

String

Default Value: undefined

hoverStateEnabled

Specifies whether the widget changes its state when a user pauses on it.

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.

Raised Events: optionChanged

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.

itemsExpr

Specifies which data field contains nested items. Applies only if the dataStructure option is "tree".

Type:

String

|

Function

Default Value: 'items'

itemTemplate

Specifies a custom template for items.

Type:

template

Function parameters:
itemData:

Object

The item object to be rendered.

itemIndex:

Number

The index of the item to be rendered.

itemElement:

Element (jQuery or HTML)

The container of the item to be rendered. It is an HTML Element or a jQuery Element when you use jQuery.

Return Value:

String

|

DOM Node

|

jQuery

A template name or container.

Default Value: 'item'

keyExpr

Specifies which data field provides keys for TreeView items.

Type:

String

|

Function

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

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 function that is executed when the widget's content is ready and each time the content is changed.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only when using Knockout.

Default Value: null

onDisposing

A function that is executed before the widget is disposed of.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only if you use Knockout.

Default Value: null

onInitialized

A function that is executed only once, after the widget is initialized.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

Default Value: null

You cannot access widget elements in this function because it is executed before they are ready. Use the onContentReady function instead.

onItemClick

A function that is executed when a collection item is clicked or tapped.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only if Knockout is used.

itemData:

Object

The clicked item's data.

itemElement:

Element (jQuery or HTML)

The item's container. It is an HTML Element or a jQuery Element when you use jQuery.

itemIndex:

Number

The clicked item's index.

The item's node.

event:

Event (jQuery or dxEvent)

The event that caused the handler execution. It is a dxEvent or a jQuery.Event when you use jQuery.

Default Value: null

onItemCollapsed

A function that is executed when a tree view item is collapsed.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only if Knockout is used.

itemData:

Object

The collapsed item's data.

itemElement:

Element (jQuery or HTML)

The item's container. It is an HTML Element or a jQuery Element when you use jQuery.

itemIndex:

Number

The item's index.

jQueryEvent:

jQuery.Event

The jQuery event that caused the handler execution. Deprecated in favor of the event field.

event:

Event (jQuery or dxEvent)

The event that caused the handler execution. It is a dxEvent or a jQuery.Event when you use jQuery.

The item's node.

Default Value: null

onItemContextMenu

A function that is executed when a collection item is right-clicked or pressed.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only if Knockout is used.

itemData:

Object

The item's data.

itemElement:

Element (jQuery or HTML)

The item's container. It is an HTML Element or a jQuery Element when you use jQuery.

itemIndex:

Number

The item's index.

jQueryEvent:

jQuery.Event

The jQuery event that caused the handler execution. Deprecated in favor of the event field.

The item's node.

Default Value: null

onItemExpanded

A function that is executed when a tree view item is expanded.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only if Knockout is used.

itemData:

Object

The expanded item's data.

itemElement:

Element (jQuery or HTML)

The item's container. It is an HTML Element or a jQuery Element when you use jQuery.

itemIndex:

Number

The item's index.

jQueryEvent:

jQuery.Event

The jQuery event that caused the handler execution. Deprecated in favor of the event field.

event:

Event (jQuery or dxEvent)

The event that caused the handler execution. It is a dxEvent or a jQuery.Event when you use jQuery.

The item's node.

Default Value: null

onItemHold

A function that is executed when a collection item has been held for a specified period.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only if Knockout is used.

itemData:

Object

The data of the item being held.

itemElement:

Element (jQuery or HTML)

The item's container. It is an HTML Element or a jQuery Element when you use jQuery.

itemIndex:

Number

The item's index.

event:

Event (jQuery or dxEvent)

The event that caused the handler execution. It is a dxEvent or a jQuery.Event when you use jQuery.

The item's node.

Default Value: null

onItemRendered

A function that is executed after a collection item is rendered.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only if Knockout is used.

itemData:

Object

The current item's data.

itemElement:

Element (jQuery or HTML)

The item's container. It is an HTML Element or a jQuery Element when you use jQuery.

itemIndex:

Number

The current item's index.

The item's node.

Default Value: null

onItemSelectionChanged

A function that is executed when a tree view item is selected or the selection is canceled.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only if Knockout is used.

The selected item's node.

itemElement:

Element (jQuery or HTML)

The selected item's container.

Default Value: null

This function is executed under one of the following conditions:

View Demo

See Also

onOptionChanged

A function that is executed after a widget option is changed.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

name:

String

The option's short name.

fullName:

String

The option's full name.

value: any

The option's new value.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only if you use Knockout.

Default Value: null

onSelectAllValueChanged

A function that is executed when the "Select All" check box value is changed. Applies only if showCheckBoxesMode is "selectAll" and selectionMode is "multiple".

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only if Knockout is used.

value:

Boolean

The "Select All" check box's new state.

Default Value: null

onSelectionChanged

A function that is executed when a tree view item is selected or the selection is canceled.

Type:

Function

Function parameters:
e:

Object

Information about the event.

Object structure:
component:

TreeView

The widget's instance.

element:

Element (jQuery or HTML)

The widget's container. It is an HTML Element or a jQuery Element when you use jQuery.

model:

Object

The model data. Available only if Knockout is used.

Default Value: null

This function is executed under one of the following conditions:

parentIdExpr

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

Type:

String

|

Function

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

Switches the widget to a right-to-left representation.

Type:

Boolean

Default Value: false

When this option is set to true, the widget text flows from right to left, and the layout of elements is reversed. To switch the entire application/site to the right-to-left representation, assign true to the rtlEnabled field of the object passed to the DevExpress.config(config) method.

JavaScript
DevExpress.config({
    rtlEnabled: true
});
See Also

scrollDirection

A string value specifying available scrolling directions.

Type:

String

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

Use the ScrollDirection enum to specify this option when the widget is used as an ASP.NET MVC Control. This enum accepts the following values: Vertical, Horizontal, and Both.

searchEditorOptions

Configures the search panel.

Default Value: {}

See the TextBox Configuration for options you can specify in this object.

NOTE
The fields of a configuration object passed to this option do not support two-way binding in Angular, AngularJS, and Knockout and event bindings in Angular.

searchEnabled

Specifies whether the search panel is visible.

Type:

Boolean

Default Value: false

searchExpr

Specifies a data object's field name or an expression whose value is compared to the search string.

Type:

getter

|

Array<getter>

Default Value: null

If you need to search several fields, assign an array of field names to this option.

searchExpr: ["firstName", "lastName"]

searchMode

Specifies a comparison operation used to search widget items.

Type:

String

Default Value: 'contains'
Accepted Values: 'contains' | 'startswith' | 'equals'

Use the CollectionSearchMode enum to specify this option when the widget is used as an ASP.NET MVC Control. This enum accepts the following values: Contains, StartsWith, and Equals.

searchTimeout

Specifies a delay in milliseconds between when a user finishes typing, and the search is executed.

Type:

Number

Default Value: undefined

searchValue

Specifies the current search string.

Type:

String

Default Value: ''
NOTE
When the virtual mode is enabled, the TreeView searches only the loaded items.
See Also

selectAllText

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

Type:

String

Default Value: 'Select All'

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.

Type:

String

|

Function

Default Value: 'selected'

selectionMode

Specifies item selection mode.

Type:

String

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

Use the NavSelectionMode enum to specify this option when the widget is used as an ASP.NET MVC Control. This enum accepts the following values: Single and 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.

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.

Use the TreeViewCheckBoxMode enum to specify this option when the widget is used as an ASP.NET MVC Control. This enum accepts the following values: None, Normal, and SelectAll.

View Demo

See Also

tabIndex

Specifies the number of the element when the Tab key is used for navigating.

Type:

Number

Default Value: 0

The value of this option will be passed to the tabindex attribute of the HTML element that underlies the widget.

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.

View Demo

See Also

visible

Specifies whether the widget is visible.

Type:

Boolean

Default Value: true

width

Specifies the widget's width.

Type:

Number

|

String

|

Function

Return Value:

Number

|

String

The widget's width.

Default Value: undefined

This option accepts a value of one of the following types:

  • Number
    The width in pixels.

  • String
    A CSS-accepted measurement of width. For example, "55px", "80%", "auto", "inherit".

  • Function
    A function returning either of the above. For example:

    JavaScript
    width: function() {
        return window.innerWidth / 1.5;
    }