Example

using System.Collections;
using System.ServiceModel.DomainServices.Client;
using System.Windows;
using HowToSamples.Web;
using Intersoft.Client.Data.ComponentModel;
using Intersoft.Client.Data.Provider.Ria;
using Intersoft.Client.Framework.Input;


namespace HowToSamples.ViewModels
{
    public class FilterFormViewModel : ViewModelBase
    {
        public FilterFormViewModel()
        {
            this.QueryDescriptor = new QueryDescriptor();
            this.Manager = new NorthwindDomainContext();
            this.DoFilter = new DelegateCommand(ExecuteDoFilter);

            this.LoadProducts();
        }

        private bool? _filterDiscontinued;
        private string _filterName;
        private IEnumerable _products;
        private QueryDescriptor _queryDescriptor;
        
        public DelegateCommand DoFilter { get; set; }
        private NorthwindDomainContext Manager { get; set; }

        public IEnumerable Products
        {
            get { return this._products; }
            set
            {
                if (this._products != value)
                {
                    this._products = value;
                    this.OnPropertyChanged("Products");
                }
            }
        }

        public bool? FilterDiscontinued
        {
            get
            {
                return this._filterDiscontinued;
            }
            set
            {
                if (this._filterDiscontinued != value)
                {
                    this._filterDiscontinued = value;
                    this.OnPropertyChanged("FilterDiscontinued");
                }
            }
        }

        public string FilterName
        {
            get
            {
                return this._filterName;
            }
            set
            {
                if (this._filterName != value)
                {
                    this._filterName = value;
                    this.OnPropertyChanged("FilterName");
                }
            }
        }

        public QueryDescriptor QueryDescriptor
        {
            get
            {
                return this._queryDescriptor;
            }
            set
            {
                if (this._queryDescriptor != value)
                {                    
                    this._queryDescriptor = value;
                    this.OnPropertyChanged("QueryDescriptor");
                }
            }
        }

        public void ExecuteDoFilter(object parameter)
        {
            this.QueryDescriptor.FilterDescriptors.Clear();

            if (!string.IsNullOrEmpty(this.FilterName))
            {
                FilterDescriptor filterName = new FilterDescriptor() { PropertyName = "ProductName", Operator = FilterOperator.StartsWith, Value = this.FilterName };
                this.QueryDescriptor.FilterDescriptors.Add(filterName);
            }

            if (this.FilterDiscontinued.HasValue)
            {
                FilterDescriptor filterDiscontinued = new FilterDescriptor() { PropertyName = "Discontinued", Operator = FilterOperator.IsEqualTo, Value = this.FilterDiscontinued.Value };
                this.QueryDescriptor.FilterDescriptors.Add(filterDiscontinued);
            }            

            this.LoadProducts();
        }

        public virtual void LoadProducts()
        {
            if (Intersoft.Client.Framework.ISControl.IsInDesignModeStatic)
                return;

            var query = this.Manager.GetProductsQuery().OrderBy(p => p.ProductID).Parse(this.QueryDescriptor);
            
            this.Manager.Load(
               query,
               op =>
               {
                   if (op.IsComplete)
                   {
                       this.Products = new PagedCollectionView(op.Entities);                       
                   }
                   else
                   {
                       MessageBox.Show(op.Error.ToString());
                   }
               },

               true);
        }
    }
}