Dynamic LINQ to Entities Queries Using WCF/WPF Demo Code

using System.Windows;
using System.Windows.Controls;
using System;
using WpfClient.Commands;
using System.Collections.Generic;


namespace WpfClient.UserControls
{

    public delegate void SearchRequestedEventHandler(object sender, SearchEventArgs e);


    /// <summary>
    /// Interaction logic for SearchControl.xaml
    /// </summary>
    public partial class SearchControl : UserControl
    {

        #region Data
        private RelayCommand addSearchCommand;
        private RelayCommand runSearch;
        #endregion

        #region Ctor
        public SearchControl()
        {
            InitializeComponent();
            this.DataContext = this;
        }
        #endregion

        #region BoundType DP

        #region BoundType

        /// <summary>
        /// IsAvailable Dependency Property
        /// </summary>
        public static readonly DependencyProperty BoundTypeProperty =
            DependencyProperty.Register("BoundType", 
                typeof(System.Type), typeof(SearchControl),
                    new FrameworkPropertyMetadata(null,
                        new PropertyChangedCallback(OnBoundTypeChanged)));

        /// <summary>
        /// Gets or sets the BoundCustomer property.  
        /// </summary>
        public Type BoundType
        {
            get { return (Type)GetValue(BoundTypeProperty); }
            set { SetValue(BoundTypeProperty, value); }
        }

        /// <summary>
        /// Handles changes to the BoundType property.
        /// </summary>
        private static void OnBoundTypeChanged(DependencyObject d,
            DependencyPropertyChangedEventArgs e)
        {
            Type currentObject = e.NewValue.GetType();

            if (currentObject != null)
            {
                SearchControl searchControl = (SearchControl)d;
                foreach (SearchClauseControl searchClause in searchControl.spSearchClauses.Children)
                {
                    searchClause.BoundType = searchControl.BoundType;
                }
                searchControl.ReEstablishFirstClause();
            }
        }


        #endregion


        #endregion

        #region CLR Properties
        private String Query { get; set; }
        #endregion

        #region Routed Events
        public static readonly RoutedEvent SearchRequestedEvent =
            EventManager.RegisterRoutedEvent(
            "SearchRequested", RoutingStrategy.Bubble,
            typeof(SearchRequestedEventHandler),
            typeof(SearchControl));

        //add remove handlers
        public event SearchRequestedEventHandler SearchRequested
        {
            add { AddHandler(SearchRequestedEvent, value); }
            remove { RemoveHandler(SearchRequestedEvent, value); }
        }

        #endregion

        #region Commands
        public RelayCommand AddSearchCommand
        {
            get
            {
                if (addSearchCommand == null)
                {
                    addSearchCommand = new RelayCommand(
                        param => { return true;},
                        param =>
                            {
                                AddSearchClause();
                            }
                        );
                }
                return addSearchCommand;
            }
        }


        public RelayCommand RunSearchCommand
        {
            get
            {
                if (runSearch == null)
                {
                    runSearch = new RelayCommand(
                        param => { return true; },
                        param =>
                        {
                            RunSearch();
                        }
                        );
                }
                return runSearch;
            }
        }
        #endregion

        #region Public Methods
        public void Initialise()
        {
            spSearchClauses.Children.Clear();
        }

        #endregion

        #region Private Methods
        private void AddSearchClause()
        {
            SearchClauseControl searchClause = new SearchClauseControl();
            searchClause.BoundType = this.BoundType;
            searchClause.CloseSearchClause += searchClause_CloseSearchClause;
            spSearchClauses.Children.Add(searchClause);
            ReEstablishFirstClause();
        }

        private void searchClause_CloseSearchClause(object sender, System.Windows.RoutedEventArgs e)
        {
            spSearchClauses.Children.Remove(sender as SearchClauseControl);
            ReEstablishFirstClause();
        }

        private void ReEstablishFirstClause()
        {
            for (Int32 i = 0; i < spSearchClauses.Children.Count; i++)
            {
                (spSearchClauses.Children[i] as SearchClauseControl).IsFirst = i == 0 ? true : false;
                (spSearchClauses.Children[i] as SearchClauseControl).ParameterNumber = i;
            }
        }

        private void RunSearch()
        {
            Query = String.Empty;

            List<Object> searchParameters = new List<Object>();
            
            for (int i = 0; i < spSearchClauses.Children.Count; i++)
            {
                SearchClauseControl searchClauseControl = spSearchClauses.Children[i] as SearchClauseControl;
                //work out wording
                if (i == 0)
                    Query += searchClauseControl.ClauseResult;
                else
                    Query += " " + searchClauseControl.ClauseResult;

                //and store parameter value
                if (searchClauseControl.IsString)
                {
                    searchParameters.Add(searchClauseControl.CurrentValue);
                }
                else
                {
                    try
                    {
                        searchParameters.Add(Int32.Parse(searchClauseControl.CurrentValue));
                    }
                    catch (FormatException)
                    {
                        MessageBox.Show("Could convert one of the search parameter values");
                    }
                }


            }

            SearchEventArgs args =
                new SearchEventArgs(
                    SearchRequestedEvent,
                    searchParameters,
                    this.Query);
            RaiseEvent(args);
        }
        #endregion
    }
}