List实现行转列的通用方案

最近在做报表统计方面的需求，涉及到行转列报表。根据以往经验使用SQL可以比较容易完成，这次决定挑战一下直接通过代码方式完成行转列。期间遇到几个问题和用到的新知识这里整理记录一下。

 

问题介绍

　　以家庭月度费用为例，可以在[Name,Area,Month]三个维度上随意组合进行分组，三个维度中选择一个做为列显示。

    /// <summary>
    /// 家庭费用情况
    /// </summary>
    public class House
    {
        /// <summary>
        /// 户主姓名
        /// </summary>
        public string Name { get; set; }

        /// <summary>
        /// 所属行政区域
        /// </summary>
        public string Area { get; set; }

        /// <summary>
        /// 月份
        /// </summary>
        public string Month { get; set; }

        /// <summary>
        /// 电费金额
        /// </summary>
        public double DfMoney { get; set; }

        /// <summary>
        /// 水费金额
        /// </summary>
        public double SfMoney { get; set; }

        /// <summary>
        /// 燃气金额
        /// </summary>
        public double RqfMoney { get; set; }
    }

户主-月明细报表
户主姓名	2016-01			2016-02
	电费	水费	燃气费	电费	水费	燃气费
张三	240.9	30	25	167	24.5	17.9
李四	56.7	24.7	13.2	65.2	18.9	14.9

区域-月明细报表
区域	2016-01			2016-02
	电费	水费	燃气费	电费	水费	燃气费
江夏区	2240.9	330	425	5167	264.5	177.9
洪山区	576.7	264.7	173.2	665.2	108.9	184.9

区域月份-户明细报表
区域	月份	张三			李四
		燃气费	电费	水费	燃气费	电费	水费
江夏区	2016-01	2240.9	330	425	5167	264.5	177.9
洪山区	2016-01	576.7	264.7	173.2	665.2	108.9	184.9
江夏区	2016-02	3240.9	430	525	6167	364.5	277.9
洪山区	2016-02	676.7	364.7	273.2	765.2	208.9	284.9

  

  现在后台查出来的数据是List<House>类型，前台传过来分组维度和动态列字段。

  第1个表格前台传给后台参数

{DimensionList:['Name'],DynamicColumn:'Month'}

 第2个表格前台传给后台参数

{DimensionList:['Area'],DynamicColumn:'Month'}

第3个表格前台传给后台参数

{DimensionList:['Area','Month'],DynamicColumn:'Name'}

问题描述清楚后，仔细分析后你就会发现这里的难题在于动态分组，也就是怎么根据前台传过来的多个维度对List进行分组。

 

 

动态Linq

   下面使用System.Linq.Dynamic完成行转列功能，Nuget上搜索System.Linq.Dynamic即可下载该包。

   代码进行了封装，实现了通用的List<T>行转列功能。

        /// <summary>
        /// 动态Linq方式实现行转列
        /// </summary>
        /// <param name="list">数据</param>
        /// <param name="DimensionList">维度列</param>
        /// <param name="DynamicColumn">动态列</param>
        /// <returns>行转列后数据</returns>
        private static List<dynamic> DynamicLinq<T>(List<T> list, List<string> DimensionList, string DynamicColumn, out List<string> AllDynamicColumn) where T : class
        {
            //获取所有动态列
            var columnGroup = list.GroupBy(DynamicColumn, "new(it as Vm)") as IEnumerable<IGrouping<dynamic, dynamic>>;
            List<string> AllColumnList = new List<string>();
            foreach (var item in columnGroup)
            {
                if (!string.IsNullOrEmpty(item.Key))
                {
                    AllColumnList.Add(item.Key);
                }
            }
            AllDynamicColumn = AllColumnList;
            var dictFunc = new Dictionary<string, Func<T, bool>>();
            foreach (var column in AllColumnList)
            {
                var func = DynamicExpression.ParseLambda<T, bool>(string.Format("{0}=="{1}"", DynamicColumn, column)).Compile();
                dictFunc[column] = func;
            }

            //获取实体所有属性
            Dictionary<string, PropertyInfo> PropertyInfoDict = new Dictionary<string, PropertyInfo>();
            Type type = typeof(T);
            var propertyInfos = type.GetProperties(BindingFlags.Instance | BindingFlags.Public);
            //数值列
            List<string> AllNumberField = new List<string>();
            foreach (var item in propertyInfos)
            {
                PropertyInfoDict[item.Name] = item;
                if (item.PropertyType == typeof(int) || item.PropertyType == typeof(double) || item.PropertyType == typeof(float))
                {
                    AllNumberField.Add(item.Name);
                }
            }

            //分组
            var dataGroup = list.GroupBy(string.Format("new ({0})", string.Join(",", DimensionList)), "new(it as Vm)") as IEnumerable<IGrouping<dynamic, dynamic>>;
            List<dynamic> listResult = new List<dynamic>();
            IDictionary<string, object> itemObj = null;
            T vm2 = default(T);
            foreach (var group in dataGroup)
            {
                itemObj = new ExpandoObject();
                var listVm = group.Select(e => e.Vm as T).ToList();
                //维度列赋值
                vm2 = listVm.FirstOrDefault();
                foreach (var key in DimensionList)
                {
                    itemObj[key] = PropertyInfoDict[key].GetValue(vm2);
                }

                foreach (var column in AllColumnList)
                {
                    vm2 = listVm.FirstOrDefault(dictFunc[column]);
                    if (vm2 != null)
                    {
                        foreach (string name in AllNumberField)
                        {
                            itemObj[name + column] = PropertyInfoDict[name].GetValue(vm2);
                        }
                    }
                }
                listResult.Add(itemObj);
            }
            return listResult;
        }

   

   标红部分使用了System.Linq.Dynamic动态分组功能，传入字符串即可分组。使用了dynamic类型，关于dynamic介绍可以参考其它文章介绍哦。

回到顶部

System.Linq.Dynamic其它用法

    上面行转列代码见识了System.Linq.Dynamic的强大，下面再介绍一下会在开发中用到的方法。

    Where过滤

list.Where("Name=@0", "张三")

上面用到了参数化查询，实现了查找姓名是张三的数据，通过这段代码你或许感受不到它的好处。但是和EntityFramework结合起来就可以实现动态拼接SQL的功能了。

        /// <summary>
        /// EF实体查询封装 
        /// </summary>
        /// <typeparam name="T">实体类型</typeparam>
        /// <param name="Query">IQueryable对象</param>
        /// <param name="gridParam">过滤条件</param>
        /// <returns>查询结果</returns>
        public static EFPaginationResult<T> PageQuery<T>(this IQueryable<T> Query, QueryCondition gridParam)
        {
            //查询条件
            EFFilter filter = GetParameterSQL<T>(gridParam);
            var query = Query.Where(filter.Filter, filter.ListArgs.ToArray());
            //查询结果
            EFPaginationResult<T> result = new EFPaginationResult<T>();
            if (gridParam.IsPagination)
            {
                int PageSize = gridParam.PageSize;
                int PageIndex = gridParam.PageIndex < 0 ? 0 : gridParam.PageIndex;
                //获取排序信息
                string sort = GetSort(gridParam, typeof(T).FullName);
                result.Data = query.OrderBy(sort).Skip(PageIndex * PageSize).Take(PageSize).ToList<T>();
                if (gridParam.IsCalcTotal)
                {
                    result.Total = query.Count();
                    result.TotalPage = Convert.ToInt32(Math.Ceiling(result.Total * 1.0 / PageSize));
                }
                else
                {
                    result.Total = result.Data.Count();
                }
            }
            else
            {
                result.Data = query.ToList();
                result.Total = result.Data.Count();
            }
            return result;
        }

        /// <summary>
        /// 通过查询条件,获取参数化查询SQL
        /// </summary>
        /// <param name="gridParam">过滤条件</param>
        /// <returns>过滤条件字符</returns>
        private static EFFilter GetParameterSQL<T>(QueryCondition gridParam)
        {
            EFFilter result = new EFFilter();
            //参数值集合
            List<object> listArgs = new List<object>();
            string filter = "1=1";

            #region "处理动态过滤条件"
            if (gridParam.FilterList != null && gridParam.FilterList.Count > 0)
            {
                StringBuilder sb = new StringBuilder();

                int paramCount = 0;
                DateTime dateTime;
                //操作符
                string strOperator = string.Empty;
                foreach (var item in gridParam.FilterList)
                {
                    //字段名称为空则跳过
                    if (string.IsNullOrEmpty(item.FieldName))
                    {
                        continue;
                    }
                    //匹配枚举，防止SQL注入
                    Operator operatorEnum = (Operator)Enum.Parse(typeof(Operator), item.Operator, true);

                    //跳过字段值为空的
                    if (operatorEnum != Operator.Null && operatorEnum != Operator.NotNull && string.IsNullOrEmpty(item.FieldValue))
                    {
                        continue;
                    }
                    strOperator = operatorEnum.GetDescription();
                    if (item.IgnoreCase && !item.IsDateTime)
                    {
                        //2016-07-19添加查询时忽略大小写比较
                        item.FieldValue = item.FieldValue.ToLower();
                        item.FieldName = string.Format("{0}.ToLower()", item.FieldName);
                    }
                    switch (operatorEnum)
                    {
                        //等于,不等于，小于，大于，小于等于，大于等于
                        case Operator.EQ:
                        case Operator.NE:
                        case Operator.GT:
                        case Operator.GE:
                        case Operator.LT:
                        case Operator.LE:
                            if (item.IsDateTime)
                            {
                                if (DateTime.TryParse(item.FieldValue, out dateTime))
                                {
                                    if (!item.FieldValue.Contains("00:00:00") && dateTime.ToString("HH:mm:ss") == "00:00:00")
                                    {
                                        if (operatorEnum == Operator.LE)
                                        {
                                            listArgs.Add(DateTime.Parse(dateTime.ToString("yyyy-MM-dd") + " 23:59:59"));
                                        }
                                        else
                                        {
                                            listArgs.Add(dateTime);
                                        }
                                    }
                                    else
                                    {
                                        listArgs.Add(dateTime);
                                    }
                                    sb.AppendFormat(" AND {0} {1} @{2}", item.FieldName, strOperator, paramCount);
                                }
                            }
                            else
                            {
                                listArgs.Add(ConvertToType(item.FieldValue, GetPropType<T>(item.FieldName)));
                                sb.AppendFormat(" AND {0} {1} @{2}", item.FieldName, strOperator, paramCount);
                            }
                            paramCount++;
                            break;
                        case Operator.Like:
                        case Operator.NotLike:
                        case Operator.LLike:
                        case Operator.RLike:
                            listArgs.Add(item.FieldValue);
                            if (operatorEnum == Operator.Like)
                            {
                                sb.AppendFormat(" AND {0}.Contains(@{1})", item.FieldName, paramCount);
                            }
                            else if (operatorEnum == Operator.NotLike)
                            {
                                sb.AppendFormat(" AND !{0}.Contains(@{1})", item.FieldName, paramCount);
                            }
                            else if (operatorEnum == Operator.LLike)
                            {
                                sb.AppendFormat(" AND {0}.EndsWith(@{1})", item.FieldName, paramCount);
                            }
                            else if (operatorEnum == Operator.RLike)
                            {
                                sb.AppendFormat(" AND {0}.StartsWith(@{1})", item.FieldName, paramCount);
                            }
                            paramCount++;
                            break;
                        case Operator.Null:
                            listArgs.Add(item.FieldValue);
                            sb.AppendFormat(" AND {0}=null", item.FieldName);
                            paramCount++;
                            break;
                        case Operator.NotNull:
                            listArgs.Add(item.FieldValue);
                            sb.AppendFormat(" AND {0}!=null", item.FieldName);
                            paramCount++;
                            break;
                        case Operator.In:
                            sb.AppendFormat(" AND (");
                            foreach (var schar in item.FieldValue.Split(','))
                            {
                                listArgs.Add(schar);
                                sb.AppendFormat("{0}=@{1} or ", item.FieldName, paramCount);
                                paramCount++;
                            }
                            sb.Remove(sb.Length - 3, 3);
                            sb.AppendFormat(" )");
                            break;
                        case Operator.NotIn:
                            sb.AppendFormat(" AND (");
                            foreach (var schar in item.FieldValue.Split(','))
                            {
                                listArgs.Add(schar);
                                sb.AppendFormat("{0}!=@{1} and ", item.FieldName, paramCount);
                                paramCount++;
                            }
                            sb.Remove(sb.Length - 3, 3);
                            sb.AppendFormat(" )");
                            break;
                    }
                    if (sb.ToString().Length > 0)
                    {
                        filter = sb.ToString().Substring(4, sb.Length - 4);
                    }
                }
                #endregion

            }
            result.Filter = filter;
            result.ListArgs = listArgs;
            return result;
        }