ExcelORM/ExcelORM/ExcelORM/ExcelDynamicReader.cs

using ClosedXML.Excel;
using ExcelORM.Models;

namespace ExcelORM;

public class ExcelDynamicReader
{
    private readonly IXLWorkbook xlWorkbook;
    public bool SkipHidden { get; set; }
    public bool ObeyFilter { get; set; }

    public ExcelDynamicReader(string? path)
    {
        xlWorkbook = new XLWorkbook(path);
    }

    private IEnumerable<List<DynamicCell>> ProcessRows(IEnumerable<IXLRow> rows, List<DynamicCell> mapping)
    {
        foreach (var row in rows)
        {
            if (SkipHidden && row.IsHidden) continue;

            var dynamicRow = new List<DynamicCell>();
            foreach (var item in mapping)
            {
                var cell = row.Cell(item.Position);
                if (cell == null || cell.Value.IsBlank) continue;

                if (item.Type == null) item.Type = cell.Value.ValueType();

                var cellItem = item with
                {
                    Value = cell.Value.ToObject()
                };

                dynamicRow.Add(cellItem);
            }

            yield return dynamicRow;
        }
    }

    public IEnumerable<List<DynamicCell>> Read(string? worksheetName, uint startFrom = 1, uint skip = 0)
    {
        var worksheet = xlWorkbook.Worksheets.FirstOrDefault(x => x.Name.Equals(worksheetName, StringComparison.InvariantCultureIgnoreCase));
        if (worksheet == null) yield break;

        var firstRow = worksheet.Row((int)startFrom);
        if (firstRow.IsEmpty())
            firstRow = worksheet.RowsUsed().First(x => x.RowNumber() > startFrom && !x.IsEmpty());
        
        var mapping = DynamicCell.MapHeader(firstRow.CellsUsed());
        if (mapping == null || mapping.Count == 0) yield break;

        var rowsToProcess = (ObeyFilter && worksheet.AutoFilter.IsEnabled) switch
        {
            true => worksheet.AutoFilter.VisibleRows
                .Where(x => x.RowNumber() > firstRow.RowNumber())
                .Select(x => x.WorksheetRow()),
            false => worksheet.RowsUsed().Where(x => x.RowNumber() > firstRow.RowNumber())
                
        };

        rowsToProcess = rowsToProcess
            .Skip((int)skip);
        
        foreach (var item in ProcessRows(rowsToProcess, mapping))
            yield return item;
    } 
}