C# List實現行轉列的通用方案。本站提示廣大學習愛好者：（C# List實現行轉列的通用方案）文章只能為提供參考，不一定能成為您想要的結果。以下是C# List實現行轉列的通用方案正文
最近在做報表統計方面的需求，涉及到行轉列報表。根據以往經驗使用SQL可以比較容易完成，這次決定挑戰一下直接通過代碼方式完成行轉列。期間遇到幾個問題和用到的新知識這裡整理記錄一下。
閱讀目錄
問題介紹 動態Linq System.Linq.Dynamic其它用法 總結問題介紹
以家庭月度費用為例，可以在[Name,Area,Month]三個維度上隨意組合進行分組，三個維度中選擇一個做為列顯示。
/// <summary>
/// 家庭費用情況
/// </summary>
public class House
{
/// <summary>
/// 戶主姓名
/// </summary>
public string Name { get; set; }
/// <summary>
/// 所屬行政區域
/// </summary>
public string Area { get; set; }
/// <summary>
/// 月份
/// </summary>
public string Month { get; set; }
/// <summary>
/// 電費金額
/// </summary>
public double DfMoney { get; set; }
/// <summary>
/// 水費金額
/// </summary>
public double SfMoney { get; set; }
/// <summary>
/// 燃氣金額
/// </summary>
public double RqfMoney { get; set; }
}
戶主-月明細報表
區域-月明細報表
區域月份-戶明細報表
現在後台查出來的數據是List<House>類型，前台傳過來分組維度和動態列字段。
第1個表格前台傳給後台參數
{DimensionList:['Name'],DynamicColumn:'Month'}
第2個表格前台傳給後台參數
{DimensionList:['Area'],DynamicColumn:'Month'}
第3個表格前台傳給後台參數
{DimensionList:['Area','Month'],DynamicColumn:'Name'}
問題描述清楚後，仔細分析後你就會發現這裡的難題在於動態分組，也就是怎麼根據前台傳過來的多個維度對List進行分組。
動態Linq
下面使用System.Linq.Dynamic完成行轉列功能，Nuget上搜索System.Linq.Dynamic即可下載該包。
代碼進行了封裝，實現了通用的List<T>行轉列功能。
/// <summary>
/// 動態Linq方式實現行轉列
/// </summary>
/// <param name="list">數據</param>
/// <param name="DimensionList">維度列</param>
/// <param name="DynamicColumn">動態列</param>
/// <returns>行轉列後數據</returns>
private static List<dynamic> DynamicLinq<T>(List<T> list, List<string> DimensionList, string DynamicColumn, out List<string> AllDynamicColumn) where T : class
{
//獲取所有動態列
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;
}
//獲取實體所有屬性
Dictionary<string, PropertyInfo> PropertyInfoDict = new Dictionary<string, PropertyInfo>();
Type type = typeof(T);
var propertyInfos = type.GetProperties(BindingFlags.Instance | BindingFlags.Public);
//數值列
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);
}
}
//分組
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();
//維度列賦值
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;
}
標紅部分使用了System.Linq.Dynamic動態分組功能，傳入字符串即可分組。使用了dynamic類型，關於dynamic介紹可以參考其它文章介紹哦。
System.Linq.Dynamic其它用法
上面行轉列代碼見識了System.Linq.Dynamic的強大，下面再介紹一下會在開發中用到的方法。
Where過濾
list.Where("Name=@0", "張三")
上面用到了參數化查詢，實現了查找姓名是張三的數據，通過這段代碼你或許感受不到它的好處。但是和EntityFramework結合起來就可以實現動態拼接SQL的功能了。
/// <summary>
/// EF實體查詢封裝
/// </summary>
/// <typeparam name="T">實體類型</typeparam>
/// <param name="Query">IQueryable對象</param>
/// <param name="gridParam">過濾條件</param>
/// <returns>查詢結果</returns>
public static EFPaginationResult<T> PageQuery<T>(this IQueryable<T> Query, QueryCondition gridParam)
{
//查詢條件
EFFilter filter = GetParameterSQL<T>(gridParam);
var query = Query.Where(filter.Filter, filter.ListArgs.ToArray());
//查詢結果
EFPaginationResult<T> result = new EFPaginationResult<T>();
if (gridParam.IsPagination)
{
int PageSize = gridParam.PageSize;
int PageIndex = gridParam.PageIndex < 0 ? 0 : gridParam.PageIndex;
//獲取排序信息
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>
/// 通過查詢條件,獲取參數化查詢SQL
/// </summary>
/// <param name="gridParam">過濾條件</param>
/// <returns>過濾條件字符</returns>
private static EFFilter GetParameterSQL<T>(QueryCondition gridParam)
{
EFFilter result = new EFFilter();
//參數值集合
List<object> listArgs = new List<object>();
string filter = "1=1";
#region "處理動態過濾條件"
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)
{
//字段名稱為空則跳過
if (string.IsNullOrEmpty(item.FieldName))
{
continue;
}
//匹配枚舉，防止SQL注入
Operator operatorEnum = (Operator)Enum.Parse(typeof(Operator), item.Operator, true);
//跳過字段值為空的
if (operatorEnum != Operator.Null && operatorEnum != Operator.NotNull && string.IsNullOrEmpty(item.FieldValue))
{
continue;
}
strOperator = operatorEnum.GetDescription();
if (item.IgnoreCase && !item.IsDateTime)
{
//2016-07-19添加查詢時忽略大小寫比較
item.FieldValue = item.FieldValue.ToLower();
item.FieldName = string.Format("{0}.ToLower()", item.FieldName);
}
switch (operatorEnum)
{
//等於,不等於，小於，大於，小於等於，大於等於
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;
}
總結
本篇通過行轉列引出了System.Linq.Dynamic，並且介紹了過濾功能，其實它的用處還有很多，等待大家發掘。下面給出本文示例代碼：DynamicLinq
以上就是本文的全部內容，希望本文的內容對大家的學習或者工作能帶來一定的幫助，同時也希望多多支持！
[db:作者簡介][db:原文翻譯及解析]
