Bulk insert data

Inserting a larger amount of data can be done using IXLCell.InsertData methods. Methods will insert data to cells staring from the referenced cell.

There are several possible inputs. ClosedXML doesn’t add header for bulk data insert.


You can insert data directly from DataTable. This feature is useful if you work with ADO.NET.

var dataTable = new DataTable();
dataTable.Columns.Add("Name", typeof(string));
dataTable.Columns.Add("Sold", typeof(int));

dataTable.Rows.Add("Cheesecake", 14);
dataTable.Rows.Add("Medovik", 6);
dataTable.Rows.Add("Muffin", 10);

using var wb = new XLWorkbook();
var ws = wb.AddWorksheet();
Data inserted through code sample

Generic Enumerable

Insert data from a generic IEnumerable<>. The data inserted differ depending on the type of an item type of the IEnumerable<>.

A method used to insert the values from a generic IEnumerable<> is the IXLCell.InsertData(IEnumerable data), despite the parameter not being generic IEnumerable<>.

Structure of all items is determined by the generic parameter type.

Objects or structs

Items of the IEnumerable<> are an object or struct (e.g. DTO). All public fields and properties (instance or static), will be used as a source of data for columns. Members can be nullable and indexers are ignored.

The way members are processed can be modified by adding a XLColumnAttribute:

  • A member can be ignored through [XLColumn(Ignore = true)]

  • The order of members in a class is undefined. Use [XLColumn(Order=1)] to specify the order.

public record Dessert(
    [property:XLColumn(Ignore = true)] int SellerId,
    [property:XLColumn(Order = 1)] string Name,
    [property:XLColumn(Order = 2)] int Sales);

var data = new[] {
    new Dessert(1, "Cheesecake", 14),
    new Dessert(2, "Medovik", 6),
    new Dessert(2, "Muffin", 10),

using var wb = new XLWorkbook();
var ws = wb.AddWorksheet();


Items of IEnumerable<> is another type implementing IEnumerable (e.g. array or List). The items of the nested IEnumerable must be assignable to a cell.

var data = new List<object[]>
    new object[] { "Cheesecake", 14 },
    new object[] { "Medovik", 6 },
    new object[] { "Muffin", 10 }

using var wb = new XLWorkbook();
var ws = wb.AddWorksheet();


Items of IEnumerable<> implement interface System.Data.IDataRecord.

Simple type

Items of IEnumerable<> are a primitive type, string, DateTime, TimeSpan, or a number. Type of the items can also be nullable (e.g. int?).

Simple type items always inserts only one column.


Items of IEnumerable<> are a DataRow. ClosedXMl behaves like when inserting data from DataTable.

Untyped Enumerable

Mostly used for untyped collections, like ArrayList.

Types of items behave same way as for the generic enumerable.

ClosedXML can handle a case where each item is of different type.

public record Dessert(
    [property: XLColumn(Ignore = true)] int SellerId,
    [property: XLColumn(Order = 1)] string Name,
    [property: XLColumn(Order = 2)] int Sales);

var data = new ArrayList
    new object[] { "Cheesecake", 14 },
    new Dessert(1, "Medovik", 6),
    new object[] { "Muffin", 10 },

using var wb = new XLWorkbook();
var ws = wb.AddWorksheet();