sqlsugar的行专列提示未将对象引用设置到对象实力,也就是null 情况的解决方法

把开源内的方法扒过来 加断点调吧  

ToPivotList1 因其方法内参数有this IEnumerable<T> source ,这样在使用的时候是可以在原查询中tolist后边点出来的.

参数 columnSelector 是对象 行转成的扩列 , rowSelector 保留列  dataSelector  对应sum 也就是数值列.
调用方法:查询.ToList().ToPivotTable(it => it.行转列的字段, it => it.保留列的字段, its => its.Any() ? its.Sum(x => x.数值字段):0);
最终找到是扩列前 扩列的字段有空值.  怼给datagridview后不显示最终建议使用 ToPivotTable()参数都一样, 转换成datatable.datagridview 能直接认出来的.

 public static  class DataHelper
    {
        public static List<dynamic> ToPivotList1<T, TColumn, TRow, TData>(
                                                                        this IEnumerable<T> source,
                                                                        Func<T, TColumn> columnSelector,
                                                                        Expression<Func<T, TRow>> rowSelector,
                                                                        Func<IEnumerable<T>, TData> dataSelector)
        {

            var arr = new List<object>();
            var cols = new List<string>();
            var rowName = "";
            if (rowSelector.Body is MemberExpression)
                rowName = ((MemberExpression)rowSelector.Body).Member.Name;
            else
                rowName = "Group_" + string.Join("_", ((NewExpression)rowSelector.Body).Arguments.Select(it => it as MemberExpression).Select(it => it.Member.Name));
            var columns = source.Select(columnSelector).Distinct();

            cols = (new[] { rowName }).Concat(columns.Select(x => x?.ToString())).ToList();
            var rows = source.GroupBy(rowSelector.Compile())
                             .Select(rowGroup => new
                             {
                                 Key = rowGroup.Key,
                                 Values = columns.GroupJoin(
                                     rowGroup,
                                     c => c,
                                     r => columnSelector(r),
                                     (c, columnGroup) => dataSelector(columnGroup))
                             }).ToList();


            foreach (var row in rows)
            {
                var items = row.Values.Cast<object>().ToList();
                items.Insert(0, row.Key);
                var obj = GetAnonymousObject(cols, items);
                arr.Add(obj);
            }
            return arr.ToList();
        }        private static dynamic GetAnonymousObject(IEnumerable<string> columns, IEnumerable<object> values)
        {
            IDictionary<string, object> eo = new ExpandoObject() as IDictionary<string, object>;
            int i;
            for (i = 0; i < columns.Count(); i++)
            {
                eo.Add(columns.ElementAt<string>(i), values.ElementAt<object>(i));
            }
            return eo;
        }

    }