feat: Enhance IDataReader export with DynamicColumnFirst and Custom Formatting Delegate (#700)

* Add DynamicColumnFirst in config;

* Handle DynamicColumnFirst value assign;
Modify DynamicColumns ignore case;

* Handle CustomFormatter logic;

Author: IcedMango

src/MiniExcel/Attributes/ExcelColumnAttribute.cs

@@ -57,6 +57,8 @@ public enum ColumnType { Value, Formula }
     public class DynamicExcelColumn : ExcelColumnAttribute
     {
         public string Key { get; set; }
+        
+        public Func<object, string> CustomFormatter { get; set; }
 
         public DynamicExcelColumn(string key)
         {

src/MiniExcel/IConfiguration.cs

@@ -10,5 +10,10 @@ public abstract class Configuration : IConfiguration
         public DynamicExcelColumn[] DynamicColumns { get; set; }
         public int BufferSize { get; set; } = 1024 * 512;
         public bool FastMode { get; set; } = false;
+        
+        /// <summary>
+        ///     When exporting using DataReader, the data not in DynamicColumn will be filtered.
+        /// </summary>
+        public bool DynamicColumnFirst { get; set; } = false;
     }
 }

src/MiniExcel/OpenXml/ExcelOpenXmlSheetWriter.Async.cs

@@ -117,8 +117,25 @@ private async Task GenerateSheetByIDataReaderAsync(MiniExcelAsyncStreamWriter wr
                 for (var i = 0; i < reader.FieldCount; i++)
                 {
                     var columnName = reader.GetName(i);
-                    var prop = GetColumnInfosFromDynamicConfiguration(columnName);
-                    props.Add(prop);
+
+                    if (!_configuration.DynamicColumnFirst)
+                    {
+                        var prop = GetColumnInfosFromDynamicConfiguration(columnName);
+                        props.Add(prop);
+                        continue;
+                    }
+
+                    if (_configuration
+                        .DynamicColumns
+                        .Any(a => string.Equals(
+                            a.Key,
+                            columnName,
+                            StringComparison.OrdinalIgnoreCase)))
+
+                    {
+                        var prop = GetColumnInfosFromDynamicConfiguration(columnName);
+                        props.Add(prop);
+                    }
                 }
                 maxColumnIndex = props.Count;
 
@@ -149,7 +166,18 @@ private async Task GenerateSheetByIDataReaderAsync(MiniExcelAsyncStreamWriter wr
                     var xIndex = 1;
                     for (int i = 0; i < fieldCount; i++)
                     {
-                        var cellValue = reader.GetValue(i);
+                        object cellValue;
+
+                        if (_configuration.DynamicColumnFirst)
+                        {
+                            var columnIndex = reader.GetOrdinal(props[i].Key.ToString());
+                            cellValue = reader.GetValue(columnIndex);
+                        }
+                        else
+                        {
+                            cellValue = reader.GetValue(i);
+                        }
+
                         await WriteCellAsync(writer, yIndex, xIndex, cellValue, props[i], widths);
                         xIndex++;
                     }
@@ -534,7 +562,21 @@ private async Task WriteCellAsync(MiniExcelAsyncStreamWriter writer, int rowInde
             var columnType = p.ExcelColumnType;
 
             /*Prefix and suffix blank space will lost after SaveAs #294*/
-            var preserveSpace = cellValue != null && (cellValue.StartsWith(" ", StringComparison.Ordinal) || cellValue.EndsWith(" ", StringComparison.Ordinal));
+            var preserveSpace = cellValue != null && (cellValue.StartsWith(" ", StringComparison.Ordinal) ||
+                                                      cellValue.EndsWith(" ", StringComparison.Ordinal));
+
+            if (p.CustomFormatter != null)
+            {
+                try
+                {
+                    cellValue = p.CustomFormatter(cellValue);
+                }
+                catch (Exception e)
+                {
+                    //ignored
+                }
+            }
+            
             await writer.WriteAsync(WorksheetXml.Cell(columnReference, dataType, styleIndex, cellValue, preserveSpace: preserveSpace, columnType: columnType));
             widthCollection?.AdjustWidth(cellIndex, cellValue);
         }

src/MiniExcel/OpenXml/ExcelOpenXmlSheetWriter.DefaultOpenXml.cs

@@ -192,7 +192,7 @@ private ExcelColumnInfo GetColumnInfosFromDynamicConfiguration(string columnName
             if (_configuration.DynamicColumns == null || _configuration.DynamicColumns.Length <= 0)
                 return prop;
 
-            var dynamicColumn = _configuration.DynamicColumns.SingleOrDefault(_ => _.Key == columnName);
+            var dynamicColumn = _configuration.DynamicColumns.SingleOrDefault(_ => string.Equals(_.Key , columnName,StringComparison.OrdinalIgnoreCase));
             if (dynamicColumn == null || dynamicColumn.Ignore)
             {
                 return prop;
@@ -203,6 +203,7 @@ private ExcelColumnInfo GetColumnInfosFromDynamicConfiguration(string columnName
             prop.ExcelColumnType = dynamicColumn.Type;
             prop.ExcelColumnIndex = dynamicColumn.Index;
             prop.ExcelColumnWidth = dynamicColumn.Width;
+            prop.CustomFormatter = dynamicColumn.CustomFormatter;
             //prop.ExcludeNullableType = item2[key]?.GetType();
 
             if (dynamicColumn.Format != null)

src/MiniExcel/OpenXml/ExcelOpenXmlSheetWriter.cs

@@ -570,6 +570,19 @@ private void WriteCell(MiniExcelStreamWriter writer, int rowIndex, int cellIndex
             var styleIndex = tuple.Item1; // https://learn.microsoft.com/en-us/dotnet/api/documentformat.openxml.spreadsheet.cell?view=openxml-3.0.1
             var dataType = tuple.Item2; // https://learn.microsoft.com/en-us/dotnet/api/documentformat.openxml.spreadsheet.cellvalues?view=openxml-3.0.1
             var cellValue = tuple.Item3;
+            
+            if (columnInfo?.CustomFormatter != null)
+            {
+                try
+                {
+                    cellValue = columnInfo.CustomFormatter(cellValue);
+                }
+                catch (Exception e)
+                {
+                    //ignored
+                }
+            }
+            
             var columnType = columnInfo?.ExcelColumnType ?? ColumnType.Value;
 
             /*Prefix and suffix blank space will lost after SaveAs #294*/

src/MiniExcel/Utils/CustomPropertyHelper.cs

@@ -25,6 +25,7 @@ internal class ExcelColumnInfo
         public bool ExcelIgnore { get; internal set; }
         public int ExcelFormatId { get; internal set; }
         public ColumnType ExcelColumnType { get; internal set; }
+        public Func<object, string> CustomFormatter { get; set; }
     }
 
     internal class ExcellSheetInfo
@@ -310,6 +311,7 @@ internal static void SetDictionaryColumnInfo(List<ExcelColumnInfo> _props, objec
                     isIgnore = dynamicColumn.Ignore;
                     p.ExcelColumnWidth = dynamicColumn.Width;
                     p.ExcelColumnType = dynamicColumn.Type;
+                    p.CustomFormatter = dynamicColumn.CustomFormatter;
                 }
             }
             if (!isIgnore)