Class ComboBoxEvents<TValue, TItem>

Defines event handlers for the SfComboBox<TValue, TItem> component in the Blazor framework.

Inheritance

System.Object

ComboBoxEvents<TValue, TItem>

Namespace: Syncfusion.Blazor.DropDowns

Assembly: Syncfusion.Blazor.dll

Syntax

public class ComboBoxEvents<TValue, TItem> : OwningComponentBase

Type Parameters

Name	Description
TValue	The type of the value associated with the ComboBox.
TItem	The type of items associated with the ComboBox.

Remarks

This class provides event callbacks for various interactions with the ComboBox, such as data fetching, selection, and popup events.

Examples

<SfComboBox TValue="string" TItem="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" Created="@OnCreated" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Apple", "Banana", "Orange" };
    private void OnCreated(object args)
    {
        // Handle component creation
    }
}

Constructors

ComboBoxEvents()

Declaration

public ComboBoxEvents()

Properties

Blur

Gets or sets the event callback invoked when the ComboBox loses focus.

Declaration

public EventCallback<object> Blur { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<System.Object>	An Microsoft.AspNetCore.Components.EventCallback<> that receives an System.Object when triggered.

Remarks

This event is triggered when the ComboBox loses focus, enabling developers to perform actions such as validation or UI updates in response to the blur event.

Examples

<SfComboBox TItem="string" TValue="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" Blur="@OnBlurHandler" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Small", "Medium", "Large" };
    public void OnBlurHandler(object args)
    {
        // Handle blur event
    }
}

Closed

Gets or sets the event callback invoked after the dropdown popup is closed.

Declaration

public EventCallback<ClosedEventArgs> Closed { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<ClosedEventArgs>	An Microsoft.AspNetCore.Components.EventCallback<> that receives a ClosedEventArgs object when triggered.

Remarks

This event is triggered after the dropdown popup is closed, allowing developers to perform post-closure actions such as updating the UI or processing the selected value.

Examples

<SfComboBox TValue="string" TItem="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" Closed="@OnClosed" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Apple", "Banana", "Orange" };
    private void OnClosed(ClosedEventArgs args)
    {
        // Handle popup closed event
    }
}

Created

Gets or sets the event callback invoked when the ComboBox component is created.

Declaration

public EventCallback<object> Created { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<System.Object>	An Microsoft.AspNetCore.Components.EventCallback<> that receives an System.Object when triggered.

Remarks

This event is triggered after the ComboBox is initialized and rendered, allowing developers to perform setup or initialization tasks.

Examples

<SfComboBox TItem="string" TValue="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" Created="@OnCreated" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Small", "Medium", "Large" };
    public void OnCreated(object args)
    {
        // Handle component creation
    }
}

CustomValueSpecifier

Gets or sets the event callback invoked when a custom value not present in the data source is entered.

Declaration

public EventCallback<CustomValueSpecifierEventArgs<TItem>> CustomValueSpecifier { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<CustomValueSpecifierEventArgs<TItem>>	An Microsoft.AspNetCore.Components.EventCallback<> that receives a CustomValueSpecifierEventArgs<T> object when triggered.

Remarks

This event is triggered when a user enters a value not present in the data source and AllowCustom is enabled. Developers can use this event to define the custom item to be added to the ComboBox.

Examples

<SfComboBox TValue="int" TItem="Countries" DataSource="@CountryList">
    <ComboBoxEvents TValue="int" TItem="Countries" CustomValueSpecifier="@CustomValue" />
    <ComboBoxFieldSettings Text="Name" Value="Code" />
</SfComboBox>
@code {
    public class Countries
    {
        public string Name { get; set; }
        public int Code { get; set; }
    }
    private List<Countries> CountryList = new List<Countries>
    {
        new Countries { Code = 101, Name = "Australia" },
        new Countries { Code = 102, Name = "Canada" }
    };
    private void CustomValue(CustomValueSpecifierEventArgs<Countries> args)
    {
        args.Item = new Countries { Code = 103, Name = args.Text };
    }
}

DataBound

Gets or sets the event callback invoked when the data source is populated in the popup list.

Declaration

public EventCallback<DataBoundEventArgs> DataBound { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<DataBoundEventArgs>	An Microsoft.AspNetCore.Components.EventCallback<> that receives a DataBoundEventArgs object when triggered.

Remarks

This event is triggered after the data source is populated in the ComboBox popup, providing access to the loaded items for further processing.

Examples

<SfComboBox TItem="string" TValue="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" DataBound="@OnDataBound" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Small", "Medium", "Large" };
    public void OnDataBound(DataBoundEventArgs args)
    {
        // Process populated data
    }
}

Destroyed

Gets or sets the event callback invoked when the ComboBox is disposed.

Declaration

public EventCallback<object> Destroyed { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<System.Object>	An Microsoft.AspNetCore.Components.EventCallback<> that receives an System.Object when triggered.

Remarks

This event is triggered when the ComboBox is disposed, allowing cleanup or finalization tasks to be performed.

Examples

<SfComboBox TItem="string" TValue="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" Destroyed="@OnDestroyed" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Small", "Medium", "Large" };
    public void OnDestroyed(object args)
    {
        // Handle component destruction
    }
}

Filtering

Gets or sets the event callback invoked when filtering is performed on the ComboBox data source.

Declaration

public EventCallback<FilteringEventArgs> Filtering { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<FilteringEventArgs>	An Microsoft.AspNetCore.Components.EventCallback<> that receives a FilteringEventArgs object when triggered.

Remarks

This event is triggered when the user types in the ComboBox and filtering is enabled via the AllowFiltering property. It allows developers to customize the filtering logic or cancel the default filtering action using Cancel or PreventDefaultAction.

Examples

<SfComboBox TValue="string" TItem="string" AllowFiltering="true" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" Filtering="@OnFiltering" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Apple", "Banana", "Orange" };
    private void OnFiltering(FilteringEventArgs args)
    {
        // Customize filtering logic
        args.PreventDefaultAction = true;
    }
}

Focus

Gets or sets the event callback invoked when the ComboBox gains focus.

Declaration

public EventCallback<object> Focus { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<System.Object>	An Microsoft.AspNetCore.Components.EventCallback<> that receives an System.Object when triggered.

Remarks

This event is triggered when the ComboBox input gains focus, allowing developers to perform actions such as UI updates or input preparation.

Examples

<SfComboBox TValue="string" TItem="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" Focus="@OnFocus" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Apple", "Banana", "Orange" };
    private void OnFocus(object args)
    {
        // Handle focus event
    }
}

OnActionBegin

Gets or sets the event callback invoked before fetching data from the data source.

Declaration

public EventCallback<ActionBeginEventArgs> OnActionBegin { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<ActionBeginEventArgs>	An Microsoft.AspNetCore.Components.EventCallback<> that receives an ActionBeginEventArgs object when triggered.

Remarks

This event is fired before the ComboBox fetches data, allowing developers to modify the query or cancel the action via Cancel.

Examples

<SfComboBox TValue="string" TItem="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" OnActionBegin="@OnActionBeginHandler" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Apple", "Banana", "Orange" };
    private void OnActionBeginHandler(ActionBeginEventArgs args)
    {
        // Modify query or cancel action
    }
}

OnActionComplete

Gets or sets the event callback invoked after data is successfully fetched from the data source.

Declaration

public EventCallback<ActionCompleteEventArgs<TItem>> OnActionComplete { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<ActionCompleteEventArgs<TItem>>	An Microsoft.AspNetCore.Components.EventCallback<> that receives an ActionCompleteEventArgs<TItem> object when triggered.

Remarks

This event is triggered after data is fetched, providing access to the fetched data and query via Result and Query. It allows cancellation of further processing via Cancel.

Examples

<SfComboBox TValue="string" TItem="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" OnActionComplete="@OnActionCompleteHandler" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Apple", "Banana", "Orange" };
    private void OnActionCompleteHandler(ActionCompleteEventArgs<string> args)
    {
        // Process fetched data
    }
}

OnActionFailure

Gets or sets the event callback invoked when the data fetch request fails.

Declaration

public EventCallback<Exception> OnActionFailure { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<System.Exception>	An Microsoft.AspNetCore.Components.EventCallback<> that receives an System.Exception object when triggered.

Remarks

This event is triggered when a data fetch request fails, providing the exception details for error handling.

Examples

<SfComboBox TValue="string" TItem="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" OnActionFailure="@OnActionFailureHandler" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Apple", "Banana", "Orange" };
    private void OnActionFailureHandler(Exception ex)
    {
        // Handle fetch failure
    }
}

OnClose

Gets or sets the event callback invoked before the dropdown popup closes.

Declaration

public EventCallback<PopupEventArgs> OnClose { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<PopupEventArgs>	An Microsoft.AspNetCore.Components.EventCallback<> that receives a PopupEventArgs object when triggered.

Remarks

This event is triggered before the dropdown popup closes, allowing cancellation of the close action via Cancel. If cancelled, the popup remains open, enabling developers to enforce specific conditions for closing.

Examples

<SfComboBox TItem="string" TValue="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" OnClose="@OnCloseHandler" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Small", "Medium", "Large" };
    public void OnCloseHandler(PopupEventArgs args)
    {
        args.Cancel = true;
    }
}

OnOpen

Gets or sets the event callback invoked before the dropdown popup opens.

Declaration

public EventCallback<BeforeOpenEventArgs> OnOpen { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<BeforeOpenEventArgs>	An Microsoft.AspNetCore.Components.EventCallback<> that receives a BeforeOpenEventArgs object when triggered.

Remarks

This event is triggered before the dropdown popup opens, allowing cancellation of the open action via Cancel. It enables developers to perform pre-open logic or prevent the popup from opening.

Examples

<SfComboBox TItem="string" TValue="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" OnOpen="@OnOpenHandler" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Small", "Medium", "Large" };
    public void OnOpenHandler(BeforeOpenEventArgs args)
    {
        args.Cancel = true;
    }
}

OnValueSelect

Gets or sets the event callback invoked when an item is selected from the dropdown popup.

Declaration

public EventCallback<SelectEventArgs<TItem>> OnValueSelect { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<SelectEventArgs<TItem>>	An Microsoft.AspNetCore.Components.EventCallback<> that receives a SelectEventArgs<T> object when triggered.

Remarks

This event is triggered when an item is selected from the dropdown, providing details about the selected item via ItemData. It allows cancellation of the selection via Cancel.

Examples

<SfComboBox TValue="string" TItem="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" OnValueSelect="@OnValueSelect" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Apple", "Banana", "Orange" };
    private void OnValueSelect(SelectEventArgs<string> args)
    {
        // Handle item selection
    }
}

Opened

Gets or sets the event callback invoked after the dropdown popup is opened.

Declaration

public EventCallback<PopupEventArgs> Opened { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<PopupEventArgs>	An Microsoft.AspNetCore.Components.EventCallback<> that receives a PopupEventArgs object when triggered.

Remarks

This event is triggered after the dropdown popup is opened, providing access to popup properties via Popup for further customization or interaction.

Examples

<SfComboBox TValue="string" TItem="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" Opened="@OnOpened" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Apple", "Banana", "Orange" };
    private void OnOpened(PopupEventArgs args)
    {
        // Handle popup opened event
    }
}

ValueChange

Gets or sets the event callback invoked when the Value property changes.

Declaration

public EventCallback<ChangeEventArgs<TValue, TItem>> ValueChange { get; set; }

Property Value

Type	Description
Microsoft.AspNetCore.Components.EventCallback<ChangeEventArgs<TValue, TItem>>	An Microsoft.AspNetCore.Components.EventCallback<> that receives a ChangeEventArgs<TValue, TItem> object when triggered.

Remarks

This event is triggered when an item is selected from the popup or when the user changes the model value, either by typing a custom value (if AllowCustom is enabled) or selecting an existing item. It provides access to the new and previous values for further processing.

Examples

<SfComboBox TItem="string" TValue="string" DataSource="@MyList">
    <ComboBoxEvents TValue="string" TItem="string" ValueChange="@OnChange" />
</SfComboBox>
@code {
    protected List<string> MyList = new List<string> { "Small", "Medium", "Large" };
    public void OnChange(ChangeEventArgs<string, string> args)
    {
        var NewValue = args.Value;
    }
}

Methods

ComponentDispose(Boolean)

Declaration

protected void ComponentDispose(bool disposing)

Parameters

Type	Name	Description
System.Boolean	disposing