This example shows how to implement asynchronous DataListProvider in UXPropertyGrid.

Example

Description

UXPropertyGrid comes with built-in items editor, which will be use UXComboBox by default. To use this editor type, you just need to provide the data which will be served in the editor. In this example, you will learn how to implement DataListProvider in asynchronous way. To implement it in synchronous way, you can refer to How To Implement Synchronous DataListProvider in UXPropertyGrid. To learn more about UXPropertyGrid, see UXPropertyGrid Overview.

Scenario

In this scenario, items editor will be applied on ReportsTo property. Of course, EmployeeName will be used here as the displayed property value, instead of EmployeeID.

Code

In the following code, an object (Employee) will be bound into UXPropertyGrid.

XAML	Copy Code
<Intersoft:UXPropertyGrid SelectedObject="{Binding Employee}"/>

To use DataListProvider, you need to derive it from EditorDataProvider class. To perform the get data operation in asynchronous way, there are some members that needed to be implemented, such as IsAsync, DisplayMemberPath, SelectedValuePath, BeginSingleAsync, and BeginGetDataAsync, which can be seen in the following code.

C#	Copy Code
public class EmployeeDataListProvider : EditorDataProvider { #region Properties public override bool IsAsync { get; set; } private IDataRepository DataSource { get { return EmployeesRepository.Instance; } } #endregion #region Constructors public CategoryDataListProvider() { this.IsAsync = true; this.DisplayMemberPath = "FirstName"; this.SelectedValuePath = "EmployeeID"; } #endregion #region Methods public override object BeginSingleAsync(object item) { PropertyGridDefinition propertyDefinition = item as PropertyGridDefinition; int employeeID = 0; if (propertyDefinition != null && propertyDefinition.Value != null) employeeID = (int)propertyDefinition.Value; QueryDescriptor queryDescriptor = new QueryDescriptor(); queryDescriptor.FilterDescriptors.Add(new FilterDescriptor("EmployeeID", FilterOperator.IsEqualTo, employeeID)); this.DataSource.GetData( queryDescriptor, (items) => { this.EndGetSingleAsync(token, items.OfType<object>().FirstOrDefault()); } ); } public override void BeginGetDataAsync(Guid token) { if (this.DataSource != null) { this.DataSource.GetData( (items) => { this.EndGetDataAsync(token, items); } ); } } #endregion }

Copy Code

public class EmployeeDataListProvider : EditorDataProvider
{                        
    #region Properties
                        
    public override bool IsAsync { get; set; }

    private IDataRepository DataSource
    {
        get { return EmployeesRepository.Instance; }
    }

    #endregion
                        
    #region Constructors

    public CategoryDataListProvider()
    {
        this.IsAsync = true;
        this.DisplayMemberPath = "FirstName";
        this.SelectedValuePath = "EmployeeID";
    }

    #endregion
                        
    #region Methods
                        
    public override object BeginSingleAsync(object item)
    {
        PropertyGridDefinition propertyDefinition = item as PropertyGridDefinition;

        int employeeID = 0;

        if (propertyDefinition != null && propertyDefinition.Value != null)
            employeeID = (int)propertyDefinition.Value;
                        
        QueryDescriptor queryDescriptor = new QueryDescriptor();
        queryDescriptor.FilterDescriptors.Add(new FilterDescriptor("EmployeeID", FilterOperator.IsEqualTo, employeeID));

        this.DataSource.GetData(
            queryDescriptor,
            (items) =>
            {
                this.EndGetSingleAsync(token, items.OfType<object>().FirstOrDefault());
            }
        );
    }
                        
    public override void BeginGetDataAsync(Guid token)
    {
        if (this.DataSource != null)
        {
            this.DataSource.GetData(
                (items) =>
                {
                    this.EndGetDataAsync(token, items);
                }
            );
        }
    }
                        
    #endregion
}

Besides that, you also need to decorate ReportsTo property with DataListProvider attribute, like the below code.

C#	Copy Code
[DataListProvider(typeof(Intersoft.ClientUI.Samples.Editors.DataListProvider.EmployeeDataListProvider))] public int? ReportsTo { get; set; }

Result

The code above will produce the results which will look like the following image:

Concepts

UXPropertyGrid