Update Data in Data-Bound Components

• Apr 18, 2023
• 3 minutes to read

Data-bound components, such as Grid, Chart, ComboBox, Context Menu, List Box, Menu, TagBox, and TreeView, automatically update values of their Data properties if a component uses a collection that implements the INotifyCollectionChanged or IBindingList interface as a data source. In this case, the collection notifies the component about data changes.

If a component uses a data source of another type (for example, List<T>), Data properties are not updated automatically.

Update an Editor Data Source

The following code snippet shows how to use an ObservableCollection<T> or BindingList<T> object as a data source for the List Box component.

@using System.ComponentModel
@using System.Collections.ObjectModel 

<DxButton Text="Add something"
          Click="(e) => UpdateDataSource()" />

<DxListBox Data="@DataSource"
           @bind-Values="@Values" />

@code {
    // Declare a data source variable
    BindingList<string> DataSource = new BindingList<string>();
    // OR
    // ObservableCollection<string> DataSource = new ObservableCollection<string>();

    IEnumerable<string> Values { get; set; }
    int ItemNumber { get; set; } = 0; 

    void UpdateDataSource()
    {
        ItemNumber++;
        DataSource.Add("Item" + ItemNumber.ToString());
    }
}

Update a Grid Data Source

For more information and an example, refer to the following help topic: Observable Data Collections.

Update a Chart Data Source

The following example adds a new value to the WeatherForecasts observable collection on a button click. Specify the type parameters explicitly to create an instance of the LineSeries class that consists of WeatherForecast objects.

@using System.Collections.ObjectModel

<DxButton Text="Add a new day"
          Click="(e) => GenerateNewItem()">
</DxButton>

<DxChart Data="@WeatherForecasts">
    <DxChartLineSeries T="WeatherForecast" TArgument="DateTime" TValue="int"
                       ArgumentField="@(s => s.Date)" ValueField="@(s => s.TemperatureC)" />
    <DxChartLegend Visible="false" />
</DxChart>

@code {
    int DaysNum { get; set; } = 30;
    static readonly Random random = new Random();
    ObservableCollection<WeatherForecast> WeatherForecasts { get; set; } = new ObservableCollection<WeatherForecast>();

    protected override void OnInitialized()
    {
        foreach (var date in Enumerable.Range(1, DaysNum).Select(i => DateTime.Now.Date.AddDays(i)))
        {
            GenerateNewItem();
        }
    }

    void GenerateNewItem()
    {
        WeatherForecasts.Add(new WeatherForecast()
        {
            Date = DateTime.Now.Date.AddDays(++DaysNum),
            TemperatureC = random.Next(10, 20)
        });
    }

    public class WeatherForecast {
        public DateTime Date { get; set; }
        public int TemperatureC { get; set; }
    }
}

Alternatively, you can call the RefreshData method to update data in the Chart bound to a collection that does not implement the INotifyCollectionChanged interface. To re-render the Chart area, call the RedrawAsync method.

Update a Navigation Component’s Data Source

The following code snippet shows how to use an ObservableCollection<T> object as a data source for the Menu component.

@using System.Collections.ObjectModel

<DxButton Text="Add Root Item" Click="(e) => AddNewRootItem()" />
<DxButton Text="Add Child Item" Click="(e) => AddNewChildItem()" />

<DxMenu Data="@MenuItems">
    <DataMappings>
        <DxMenuDataMapping Text="Text" Children="Children"/>
    </DataMappings>
</DxMenu>

@code {
    ObservableCollection<MenuItem> MenuItems { get; set; } = new ObservableCollection<MenuItem>() {
        new MenuItem("Item 1"),
        new MenuItem("Item 2"),
        new MenuItem("Item 3")
    };

    void AddNewRootItem() => MenuItems.Add(new MenuItem("New Item"));
    void AddNewChildItem() => MenuItems[0].Children.Add(new MenuItem("New SubItem"));

    class MenuItem {
        public string Text { get; private set; }
        public ObservableCollection<MenuItem> Children { get; } = new ObservableCollection<MenuItem>();
        public MenuItem(string text) => Text = text;
    }
}