c# 表达式树问题。求大侠帮忙改造一下谢谢

悬赏园豆：30 [已解决问题] 解决于 2017-06-15 10:52

这个是jQuery-QueryBuilder的一个插件构造查询。

UI地址 http://querybuilder.js.org/index.html

对于的c#代码转化。

https://github.com/castle-it/dynamic-linq-query-builder

上面一段只是介绍可以忽略

问题开始了。

这个是js在前台转化的。希望改成c# 作者也提提供了c# 但是他用的是表达式树本人不是特别的熟悉把他的关键代码贴出来

        /// <summary>
        /// Gets the filtered collection after applying the provided filter rules. 
        /// Returns the string representation for diagnostic purposes.
        /// </summary>
        /// <typeparam name="T">The generic type.</typeparam>
        /// <param name="queryable">The queryable.</param>
        /// <param name="filterRule">The filter rule.</param>
        /// <param name="parsedQuery">The parsed query.</param>
        /// <param name="useIndexedProperty">Whether or not to use indexed property</param>
        /// <param name="indexedPropertyName">The indexable property to use</param>
        /// <returns>Filtered IQueryable.</returns>
        public static IQueryable<T> BuildQuery<T>(this IQueryable<T> queryable, FilterRule filterRule, out string parsedQuery, bool useIndexedProperty = false, string indexedPropertyName = null)
        {
            if (filterRule == null)
            {
                parsedQuery = "";
                return queryable;
            }

            var pe = Expression.Parameter(typeof(T), "item");

            var expressionTree = BuildExpressionTree(pe, filterRule, useIndexedProperty, indexedPropertyName);
            if (expressionTree == null)
            {
                parsedQuery = "";
                return queryable;
            }

            parsedQuery = expressionTree.ToString();

            var whereCallExpression = Expression.Call(
                typeof(Queryable),
                "Where",
                new[] { queryable.ElementType },
                queryable.Expression,
                Expression.Lambda<Func<T, bool>>(expressionTree, pe));

            var filteredResults = queryable.Provider.CreateQuery<T>(whereCallExpression);

            return filteredResults;

        }