Events

This article explains the events available in the Telerik DateInput for Blazor:

• OnBlur
• OnChange
• ValueChanged

OnBlur

The OnBlur event fires when the component loses focus.

Handle the OnBlur event

@* You do not have to use OnChange to react to loss of focus *@

@result

<TelerikDateInput @bind-Value="@DateInputValue"
                  OnBlur="@OnBlurHandler">
</TelerikDateInput>

@code{
    private string result = string.Empty;

    private DateTime? DateInputValue { get; set; } = DateTime.Now;

    private void OnBlurHandler()
    {
        result = string.Format("BLUR fired, current value is {0:dd/MMM/yyyy}.", DateInputValue);
    }
}

The event is an EventCallback. It can be synchronous and return void, or asynchronous and return async Task. Do not use async void.

OnChange

The OnChange event represents a user action that confirms the current value. It fires when the user presses Enter in the input or when the input loses focus.

The event handler receives an object argument that you need to cast to the actual Value type. The argument can hold a value or be null, depending on the user input and the Value type.

The DateInput is a generic component, so you must either provide a Value, or a type to the T parameter of the component.

Handle OnChange and use two-way binding

@result
<br />
model value: @DateInputValue
<br />

<TelerikDateInput @bind-Value="@DateInputValue" 
                  OnChange="@MyOnChangeHandler">
</TelerikDateInput>

@code {
    private string result = string.Empty;

    private DateTime? DateInputValue { get; set; } = DateTime.Now;

    private void MyOnChangeHandler(object userInput)
    {
        // if you do not provide a Value, you must provide the Type parameter to the component
        result = string.Format("The user entered: {0:dd/MMM/yyyy}", (DateTime)userInput);
    }
}

The event is an EventCallback. It can be synchronous and return void, or asynchronous and return async Task. Do not use async void.

The OnChange event is a custom event and does not interfere with bindings, so you can use it together with models and forms.

ValueChanged

The ValueChanged event fires:

• During typing when the resulting input value is valid.
• On input blur if the input value is not valid and the Value type is nullable.

Handle ValueChanged and provide initial value

@result
<br />
model value: @DateInputValue
<br />

<TelerikDateInput Value="@DateInputValue" 
                  ValueChanged="@( (DateTime d) => MyValueChangeHandler(d) )">
</TelerikDateInput>

@code {
    private string result = string.Empty;

    private DateTime DateInputValue { get; set; } = DateTime.Now;

    private void MyValueChangeHandler(DateTime userInput)
    {
        result = string.Format("The user entered: {0:dd/MMM/yyyy}", userInput);

        //you have to update the model manually because handling the ValueChanged event does not let you use @bind-Value
        DateInputValue = userInput;
    }
}

The event is an EventCallback. It can be synchronous and return void, or asynchronous and return async Task. Do not use async void.

The lambda expression in the handler is required by the framework: https://github.com/aspnet/AspNetCore/issues/12226.

See Also

• ValueChanged and Validation
• Fire OnChange Only Once