C# 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。 阅读目录
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; } }
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
第2个表格前台传给后台参数
第3个表格前台传给后台参数
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)),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。 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
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}",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})",paramCount); } else if (operatorEnum == Operator.NotLike) { sb.AppendFormat(" AND !{0}.Contains(@{1})",paramCount); } else if (operatorEnum == Operator.LLike) { sb.AppendFormat(" AND {0}.EndsWith(@{1})",paramCount); } else if (operatorEnum == Operator.RLike) { sb.AppendFormat(" AND {0}.StartsWith(@{1})",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 ",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 ",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; } 总结 本篇通过行转列引出了System.Linq.Dynamic,并且介绍了过滤功能,其实它的用处还有很多,等待大家发掘。下面给出本文示例代码:DynamicLinq 以上就是本文的全部内容,希望本文的内容对大家的学习或者工作能带来一定的帮助,同时也希望多多支持编程小技巧! (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |