linq or拓展

场景：EF多条件查询时候，遇到多个or的情况

拓展类

  #region linq or拓展
    public static class Utility
    {
        public static Expression Compose(this Expression first, Expression second, Func merge)
        {
            // build parameter map (from parameters of second to parameters of first)
            var map = first.Parameters.Select((f, i) => new { f, s = second.Parameters[i] }).ToDictionary(p => p.s, p => p.f);
            // replace parameters in the second lambda expression with parameters from the first
            var secondBody = ParameterRebinder.ReplaceParameters(map, second.Body);
            // apply composition of lambda expression bodies to parameters from the first expression
            return Expression.Lambda(merge(first.Body, secondBody), first.Parameters);
        }
        public static Expressionbool>> And(this Expressionbool>> first, Expressionbool>> second)
        {
            return first.Compose(second, Expression.And);
        }
        public static Expressionbool>> Or(this Expressionbool>> first, Expressionbool>> second)
        {
            return first.Compose(second, Expression.Or);
        }
    }
    public class ParameterRebinder : ExpressionVisitor
    {

        private readonly Dictionary map;
        public ParameterRebinder(Dictionary map)
        {
            this.map = map ?? new Dictionary();
        }

        public static Expression ReplaceParameters(Dictionary map, Expression exp)
        {
            return new ParameterRebinder(map).Visit(exp);
        }
        protected override Expression VisitParameter(ParameterExpression p)
        {
            ParameterExpression replacement;
            if (map.TryGetValue(p, out replacement))
            {
                p = replacement;
            }
            return base.VisitParameter(p);
        }
    }
    #endregion

用法

  IQueryable commentListTemp = reviewHistoryEntities.RakutenGoodsReviewLists.Where(r => r.GoodsReviewID.StartsWith(userShop.ShopID + "_"));
                                
                                        //判断商品名
                                        if (!string.IsNullOrWhiteSpace(this.tbGoodsNameReviewGoods.Text))
                                        {
                                            commentListTemp = commentListTemp.Where(r => r.RakutenGoodsReview.GoodsName.Contains(tbGoodsNameReviewGoods.Text.Trim()));
                                        }
                                        //判断商品id    such as：10000000,12312,213,2312
                                        if (!string.IsNullOrWhiteSpace(this.tbGoodsIDReviewGoods.Text))
                                        {
                                            string[] ids = tbGoodsIDReviewGoods.Text.Split(new char[] { (',') }, StringSplitOptions.RemoveEmptyEntries);
                                            if (ids.Length > 500)
                                            {
                                                base.ShowErrorMessage("商品ID: 500個以内に設定してください。", uplRank);
                                                return;
                                            }
                                            Expressionbool>> orQuery = q => false;
                                            for (int i = 0; i < ids.Length; i++)
                                            {
                                                string id = ids[i];
                                                orQuery = orQuery.Or(q => q.GoodsReviewID.IndexOf("_" + id) > -1);
                                            }
                                            commentListTemp = commentListTemp.Where(orQuery);
                                        }
                                        //判断关键字
                                        if (!string.IsNullOrWhiteSpace(tbCommentUserReviewGoods.Text))
                                        {
                                            commentListTemp = commentListTemp.Where(r => r.UserName.Contains(tbCommentUserReviewGoods.Text.Trim()));
                                        }

执行时候生成的sql语句

--数据可能会被截断并且可能无法表示服务器上运行的查询。
USE [ReviewHistory];

GO

--类型和值数据不适用于下列变量。它们的值已设为默认值。
DECLARE @p__linq__0 AS SQL_VARIANT;
DECLARE @p__linq__1 AS SQL_VARIANT;
DECLARE @p__linq__2 AS SQL_VARIANT;
DECLARE @p__linq__3 AS SQL_VARIANT;
DECLARE @p__linq__4 AS SQL_VARIANT;
DECLARE @p__linq__5 AS SQL_VARIANT;
DECLARE @p__linq__6 AS SQL_VARIANT;
DECLARE @p__linq__7 AS SQL_VARIANT;
SET @p__linq__0 = NULL;
SET @p__linq__1 = NULL;
SET @p__linq__2 = NULL;
SET @p__linq__3 = NULL;
SET @p__linq__4 = NULL;
SET @p__linq__5 = NULL;
SET @p__linq__6 = NULL;
SET @p__linq__7 = NULL;

SELECT 
[Extent1].[ID] AS [ID], 
[Extent1].[GoodsReviewID] AS [GoodsReviewID], 
[Extent1].[UserPicture] AS [UserPicture], 
[Extent1].[UserName] AS [UserName], 
[Extent1].[UserSex] AS [UserSex], 
[Extent1].[UserReviewScore] AS [UserReviewScore], 
[Extent1].[UserReviewTitle] AS [UserReviewTitle], 
[Extent1].[UserReviewContent] AS [UserReviewContent], 
[Extent1].[UserReviewTime] AS [UserReviewTime], 
[Extent1].[IsAfterBuyReview] AS [IsAfterBuyReview], 
[Extent1].[UserUseInfo] AS [UserUseInfo], 
[Extent1].[HelpedCount] AS [HelpedCount], 
[Extent1].[UserReviewUrl] AS [UserReviewUrl], 
[Extent1].[SaveTime] AS [SaveTime], 
[Extent1].[ExtraField1] AS [ExtraField1], 
[Extent1].[ExtraField2] AS [ExtraField2], 
[Extent1].[ExtraField3] AS [ExtraField3], 
[Extent1].[ExtraField4] AS [ExtraField4], 
[Extent1].[ExtraField5] AS [ExtraField5]
FROM [dbo].[YahooGoodsReviewList] AS [Extent1]
WHERE (( CAST(CHARINDEX(@p__linq__0 + N'_', [Extent1].[GoodsReviewID]) AS int)) = 1) AND ((( CAST(CHARINDEX(N'_' + @p__linq__1, [Extent1].[GoodsReviewID]) AS int)) > 0) OR (( CAST(CHARINDEX(N'_' + @p__linq__2, [Extent1].[GoodsReviewID]) AS int)) > 0) OR (( CAST(CHARINDEX(N'_' + @p__linq__3, [Extent1].[GoodsReviewID]) AS int)) > 0) OR (( CAST(CHARINDEX(N'_' + @p__linq__4, [Extent1].[GoodsReviewID]) AS int)) > 0) OR (( CAST(CHARINDEX(N'_' + @p__linq__5, [Extent1].[GoodsReviewID]) AS int)) > 0) OR (( CAST(CHARINDEX(N'_' + @p__linq__6, [Extent1].[GoodsReviewID]) AS int)) > 0) OR (( CAST(CHARINDEX(N'_' + @p__linq__7, [Extent1].[GoodsReviewID]) AS int)) > 0))