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namespace System.Web.UI.WebControls.Expressions {
using System;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Linq.Expressions;
using System.Web.Resources;
using System.Web.UI;
using System.Web.UI.WebControls;
public class SearchExpression : ParameterDataSourceExpression {
public string DataFields {
get {
return (string)ViewState["DataFields"] ?? String.Empty;
}
set {
ViewState["DataFields"] = value;
}
}
public SearchType SearchType {
get {
object o = ViewState["SearchType"];
return o != null ? (SearchType)o : SearchType.StartsWith;
}
set {
ViewState["SearchType"] = value;
}
}
public StringComparison ComparisonType {
get {
object o = ViewState["ComparisonType"];
return o != null ? (StringComparison)o : StringComparison.OrdinalIgnoreCase;
}
set {
ViewState["ComparisonType"] = value;
}
}
public override IQueryable GetQueryable(IQueryable source) {
if (source == null) {
return null;
}
if ((DataFields == null) || String.IsNullOrEmpty(DataFields.Trim())) {
throw new InvalidOperationException(AtlasWeb.Expressions_DataFieldRequired);
}
IDictionary<string, object> values = GetValues();
if (values.Count == 0) {
throw new InvalidOperationException(AtlasWeb.SearchExpression_ParameterRequired);
}
string query = Convert.ToString(values.First().Value, CultureInfo.CurrentCulture);
if (String.IsNullOrEmpty(query)) {
return null;
}
string[] properties = DataFields.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
// Use the or expression to or the fields together
List<Expression> searchExpressions = new List<Expression>();
ParameterExpression parameterExpression = Expression.Parameter(source.ElementType, String.Empty);
foreach (string p in properties) {
Expression property = ExpressionHelper.CreatePropertyExpression(parameterExpression, p.Trim());
searchExpressions.Add(CreateCallExpression(property, query));
}
return ExpressionHelper.Where(source,
Expression.Lambda(ExpressionHelper.Or(searchExpressions),
parameterExpression));
}
private Expression CreateCallExpression(Expression property, string query) {
// LINQ to SQL does not support the overloads StartsWith(string, StringComparer) or EndsWith(string, StringComparer)
// and Contains has not overload that takes a StringComparer
if (SearchType == SearchType.Contains || (ViewState["ComparisonType"] == null)) {
return Expression.Call(property, SearchType.ToString(), Type.EmptyTypes, Expression.Constant(query, property.Type));
}
return Expression.Call(property, SearchType.ToString(), Type.EmptyTypes, Expression.Constant(query, property.Type), Expression.Constant(ComparisonType));
}
}
}
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