OrderByExpression.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / xsp / System / Extensions / UI / WebControls / Expressions / OrderByExpression.cs / 1305376 / OrderByExpression.cs
                        

                        
                            #if ORYX_VNEXT 
namespace Microsoft.Web.Data.UI.WebControls.Expressions {
    using System.Web;
    using System.Web.UI.WebControls;
#else 
namespace System.Web.UI.WebControls.Expressions {
#endif 
    using System; 
    using System.Collections.ObjectModel;
    using System.Diagnostics; 
    using System.Linq;
    using System.Linq.Expressions;
    using System.Web.Resources;
    using System.Web.UI; 

    [ 
    PersistChildren(false), 
    ParseChildren(true, "ThenByExpressions")
    ] 
    public class OrderByExpression : DataSourceExpression {
        private const string OrderByMethod = "OrderBy";
        private const string ThenByMethod = "ThenBy";
        private const string OrderDescendingByMethod = "OrderByDescending"; 
        private const string ThenDescendingByMethod = "ThenByDescending";
 
        private Collection _thenByExpressions; 

        public string DataField { 
            get {
                return (string)ViewState["DataField"] ?? String.Empty;
            }
            set { 
                ViewState["DataField"] = value;
            } 
        } 

        public SortDirection Direction { 
            get {
                object o = ViewState["Direction"];
                return o != null ? (SortDirection)o : SortDirection.Ascending;
            } 
            set {
                ViewState["Direction"] = value; 
            } 
        }
 
        [PersistenceMode(PersistenceMode.InnerDefaultProperty)]
        public Collection ThenByExpressions {
            get {
                if (_thenByExpressions == null) { 
                    //
                    _thenByExpressions = new Collection(); 
                } 
                return _thenByExpressions;
            } 
        }

        public override IQueryable GetQueryable(IQueryable source) {
            if (source == null) { 
                return null;
            } 
 
            if (String.IsNullOrEmpty(DataField)) {
                throw new InvalidOperationException(AtlasWeb.Expressions_DataFieldRequired); 
            }

            ParameterExpression pe = Expression.Parameter(source.ElementType, String.Empty);
            source = CreateSortQueryable(source, pe, Direction, DataField, false /* isThenBy */); 

            foreach (ThenBy thenBy in ThenByExpressions) { 
                source = CreateSortQueryable(source, pe, thenBy.Direction, thenBy.DataField, true /* isThenBy */); 
            }
 
            return source;
        }

        private static IQueryable CreateSortQueryable(IQueryable source, ParameterExpression parameterExpression, SortDirection direction, string dataField, bool isThenBy) { 
            string methodName = isThenBy ? GetThenBySortMethod(direction) : GetSortMethod(direction);
            Expression propertyExpression = ExpressionHelper.CreatePropertyExpression(parameterExpression, dataField); 
 
            return source.Call(methodName,
                               Expression.Lambda(propertyExpression, parameterExpression), 
                               source.ElementType,
                               propertyExpression.Type);
        }
 
        private static string GetSortMethod(SortDirection direction) {
            switch (direction) { 
                case SortDirection.Ascending: 
                    return OrderByMethod;
                case SortDirection.Descending: 
                    return OrderDescendingByMethod;
                default:
                    Debug.Fail("shouldn't get here!");
                    return OrderByMethod; 
            }
        } 
 
        private static string GetThenBySortMethod(SortDirection direction) {
            switch (direction) { 
                case SortDirection.Ascending:
                    return ThenByMethod;
                case SortDirection.Descending:
                    return ThenDescendingByMethod; 
                default:
                    Debug.Fail("shouldn't get here!"); 
                    return null; 
            }
        } 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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