See Also

• SelectBox - Create a User-Defined Item
• TagBox - Create a User-Defined Item

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

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

This option accepts one of the following:

• Array
  A JavaScript array that contains string, numeric, Boolean values, or plain objects.

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

• DataSource or its configuration object
  The DataSource is an object that provides an API for data processing. The DataSource's underlying data access logic is isolated in a store. Refer to the Data Layer and DataSource Examples guides for more information about the DataSource.

If the data source contains objects, specify the key in the store and/or a data field providing values in the widget.

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.

See Also

• key in ArrayStore | CustomStore | LocalStore | ODataStore

If the data source item is a simple object holding a value (string, numeric, Boolean, etc.), assign 'this' to the displayExpr option. If the item is a plain object item, assign the required field name or path to the option.

The value you pass to this option does not affect widget behavior. Pass an observable variable to this option to get the value currently displayed by the widget.

See Also

• SelectBox - Customize Drop-Down Button Demo
• Custom Templates

You can configure this option in an ASP.NET MVC Control as follows:

@(Html.DevExtreme().WidgetName()
    .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().WidgetName() _
    .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" }
    })
)

See Also

• Customize Item Appearance
• Custom Templates

When this option is true, make sure that all data source objects have the following structure:

var dataSource = [{
    key: "Group 1", // Group caption 
    items: [ // Items in the group
        { ... },
        { ... }
    ]
}, {
    // ...
}];

You can supply data to this structure using the DataSource object's group option.

See Also

• SelectBox - Grouped Items Demo
• TagBox - Grouped Items Demo
• SelectBox - Grouping
• TagBox - Grouping

View Demo

See Also

• Customize Group Headers
• Custom Templates

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;
  }

You can configure this option in an ASP.NET MVC Control as follows:

@(Html.DevExtreme().WidgetName()
    .InputAttr("id", "inputId")
    // ===== or =====
    .InputAttr(new {
        @id = "inputId"
    })
    // ===== or =====
    .InputAttr(new Dictionary<string, object>() {
        { "id", "inputId" }
    })
)

@(Html.DevExtreme().WidgetName() _
    .InputAttr("id", "inputId")
    ' ===== or =====
    .InputAttr(New With {
        .id = "inputId"
    })
    ' ===== or =====
    .InputAttr(New Dictionary(Of String, Object) From {
        { "id", "inputId" }
    })
)

In Knockout apps, you may need to inform a user about an error that occurred during the validation of a view model field. For this purpose, set the editor's isValid option to the isValid value of the dxValidator that validates this field. To show an error message, set the editor's validationError option to the dxValidator's validationError value.

var editorValue = ko.observable("").extend({
    dxValidator: {
        validationRules: [{
            type: 'required',
            message: 'Specify this value'
        }]
    }
});
var viewModel = {
    editorOptions: {
        value: editorValue,
        isValid: editorValue.dxValidator.isValid,
        validationError: editorValue.dxValidator.validationError
    }
};

The editor's isValid and validationError options should also be specified when using a custom validation engine. In this instance, the validation result will be displayed for the editor by the means of the DevExtreme Validation UI.

See Also

• Knockout Only - Validate a View Model
• Use a Custom Validation Engine

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.

See Also

• Customize Item Appearance
• Custom Templates

If the number of entered characters reaches the value assigned to this option, the widget does not allow you to enter any more characters.

Specify this option if the widget lies within an HTML form that will be submitted.

If you configure the widget as an ASP.NET MVC Control, use this option to bind the widget to a model property. If this model property contains Data Annotation validation attributes, you get the client-side validation enabled by default.

Assign a function to perform a custom action when a change within the widget's input element is committed by an end user.

Assign a function to perform a custom action after a drop-down editor has been hidden.

If data displayed by the widget is specified using a DataSource instance, the contentReady event fires each time the load() method of the DataSource instance is called as well as when widget content is ready. In this case, when you create the widget, the contentReady event is raised twice: when the widget's content is ready (at this moment, the widget does not display items) and when the DataSource is loaded (the widget displays the loaded items).

Assign a function to perform a custom action after the widget's input is copied.

See Also

• SelectBox - Create a User-Defined Item
• TagBox - Create a User-Defined Item

Assign a function to perform a custom action after the widget's input is cut.

Assign a function to perform a custom action after the 'Enter' key is pressed within the widget's input element.

Assign a function to perform a custom action after the widget's input is focused.

Assign a function to perform a custom action after the widget's input element loses focus.

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

Assign a function to perform a custom action when a value within the widget's input element is changed by an end user.

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 directly to this option.

Assign a function to perform a custom action when a key is pressed down within the widget's input element.

Assign a function to perform a custom action when the keypress DOM event is raised for the current input element.

Assign a function to perform a custom action when a key is released within the widget's input element.

Assign a function to perform a custom action when the drop-down editor is shown.

Assign a function to perform a custom action after the widget's input is pasted.

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

Assign a function to perform a custom action when the editor value changes.

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.

DevExpress.config({
    rtlEnabled: true
});

See Also

• Right-to-Left Support Demo: DataGrid | Navigation Widgets | Editors

See Also

• Configure Search Parameters

In most cases, you should pass the name of a field by whose value data items are searched. If you need to search elements by several field values, assign an array of field names to this option.

searchExpr: ["firstName", "lastName"]

For more information on searching, refer to the Search API section of the Data Layer article. For information on getters, refer to the Getters and Setters section of the Data Layer article.

When using the widget as an ASP.NET MVC Control, specify this option using the DropDownSearchMode enum. This enum accepts the following values: Contains and StartsWith.

The Clear button sets the widget value to null.

If this option is disabled, the widget does not display values until the number of typed characters exceeds the minSearchLength value, otherwise it displays all values regardless of the specified filtering condition.

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

See Also

• Use a Custom Validation Engine

The following option values are possible:

• auto
  The tooltip with the message is displayed when the editor is in focus.
• always
  The tooltip with the message is not hidden when the editor loses focus.

When using the widget as an ASP.NET MVC Control, specify this option using the ValidationMessageMode enum. This enum accepts the following values: Auto and Always.

This option accepts a single event name or several names separated by spaces.

The recommended events are "keyup", "blur", "change", and "focusout", but you can use other events as well.

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;
  }