public ConvertToListOptions <T> MapColumn(string columnName, PropertyInfo propertyInfo, Delegate projection = null) { if (!ColumnMapper.ContainsKey(columnName)) { ColumnMapper.Add(columnName, propertyInfo); if (projection != null) { Projection.Add(columnName, projection); } return(this); } else { throw new MappingException("列名【" + columnName + "】重复配置"); } }