Npoi.Mapper

var mapper = new Mapper("Book1.xlsx");
var objs1 = mapper.Take<SampleClass>("sheet2");

// You can take objects from the same sheet with different type.
var objs2 = mapper.Take<AnotherClass>("sheet2");

// Even you can use dynamic type.
// DateTime, double and string will be auto-detected for object properties.
// You will get a DateTime property only if the cell in Excel was formatted as a date, otherwise it will be a double.
var objs3 = mapper.Take<dynamic>("sheet1").ToList();
DateTime date = obj3[0].DateColumn;
double number = obj3[0].NumberColumn;
string text = obj3[0].AC; // If the column doesn't have a header name, Excel display name like "AC" will be populated.

//var objects = ...
var mapper = new Mapper();
mapper.Save("test.xlsx",  objects, "newSheet", overwrite: false);

var mapper = new Mapper("Book1.xlsx");
mapper.TrackObjects = true; // It's default true.
var objectInfos = mapper.Take<SampleClass>("sheet2"); // You can Take first then modify tracked objects.
var objectsDict = mapper.Objects; // Also you can directly access objects in a sheet by property.
mapper.Save("test.xlsx",  "sheet2");

var mapper = new Mapper("Book1.xlsx");
mapper.Put(products, "sheet1", true);
mapper.Put(orders, "sheet2", false);
mapper.Save("Book1.xlsx");

mapper.Map<SampleClass>("ColumnA", o => o.Property1)
    .Map<SampleClass>(1, o => o.Property2)
    .Ignore<SampleClass>(o => o.Property3)
    .UseLastNonBlankValue<SampleClass>(o => o.Property1)
    .Format<SampleClass>("yyyy/MM/dd", o => o.DateProperty)
    .DefaultResolverType = typeof (SampleColumnResolver);

    public class SampleClass
    {
        // Other properties...
        
        [Display(Name = "Display Name")]
        public string DisplayNameProperty { get; set; }
        
        [Column(1)]
        public string Property1 { get; set; }
        
        [Column("ColumnABC")]
        public string Property2 { get; set; }
        
        [Column(CustomFormat = "0%")]
        public double CustomFormatProperty { get; set; }
        
        [UseLastNonBlankValue]
        public string UseLastNonBlankValueAttributeProperty { get; set; }
        
        [Ignore]
        public string IgnoredAttributeProperty { get; set; }
    }

    mapper.Format<SampleClass>("yyyy/MM/dd", o => o.DateProperty)
          .Format<SampleClass>("0%", o => o.DoubleProperty);

    public class SampleClass
    {
        [Column(CustomFormat = "yyyy-MM-dd")]
        public DateTime DateTimeFormatProperty { get; set; }
        
        [Column(CustomFormat = "0%")]
        public double CustomFormatProperty { get; set; }
    }

    mapper.UseFormat(typeof(DateTime), "yyyy.MM.dd hh.mm.ss");

    mapper.Map(
                column => // column filter : Custom logic to determine whether or not to map and include an unmapped column.
                {
                    // Header value is either in string or double. Try convert by needs.

                    var index = column.Attribute.Index;

                    if ((index == 31 || index == 33) && column.HeaderValue is double)
                    {
                        // Assign back header value and use it from TryTake method.
                        column.HeaderValue = DateTime.FromOADate((double)column.HeaderValue);

                        return true;
                    }

                    return false;
                },
                (column, target) => // tryTake resolver : Custom logic to take cell value into target object.
                {
                    // Note: return false to indicate a failure; and that will increase error count.
                    if (column.HeaderValue == null || column.CurrentValue == null) return false;
                    if (!(column.HeaderValue is DateTime)) return false;

                    ((SampleClass)target).CollectionGenericProperty.Add(((DateTime)column.HeaderValue).ToLongDateString() + column.CurrentValue);

                    return true;
                },
                (column, source) => // tryPut resolver : Custom logic to put property value into cell.
                {
                    if (column.HeaderValue is double)
                    {
                        column.HeaderValue = DateTime.FromOADate((double)column.HeaderValue);
                    }

                    var s = ((DateTime)column.HeaderValue).ToLongDateString();

                    // Custom logic to set the cell value.
                    var sample = (SampleClass) source;
                    if (column.Attribute.Index == 31 && sample.CollectionGenericProperty.Count > 0)
                    {
                        column.CurrentValue = sample.CollectionGenericProperty?.ToList()[0].Remove(0, s.Length);
                    }
                    else if (column.Attribute.Index == 33 && sample.CollectionGenericProperty.Count > 1)
                    {
                        column.CurrentValue = sample.CollectionGenericProperty?.ToList()[1].Remove(0, s.Length);
                    }

                    return true;
                }
                );