106 lines
3.8 KiB
C#
106 lines
3.8 KiB
C#
namespace System.Web.UI.WebControls.Expressions {
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using System;
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using System.Collections.ObjectModel;
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using System.Diagnostics;
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using System.Linq;
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using System.Linq.Expressions;
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using System.Web.Resources;
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using System.Web.UI;
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[
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PersistChildren(false),
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ParseChildren(true, "ThenByExpressions")
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]
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public class OrderByExpression : DataSourceExpression {
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private const string OrderByMethod = "OrderBy";
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private const string ThenByMethod = "ThenBy";
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private const string OrderDescendingByMethod = "OrderByDescending";
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private const string ThenDescendingByMethod = "ThenByDescending";
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private Collection<ThenBy> _thenByExpressions;
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public string DataField {
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get {
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return (string)ViewState["DataField"] ?? String.Empty;
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}
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set {
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ViewState["DataField"] = value;
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}
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}
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public SortDirection Direction {
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get {
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object o = ViewState["Direction"];
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return o != null ? (SortDirection)o : SortDirection.Ascending;
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}
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set {
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ViewState["Direction"] = value;
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}
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}
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[PersistenceMode(PersistenceMode.InnerDefaultProperty)]
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public Collection<ThenBy> ThenByExpressions {
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get {
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if (_thenByExpressions == null) {
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//
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_thenByExpressions = new Collection<ThenBy>();
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}
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return _thenByExpressions;
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}
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}
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public override IQueryable GetQueryable(IQueryable source) {
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if (source == null) {
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return null;
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}
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if (String.IsNullOrEmpty(DataField)) {
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throw new InvalidOperationException(AtlasWeb.Expressions_DataFieldRequired);
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}
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ParameterExpression pe = Expression.Parameter(source.ElementType, String.Empty);
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source = CreateSortQueryable(source, pe, Direction, DataField, false /* isThenBy */);
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foreach (ThenBy thenBy in ThenByExpressions) {
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source = CreateSortQueryable(source, pe, thenBy.Direction, thenBy.DataField, true /* isThenBy */);
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}
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return source;
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}
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private static IQueryable CreateSortQueryable(IQueryable source, ParameterExpression parameterExpression, SortDirection direction, string dataField, bool isThenBy) {
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string methodName = isThenBy ? GetThenBySortMethod(direction) : GetSortMethod(direction);
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Expression propertyExpression = ExpressionHelper.CreatePropertyExpression(parameterExpression, dataField);
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return source.Call(methodName,
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Expression.Lambda(propertyExpression, parameterExpression),
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source.ElementType,
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propertyExpression.Type);
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}
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private static string GetSortMethod(SortDirection direction) {
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switch (direction) {
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case SortDirection.Ascending:
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return OrderByMethod;
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case SortDirection.Descending:
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return OrderDescendingByMethod;
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default:
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Debug.Fail("shouldn't get here!");
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return OrderByMethod;
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}
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}
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private static string GetThenBySortMethod(SortDirection direction) {
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switch (direction) {
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case SortDirection.Ascending:
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return ThenByMethod;
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case SortDirection.Descending:
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return ThenDescendingByMethod;
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default:
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Debug.Fail("shouldn't get here!");
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return null;
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}
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}
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}
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}
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