Filter Events

This article explains the available events for the Telerik Filter for Blazor:

• OnUpdate
• ValueChanged

OnUpdate

The OnUpdate event fires when the user changes the Filter Value. The component is designed for one-way binding and works directly with the object reference of the bound CompositeFilterDescriptor. The component updates the Value internally. Use the OnUpdate event to handle any additional logic when the Filter Value is modified.

Handle OnUpdate

@using Telerik.DataSource

<div class="info-note">Change any filter value to trigger the event and see the message update from the OnUpdate handler.</div>

<TelerikFilter Value="@Value" OnUpdate="@OnFilterUpdate">
    <FilterFields>
        <FilterField Name="@(nameof(Person.EmployeeId))" Type="@(typeof(int))" Label="Id"></FilterField>
        <FilterField Name="@(nameof(Person.Name))" Type="@(typeof(string))" Label="First Name"></FilterField>
        <FilterField Name="@(nameof(Person.AgeInYears))" Type="@(typeof(int))" Label="Age"></FilterField>
    </FilterFields>
</TelerikFilter>
<br />
<div>
    <strong>@EventMessage</strong>
</div>

<style>
    .info-note {
        background: #e6f4ff;
        padding: 10px;
        border-radius: 4px;
        margin-bottom: 10px;
        width: 400px;
    }
</style>

@code {
    private CompositeFilterDescriptor Value { get; set; } = new CompositeFilterDescriptor();
    private string EventMessage { get; set; } = string.Empty;

    private void OnFilterUpdate()
    {
        EventMessage = $"Filter updated at {DateTime.Now:HH:mm:ss}";
    }

    public class Person
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; } = string.Empty;
        public int AgeInYears { get; set; }
    }
}

ValueChanged

The ValueChanged event fires when the value has changed. Its event handler receives the updated CompositeFilterDescriptor as an argument.

The ValueChanged event is deprecated and will be removed in future versions. Use the OnUpdate event instead.

Handle ValueChanged

@* This code snippet showcases an example of how to handle the ValueChanged event. *@

@using Telerik.DataSource

<TelerikFilter Value="@Value" ValueChanged="@OnValueChanged">
    <FilterFields>
        <FilterField Name="@(nameof(Person.EmployeeId))" Type="@(typeof(int))" Label="Id"></FilterField>
        <FilterField Name="@(nameof(Person.Name))" Type="@(typeof(string))" Label="First Name"></FilterField>
        <FilterField Name="@(nameof(Person.AgeInYears))" Type="@(typeof(int))" Label="Age"></FilterField>
        <FilterField Name="@(nameof(Person.IsOutOfOffice))" Type="@(typeof(bool))" Label="Out Of Office"></FilterField>
        <FilterField Name="@(nameof(Person.HireDate))" Type="@(typeof(DateTime))" Label="Hire Date"></FilterField>
    </FilterFields>
</TelerikFilter>

<div>
    <strong>ValueChanged triggered count: </strong> @TriggeredValueChangedCount

    <div class="log-container">
        List of applied filters:
        @compositeFilterDescriptorFragment(Value)
    </div>
</div>

@code {
    public CompositeFilterDescriptor Value { get; set; } = new CompositeFilterDescriptor();
    public int TriggeredValueChangedCount { get; set; }

    private void OnValueChanged(CompositeFilterDescriptor filter)
    {
        Value = filter;
        TriggeredValueChangedCount++;
    }

    static RenderFragment<CompositeFilterDescriptor> compositeFilterDescriptorFragment = (cfd) =>
        @<text>
            @{
                <div>CompositeFilterDescriptor info: Logical Operator: @cfd.LogicalOperator</div>

                FilterDescriptor currentFilterDescriptor;
                CompositeFilterDescriptor currentCompositeDescriptor;

                @foreach (var item in cfd.FilterDescriptors)
                {
                    if (item is CompositeFilterDescriptor)
                    {
                        currentCompositeDescriptor = item as CompositeFilterDescriptor;
                        @compositeFilterDescriptorFragment(currentCompositeDescriptor);
                    }
                    else
                    {
                        currentFilterDescriptor = item as FilterDescriptor;
                        @filterDescriptorFragment(currentFilterDescriptor)
                    }
                }
            }
        </text>;

    static RenderFragment<FilterDescriptor> filterDescriptorFragment = (fd)
        => @<text><div>FilterDescriptor info: Member: @fd.Member Type: @fd.MemberType Value: @fd.Value</div></text>;
        public class Person
    {
        public int EmployeeId { get; set; }

        public string Name { get; set; }

        public int AgeInYears { get; set; }

        public bool IsOutOfOffice { get; set; }

        public DateTime HireDate { get; set; }
    }
}

<style>
    .log-container div {
        clear: both;
    }
</style>

See Also

• Live Demo: Filter