ControlFilterExpression.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / xsp / System / DynamicData / DynamicData / ControlFilterExpression.cs / 1305376 / ControlFilterExpression.cs
                        
                        
                            using System.Collections.Generic; 
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Linq; 
using System.Linq.Expressions;
using System.Web.Resources; 
using System.Web.UI; 
using System.Web.UI.WebControls;
#if ORYX_VNEXT 
using Microsoft.Web.Data.UI.WebControls.Expressions;
using Microsoft.Web.Data.UI.WebControls;
#else
using System.Web.UI.WebControls.Expressions; 
#endif
 
namespace System.Web.DynamicData { 
    /// 
    /// A Dynamic Data-specific implementation of DataSourceExpression that modifies an IQueryable based on a data key (selected row) 
    /// in a data bound controls such as GridView, ListView, DetailsView, or FormView.
    /// If the Column property is left empty, the control treats the data key as the primary key of current table (this is useful
    /// in a List-Details scenario where the databound control and the datasource are displaying items of the same type). If the
    /// Column property is not empty, this control treats the data key as a foreign key (this is useful in a Parent-Children scenario, 
    /// where the databound control is displaying a list of Categories, and the data source is to be filtered to only display the
    /// Products that belong to the selected Category). 
    ///  
    public class ControlFilterExpression : DataSourceExpression {
        private PropertyExpression _propertyExpression; 
        /// 
        /// The ID of a data-bound control such as a GridView, ListView, DetailsView, or FormView whose data key will be used to build
        /// the expression that gets used in a QueryExtender.
        ///  
        [SuppressMessage("Microsoft.Naming", "CA1709:IdentifiersShouldBeCasedCorrectly", MessageId = "ID", Justification = "The property refers to the ID property of a Control")]
        public string ControlID { get; set; } 
 
        /// 
        /// Optional property which when set indicates that the data key should be treated as a foreign key. 
        /// 
        public string Column { get; set; }

        private PropertyExpression Expression { 
            get {
                if (_propertyExpression == null) { 
                    _propertyExpression = new PropertyExpression(); 
                }
                return _propertyExpression; 
            }
        }

        public override void SetContext(Control owner, HttpContext context, IQueryableDataSource dataSource) { 
            base.SetContext(owner, context, dataSource);
 
            Owner.Page.InitComplete += new EventHandler(Page_InitComplete); 
            Owner.Page.LoadComplete += new EventHandler(Page_LoadComplete);
        } 

        private void Page_InitComplete(object sender, EventArgs e) {
            if (!Owner.Page.IsPostBack) {
                // Do not reconfigure the Expression on postback. It's values should be preserved via ViewState. 
                Control control = FindTargetControl();
                MetaTable table = DataSource.GetMetaTable(); 
 
                if (String.IsNullOrEmpty(Column)) {
                    foreach (var param in GetPrimaryKeyControlParameters(control, table)) { 
                        Expression.Parameters.Add(param);
                    }
                } else {
                    MetaForeignKeyColumn column = (MetaForeignKeyColumn)table.GetColumn(Column); 
                    foreach (var param in GetForeignKeyControlParameters(control, column)) {
                        Expression.Parameters.Add(param); 
                    } 
                }
            } 

            Expression.SetContext(Owner, Context, DataSource);
        }
 
        private Control FindTargetControl() {
            Control control = Misc.FindControl(Owner, ControlID); 
            if (control == null) { 
                throw new InvalidOperationException(String.Format(CultureInfo.CurrentCulture,
                    DynamicDataResources.ControlFilterExpression_CouldNotFindControlID, 
                    Owner.ID,
                    ControlID));
            }
            return control; 
        }
 
        private void Page_LoadComplete(object sender, EventArgs e) { 
            Expression.Parameters.UpdateValues(Context, Owner);
        } 

        protected override object SaveViewState() {
            Pair p = new Pair();
            p.First = base.SaveViewState(); 
            p.Second = ((IStateManager)Expression.Parameters).SaveViewState();
            return p; 
        } 

        protected override void LoadViewState(object savedState) { 
            Pair p = (Pair)savedState;
            base.LoadViewState(p.First);
            if (p.Second != null) {
                ((IStateManager)Expression.Parameters).LoadViewState(p.Second); 
            }
        } 
 
        protected override void TrackViewState() {
            base.TrackViewState(); 
            ((IStateManager)Expression.Parameters).TrackViewState();
        }

        private IEnumerable GetPrimaryKeyControlParameters(Control control, MetaTable table) { 
            // For each PK column in the table, we need to create a ControlParameter
            var nameColumnMapping = table.PrimaryKeyColumns.ToDictionary(c => c.Name); 
            return GetControlParameters(control, nameColumnMapping); 
        }
 
        private IEnumerable GetForeignKeyControlParameters(Control control, MetaForeignKeyColumn column) {
            // For each underlying FK, we need to create a ControlParameter
            MetaTable otherTable = column.ParentTable;
            Dictionary nameColumnMapping = CreateColumnMapping(column, otherTable.PrimaryKeyColumns); 
            return GetControlParameters(control, nameColumnMapping);
        } 
 
        private static Dictionary CreateColumnMapping(MetaForeignKeyColumn column, IList columns) {
            var names = column.ForeignKeyNames; 
            Debug.Assert(names.Count == columns.Count);
            Dictionary nameColumnMapping = new Dictionary();
            for (int i = 0; i < names.Count; i++) {
                // Get the filter expression for this foreign key name 
                string filterExpression = column.GetFilterExpression(names[i]);
                nameColumnMapping[filterExpression] = columns[i]; 
            } 
            return nameColumnMapping;
        } 

        internal static IEnumerable GetControlParameters(Control control, IDictionary nameColumnMapping) {
            IControlParameterTarget target = null;
 
            target = DynamicDataManager.GetControlParameterTarget(control);
            Debug.Assert(target != null); 
 
            foreach (var entry in nameColumnMapping) {
                string parameterName = entry.Key; 
                MetaColumn column = entry.Value;

                ControlParameter controlParameter = new ControlParameter() {
                    Name = parameterName, 
                    ControlID = control.UniqueID
                }; 
                if (target != null) { 
                    // this means the relationship consists of more than one key and we need to expand the property name
                    controlParameter.PropertyName = target.GetPropertyNameExpression(column.Name); 
                }
                DataSourceUtil.SetParameterTypeCodeAndDbType(controlParameter, column);
                yield return controlParameter;
            } 
        }
 
        public override IQueryable GetQueryable(IQueryable source) { 
            return Expression.GetQueryable(source);
        } 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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ControlFilterExpression.cs source code in C# .NET

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