Blazor AutoComplete Overview

The Blazor AutoComplete component is a textbox that offers the users hints as they type. These suggestions can be filtered as the user types. The user can write their own value or click a suggestion from the dropdown to select it and populate the input. You can control the list of suggestions through data binding, various appearance settings like dimensions and templates.

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Creating AutoComplete

  1. Use the TelerikAutoComplete tag to add the component to your razor page.

  2. Populate the Data property with the collection of items that you want to appear in the dropdown.

  3. Bind the value of the component to the same type as the member of the ValueField parameter.

  4. (Optional) Enable features like placeholder text and clear button.

AutoComplete with two-way value binding and data binding to a primitive type

@* AutoComplete with two-way value binding and data binding to a primitive type *@

User input: @TheValue
<br />
<TelerikAutoComplete Data="@Suggestions" @bind-Value="@TheValue"
    Placeholder="Enter your role (can be free text)" ClearButton="true" />

@code{
    //Current value is null (no item is selected) which allows the Placeholder to be displayed.
    string TheValue { get; set; }

    List<string> Suggestions { get; set; } = new List<string> {
        "Manager", "Developer", "QA", "Technical Writer", "Support Engineer", "Sales Agent", "Architect", "Designer"
    };
}

If you want to get a value identifier for the items in the dropdown instead of their text, consider the ComboBox component. The AutoComplete is a free text input that accepts any text the user writes, not just the suggestions from the dropdown. Thus, the Value of the AutoComplete is always a string, while the ComboBox can provide you with a number or a Guid, not only a string.

Component Reference

The AutoComplete is a generic component and its type is determined by the type of the model you use as its data source. You can find examples in the Data Bind - Considerations article.

Data Binding

The Blazor AutoComplete requires a data source so that it can populate the dropdown with data. To provide a data source, use the Data property. Read more about the Blazor AutoComplete data binding...

Filtering

The Blazor AutoComplete has a built-in filter that narrows down the shown suggestions as the end-user types. To configure this feature, use the Filterable parameter. Additionally, you can choose between different filter operators and configure after how many symbols the list with suggestions will appear. Read more about the Blazor AutoComplete filter...

Grouping

The Blazor AutoComplete enables you to group the listed suggestions into categories so you can help the end-user to browse faster through longer lists. Read more about the Blazor AutoComplete grouping...

Templates

You can use the functionality of the built-in templates and customize the default rendering of the component. Read more about the Blazor AutoComplete templates...

Validation

You can ensure that the component value is acceptable by using the built-in validation. Read more about input validation....

Virtualization

By virtualizing the elements in the dropdown, you can use huge data sources without performance issues. The UI virtualization works with both local and remote data. Read more about the Blazor AutoComplete virtualization...

Parameters

The Blazor AutoComplete provides various parameters that allow you to configure the component:

Parameter Type Description
Data IEnumerable<TItem> allows you to provide the data source. Required.
DebounceDelay int
150
Time in milliseconds between the last typed symbol and the internal oninput event firing. Applies when the user types and filters. Use it to balance between client-side performance and number of database queries.
Enabled bool Whether the component is enabled.
Filterable bool Whether filtering is enabled for the end user (suggestions will get narrowed down as they type).
FilterOperator StringFilterOperator
(StartsWith)
The string operation that will be used for filtering.
Id string Renders as the id attribute on the <input /> element, so you can attach a <label for=""> to the input.
TItem Type The type of the model to which the component is bound. Required if you can't provide Data or Value. Determines the type of the reference object.
Value and bind-Value string Get/set the value of the component, can be used for binding. Use the @bind-Value syntax for two-way binding, for example, to a variable of your own. The Value must be a string.
ValueField string
(Value)
The name of the field from the model that will be shown as hints to the user. Not required when binding to a simple list of strings.
TabIndex int? Maps to the tabindex attribute of the HTML element. You can use it to customize the order in which the inputs in your form focus with the Tab key.
ClearButton bool Whether the user will have the option to clear the selected value with a button on the input. When it is clicked, the Value will be updated to string.Empty.
Enabled bool Use this Boolean property to render a disabled Blazor AutoComplete component until certain requirements are met.
MinLength int How many characters the text has to be before the suggestions list appears. Cannot be 0. Often works together with filtering.
Placeholder string The text the user sees as a hint when there is no text in the input. In order for it to be shown, the Value parameter should be set to the default value for string (null).

Styling and Appearance

The following parameters enable you to customize the appearance of the Blazor AutoComplete:

Parameter Type Description
Width string the width of the component. It will target both the dropdown and the main element if the dropdown has no specific width set. The default Width value is null, but the theme applies 100%. Use the Width property or custom CSS to set another value in any supported unit.
Class string the CSS class that will be rendered on the main wrapping element of the component.

You can find more options for customizing the AutoComplete styling in the Appearance article.

The popup of the component can be additionally customized via nested tags:

<TelerikAutoComplete>
    <AutoCompleteSettings>
        <AutoCompletePopupSettings Height="..." />
    </AutoCompleteSettings>
</TelerikAutoComplete>

The AutoComplete provides the following popup settings:

Parameter Type Description
Class string additional CSS class to customize the appearance of the dropdown.
Height string the height of the expanded dropdown list element.
Width string the width of the expanded dropdown list element. If you don't specify a value, the dropdown width will match the main element which can help with responsive layouts and 100% widths.

If you are looking for more fields from the view-model that describes the dropdown items, not just the Value, see the Get model from dropdown KB article and the OnChange event.

You may also want to review/join the discussion and Vote for this request: Binding DropDownList Value to complex model

Next Steps

See Also

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