DxTreeViewDataMapping Class

Maps TreeView node properties to data source fields.

Assembly: DevExpress.Blazor.v22.1.dll

Declaration

public class DxTreeViewDataMapping :
    DxTreeViewDataMappingBase

Remarks

The TreeView component supports binding to data. In bound mode, items from the data source automatically populate TreeView nodes.

Follow the steps below to bind TreeView to data:

Use the Data property to specify a data source. You can use different data types:
- Flat data - a collection of items that are available at one level.
- Hierarchical data - a collection of nested nodes.
Add the DataMappings tag to the component’s markup.
Create the DxTreeViewDataMapping instance and map node properties (HasChildren, IconCssClass, and so on) to data source fields. Mappings are used to link the TreeView data model to the data source.
- Flat data - the Key and ParentKey properties are required. If the TreeView’s structure consists of only one level, you can omit these properties.
- Hierarchical data - the Children property is required.
You can also create multiple DxTreeViewDataMapping instances to specify different mappings for different node levels. Use the Level property to specify the node level for which data mappings are applied.

Flat Data

The code below binds the TreeView to the collection of flat data items. It specifies mappings for the Text, Key, and ParentKey properties.

Razor
FlatDataItem.cs

@if(Data == null) {
    <p><em>Loading...</em></p>
}
else {
    <div class="cw-320">
        <DxTreeView Data="@Data">
            <DataMappings>
                <DxTreeViewDataMapping Text="Name"
                                       Key="Id"
                                       ParentKey="CategoryId" />
            </DataMappings>
        </DxTreeView>
    </div>
}

@code {
    List<FlatDataItem> Data { get; set; }

    protected override void OnInitialized() {
        IEnumerable<ProductFlat> products = ProductData.Products;
        IEnumerable<ProductCategory> productSubcategories = ProductData.Categories;

        Data = new List<FlatDataItem>(Enum.GetValues<ProductCategoryMain>().Select(i => new FlatDataItem() { Name = i.ToString(), Id = i }));
        Data.AddRange(products.Select(i => new FlatDataItem() { Name = i.ProductName, Id = i.Id, CategoryId = i.ProductCategoryId }));
        Data.AddRange(productSubcategories.Select(i => new FlatDataItem() { Name = i.Subcategory, Id = i.SubcategoryID, CategoryId = i.Category }));
    }
}

namespace BlazorDemo.Data {
    public class FlatDataItem {
        public string Name { get; set; }
        public object Id { get; set; }
        public object CategoryId { get; set; }
    }
}

Bind Treview to Flat Data

Run Demo: TreeView - Binding to Flat Data

Hierarchical Data

The code below binds the TreeView to the collection of ChemicalElementGroup objects. Each object can have child objects. The code specifies the Children and Text mappings to adjust the TreeView data model to the specified data source.

Razor
ChemicalElements.cs

<DxTreeView Data="@ChemicalElements.Groups">
    <DataMappings>
        <DxTreeViewDataMapping Children="Groups"
                               Text="Name"/>
    </DataMappings>
</DxTreeView>

using System;
using System.Collections.Generic;

namespace BlazorDemo.Data {
    public static class ChemicalElements {
        private static readonly Lazy<List<ChemicalElementGroup>> chemicalElementGroups = new Lazy<List<ChemicalElementGroup>>(() => {
            List<ChemicalElementGroup> groups = new List<ChemicalElementGroup>() {
                new ChemicalElementGroup("Metals", new List<ChemicalElementGroup>() {
                    new ChemicalElementGroup("Alkali metals"),
                    new ChemicalElementGroup("Alkaline earth metals"),
                    new ChemicalElementGroup("Inner transition elements", new List<ChemicalElementGroup>() {
                        new ChemicalElementGroup("Lanthanides"),
                        new ChemicalElementGroup("Actinides")
                    }),
                    new ChemicalElementGroup("Transition elements"),
                    new ChemicalElementGroup("Other metals")
                }),
                new ChemicalElementGroup("Metalloids"),
                new ChemicalElementGroup("Nonmetals", new List<ChemicalElementGroup>() {
                    new ChemicalElementGroup("Halogens"),
                    new ChemicalElementGroup("Noble gases"),
                    new ChemicalElementGroup("Other nonmetals")
                })
            };
            return groups;
        });

        public static List<ChemicalElementGroup> Groups { get { return chemicalElementGroups.Value; } }
    }
}

Bind Treview to Hierarchical Data