Linq to Entity query criteria extension

1 usingSystem;2 usingSystem.Collections.Generic;3 usingSystem.Linq;4 usingSystem.Linq.Expressions;5 usingsystem.web;6 7 namespaceTest8 {9     /// <summary>Ten     ///Unified ParameterExpression One     /// </summary> A      Public classParameterreplacer:expressionvisitor -     { -          Publicparameterreplacer (parameterexpression paramexpr) the         { -ParameterExpression =paramexpr; -         } -  +          PublicParameterExpression ParameterExpression {Get;Private Set; } -  +          Publicexpression Replace (expression expr) A         { at             returnVisit (expr); -         } -  -         protected OverrideExpression visitparameter (parameterexpression p) -         { -             returnparameterexpression; in         } -     } to     /// <summary> +     ///predicate extension -     /// </summary> the      Public Static classpredicateextensionses *     { $         /// <summary>Panax Notoginseng         ///  -         /// </summary> the         /// <typeparam name= "T" ></typeparam> +         /// <returns></returns> A          Public StaticExpression<func<t,BOOL>> true<t> () {returnf =true; } the         /// <summary> +         ///  -         /// </summary> $         /// <typeparam name= "T" ></typeparam> $         /// <returns></returns> -          Public StaticExpression<func<t,BOOL>> false<t> () {returnf =false; } -         /// <summary> the         ///  -         /// </summary>Wuyi         /// <typeparam name= "T" ></typeparam> the         /// <param name= "Expleft" ></param> -         /// <param name= "Expright" ></param> Wu         /// <returns></returns> -          Public StaticExpression<func<t,BOOL>> and<t> ( ThisExpression<func<t,BOOL>> Expleft, Expression<func<t,BOOL>>expright) About         { $             varcandidateexpr = Expression.parameter (typeof(T),"candidate"); -             varParameterreplacer =NewParameterreplacer (candidateexpr); -  -             varleft =Parameterreplacer.replace (expleft.body); A             varright =Parameterreplacer.replace (expright.body); +             varBODY =Expression.and (left, right); the  -             returnExpression.lambda<func<t,BOOL>>(body, candidateexpr); $         } the         /// <summary> the         ///  the         /// </summary> the         /// <typeparam name= "T" ></typeparam> -         /// <param name= "Expleft" ></param> in         /// <param name= "Expright" ></param> the         /// <returns></returns> the          Public StaticExpression<func<t,BOOL>> or<t> ( ThisExpression<func<t,BOOL>> Expleft, Expression<func<t,BOOL>>expright) About         { the             varcandidateexpr = Expression.parameter (typeof(T),"candidate"); the             varParameterreplacer =NewParameterreplacer (candidateexpr); the  +             varleft =Parameterreplacer.replace (expleft.body); -             varright =Parameterreplacer.replace (expright.body); the             varBODY =expression.or (left, right);Bayi  the             returnExpression.lambda<func<t,BOOL>>(body, candidateexpr); the         } -     } -     /// <summary> the     ///queryable Extension the     /// </summary> the      Public Static classqueryableextensions the     { -         /// <summary> the         ///  the         /// </summary> the         /// <typeparam name= "T" ></typeparam>94         /// <param name= "queryable" ></param> the         /// <param name= "PropertyName" ></param> the         /// <returns></returns> the          Public StaticIqueryable<t> orderby<t> ( ThisIqueryable<t> queryable,stringPropertyName)98         { About             return(Queryable, PropertyName,false); -         }101         /// <summary>102         /// by103         /// </summary>104         /// <typeparam name= "T" >Entity</typeparam> the         /// <param name= "queryable" >conditions</param>106         /// <param name= "PropertyName" >Property name</param>107         /// <param name= "desc" >whether descending</param>108         /// <returns></returns>109          Public StaticIqueryable<t> orderby<t> ( ThisIqueryable<t> queryable,stringPropertyName,BOOLdesc) the         {111             varparam = Expression.parameter (typeof(T)); the             varBODY =expression.property (param, PropertyName);113             DynamicKeyselector =expression.lambda (body, param); the             returnDesc?queryable.orderbydescending (queryable, keyselector): Queryable.orderby (queryable, keyselector); the         } the     }117}

Linq to Entity query criteria extension