Devexpress Office File Api Excel Export

DevExpress Excel Export Library

The Excel Export Library is a low-level, streaming .NET API for generating Excel files (.xlsx, .xls, .csv) with a minimal memory footprint. It writes rows sequentially to an output stream and cannot read or modify existing files. Use it when you need to produce large Excel reports from databases or data grids without loading the entire document into RAM. The primary namespace is DevExpress.Export.Xl.

CRITICAL: Excel Export Library vs. Spreadsheet Document API

| | Excel Export Library | Spreadsheet Document API | |---|---|---| | Model | Streaming — write rows top-to-bottom, forward only | In-memory — random access to any cell at any time | | Memory | Very low — ideal for large files | Higher — entire workbook in RAM | | Can read files? | No | Yes | | Can modify existing files? | No | Yes | | Charts, Pivot Tables? | No | Yes | | NuGet | DevExpress.Document.Processor (shared) | DevExpress.Document.Processor | | Namespace | DevExpress.Export.Xl | DevExpress.Spreadsheet |

Rule: If the developer needs to read, modify, add charts, or create pivot tables → use the Spreadsheet Document API skill instead. If they need to stream-generate a large file from data → this skill is correct.

When to Use This Skill

Use this skill when you need to:

• Generate large Excel reports (.xlsx) with low memory consumption
• Write rows sequentially from a database reader or IEnumerable data source
• Export grid or report engine data to Excel in a streaming fashion
• Create Excel files in server-side or cloud environments where RAM is constrained
• Apply cell formatting (fonts, colors, borders, number formats) during export
• Add formulas, subtotals, or AutoFilter to generated files
• Create conditional formatting rules on streamed data
• Build Excel tables (IXlTable) with styles and calculated columns
• Insert sparklines or pictures into generated worksheets
• Configure print settings, headers/footers, and page breaks
• Add data validation rules to cell ranges

Prerequisites & Installation

NuGet Packages

| Package | Purpose | |---------|---------| | DevExpress.Document.Processor | Excel Export Library (streaming API) |

String formulas (parsed from text) require an additional reference — see [references/getting-started.md](references/getting-started.md).

.NET (6/7/8+)

dotnet add package DevExpress.Document.Processor

.NET Framework (4.6.2+)

Add assembly references manually — see [references/getting-started-dotnet-fw.md](references/getting-started-dotnet-fw.md).

Important: All DevExpress packages in a project must share the same version number. A valid DevExpress license is required.

Before You Start — Ask the Developer

Before generating code, ask these questions to avoid rework:

General Questions

1. Target framework: Are you using .NET 8+, .NET 6/7, or .NET Framework 4.x?
2. New or existing project?: Are you creating a new project or adding to an existing one?
3. Hosting model: Console app, ASP.NET Core, Blazor, MAUI, WinForms, WPF, or something else?

Excel Export-Specific Questions

1. Scenario check: Are you generating a new large report (this library is correct) or do you need to read/modify an existing file (use Spreadsheet Document API instead)?
2. Data source: IEnumerable / DataTable / direct row-by-row writing / database reader?
3. Excel features beyond basic cells: formulas / tables / conditional formatting / sparklines / pictures / printing?

> Rule: If the developer's answer is ambiguous or missing, ask before generating code. Do not guess.

Component Overview

The Excel Export Library provides:

• Exporter factory: Create an exporter targeting XLSX, XLS, or CSV (XlExport, IXlExporter)
• Document and sheet management: Create documents and worksheets sequentially (IXlDocument, IXlSheet)
• Row and column writing: Stream rows and configure columns (IXlRow, IXlColumn)
• Cell authoring: Set values (string, number, bool, date, error), formulas, and formatting (IXlCell, XlCellFormatting)
• Advanced worksheet features: Conditional formatting, tables, sparklines, pictures, data validation, print settings

Core Entry Point

using DevExpress.Export.Xl;
using System.IO;

// Step 1: create an exporter for the target format
IXlExporter exporter = XlExport.CreateExporter(XlDocumentFormat.Xlsx);

// Step 2: open a stream and create the document
using (FileStream stream = new FileStream("output.xlsx", FileMode.Create, FileAccess.ReadWrite))
using (IXlDocument document = exporter.CreateDocument(stream))
{
    // Step 3: create a sheet
    using (IXlSheet sheet = document.CreateSheet())
    {
        sheet.Name = "Report";

        // Step 4: write rows top-to-bottom
        using (IXlRow row = sheet.CreateRow())
        using (IXlCell cell = row.CreateCell())
        {
            cell.Value = "Hello, World!";
        }
    }
} // document is finalized and flushed here

Documentation & Navigation Guide

Getting Started (.NET)

Refer to [references/getting-started.md](references/getting-started.md)

When you need to:

• Install NuGet packages and set up a .NET project
• Understand the streaming document model
• Create your first XLSX file end-to-end
• Use string formulas (requires XlFormulaParser)
• See a complete working example with headers and data rows

Getting Started (.NET Framework)

Refer to [references/getting-started-dotnet-fw.md](references/getting-started-dotnet-fw.md)

When you need to:

• Set up a .NET Framework 4.6.2+ project with assembly references
• Understand which DLLs are required
• Handle framework-specific API differences

Cells and Formatting

Refer to [references/cells-and-formatting.md](references/cells-and-formatting.md)

When you need to:

• Create cells and set values (string, numeric, bool, date, error)
• Apply fonts, colors, background fills, and borders
• Set number formats (currency, date, percentage, custom)
• Align cell content (horizontal, vertical, wrap, indent)
• Apply predefined or theme-based cell styles
• Create rich text (mixed fonts within a single cell)
• Merge cells or add hyperlinks
• Apply conditional formatting rules

Advanced Features

Refer to [references/advanced-features.md](references/advanced-features.md)

When you need to:

• Create Excel tables (IXlTable) with styles and calculated columns
• Add string, expression, or token-based cell formulas
• Create shared formulas or SUBTOTAL aggregations
• Add sparklines (line, column, win/loss) and customize them
• Insert pictures and add hyperlinks to pictures
• Configure print settings, page margins, headers/footers, page breaks, print titles
• Group rows or columns
• Enable AutoFilter on a data range
• Add data validation rules

Quick Start Example

using DevExpress.Export.Xl;
using System.IO;

IXlExporter exporter = XlExport.CreateExporter(XlDocumentFormat.Xlsx);

using (FileStream stream = new FileStream("SalesReport.xlsx", FileMode.Create, FileAccess.ReadWrite))
using (IXlDocument document = exporter.CreateDocument(stream))
{
    using (IXlSheet sheet = document.CreateSheet())
    {
        sheet.Name = "Sales";

        // Freeze header row
        sheet.SplitPosition = new XlCellPosition(0, 1);

        // Header formatting
        XlCellFormatting headerFmt = new XlCellFormatting();
        headerFmt.Font = new XlFont { Bold = true };
        headerFmt.Font.Color = XlColor.FromTheme(XlThemeColor.Light1, 0.0);
        headerFmt.Fill = XlFill.SolidFill(XlColor.FromTheme(XlThemeColor.Accent1, 0.0));

        // Write header row
        string[] headers = { "Product", "Q1", "Q2", "Total" };
        using (IXlRow row = sheet.CreateRow())
        {
            foreach (string h in headers)
            {
                using (IXlCell cell = row.CreateCell())
                {
                    cell.Value = h;
                    cell.ApplyFormatting(headerFmt);
                }
            }
        }

        // Write 3 data rows
        string[] products = { "Widget A", "Widget B", "Widget C" };
        int[] q1 = { 12000, 8500, 15000 };
        int[] q2 = { 14500, 9200, 11000 };

        for (int i = 0; i < 3; i++)
        {
            using (IXlRow row = sheet.CreateRow())
            {
                using (IXlCell cell = row.CreateCell()) { cell.Value = products[i]; }
                using (IXlCell cell = row.CreateCell()) { cell.Value = q1[i]; }
                using (IXlCell cell = row.CreateCell()) { cell.Value = q2[i]; }
                using (IXlCell cell = row.CreateCell())
                {
                    // Formula: =B{row}+C{row}
                    int rowNum = i + 2;
                    cell.SetFormula($"=B{rowNum}+C{rowNum}");
                }
            }
        }

        // Enable AutoFilter
        sheet.AutoFilterRange = sheet.DataRange;
    }
}

What This Does

Creates SalesReport.xlsx with a styled header row (bold, theme-colored), three data rows with numeric Q1/Q2 values, a formula-driven Total column, a frozen header row, and AutoFilter enabled. No Microsoft Office is required.

Key Properties & API Surface

XlExport (static entry point)

| Method | Return Type | Description | |--------|-------------|-------------| | CreateExporter(XlDocumentFormat) | IXlExporter | Create an exporter for XLSX, XLS, or CSV | | CreateExporter(XlDocumentFormat, XlFormulaParser) | IXlExporter | Create with string formula parsing support |

IXlExporter

| Method | Return Type | Description | |--------|-------------|-------------| | CreateDocument(Stream) | IXlDocument | Begin writing a new document to the stream |

IXlDocument

| Property/Method | Type | Description | |----------------|------|-------------| | CreateSheet() | IXlSheet | Add and begin writing a new worksheet | | Options | IDataAwareExporterOptions | Culture, encoding, and format options | | Theme | XlDocumentTheme | Active document theme (default: Office 2013) |

IXlSheet

| Property/Method | Type | Description | |----------------|------|-------------| | CreateRow() | IXlRow | Append and begin writing the next row | | CreateColumn() | IXlColumn | Define the next column (call before rows) | | Name | string | Worksheet tab name | | SplitPosition | XlCellPosition | Freeze panes anchor (set before rows/columns) | | AutoFilterRange | XlCellRange | Range where AutoFilter is applied | | DataRange | XlCellRange | Range of all data written so far | | Visible | bool | Show or hide the worksheet tab | | PrintOptions | XlPrintOptions | Print-related settings | | PageSetup | XlPageSetup | Page orientation, paper size, scaling | | PageMargins | XlPageMargins | Margin settings for printing | | HeaderFooter | XlHeaderFooter | Headers and footers for printed pages | | PrintTitles | XlPrintTitles | Rows/columns repeated on each printed page |

IXlRow

| Property/Method | Type | Description | |----------------|------|-------------| | CreateCell() | IXlCell | Append the next cell in this row | | CreateCell(int columnIndex) | IXlCell | Create a cell at a specific column index | | SkipCells(int count) | void | Skip columns (leave them empty) | | ApplyFormatting(XlCellFormatting) | void | Apply formatting to the entire row | | Formatting | XlCellFormatting | Row-level default formatting | | HeightInPixels | int | Row height in pixels | | IsHidden | bool | Hide the row | | RowIndex | int | Zero-based row index | | OutlineLevel | int | Grouping level (for row grouping) |

IXlColumn

| Property/Method | Type | Description | |----------------|------|-------------| | ApplyFormatting(XlCellFormatting) | void | Apply formatting to the entire column | | Formatting | XlCellFormatting | Column-level default formatting | | WidthInPixels | int | Column width in pixels | | WidthInCharacters | double | Column width in character units | | IsHidden | bool | Hide the column | | OutlineLevel | int | Grouping level (for column grouping) |

IXlCell

| Property/Method | Type | Description | |----------------|------|-------------| | Value | XlVariantValue | Cell value (string, number, bool, or error) | | Formatting | XlCellFormatting | Cell-level formatting | | ApplyFormatting(XlCellFormatting) | void | Apply a formatting object to this cell | | SetFormula(string) | void | Set formula from text (requires XlFormulaParser) | | SetFormula(IXlFormulaParameter) | void | Set formula from expression objects | | SetFormula(XlExpression) | void | Set formula from token list | | SetRichText(XlRichTextString) | void | Set rich-formatted text (multiple fonts) | | ColumnIndex | int | Zero-based column index of this cell |

XlCellFormatting

| Property | Type | Description | |----------|------|-------------| | Font | XlFont | Font settings (name, size, bold, italic, color) | | Fill | XlFill | Background fill (solid color or pattern) | | Alignment | XlCellAlignment | Horizontal/vertical alignment, wrap, indent | | Border | XlBorder | Border line styles and colors | | NumberFormat | string | Excel number format string |

Common Patterns

Pattern 1: Apply Formatting to an Entire Column

using (IXlColumn column = sheet.CreateColumn())
{
    column.WidthInPixels = 120;
    column.Formatting = new XlCellFormatting();
    column.Formatting.NumberFormat = "$#,##0.00";
}

Pattern 2: Skip to a Specific Column

using (IXlRow row = sheet.CreateRow())
{
    row.SkipCells(2); // leave columns A and B empty
    using (IXlCell cell = row.CreateCell()) // cell is in column C
    {
        cell.Value = "Starting at C";
    }
}

Pattern 3: Password-Protect the Workbook

using (IXlDocument document = exporter.CreateDocument(stream))
{
    document.Options.EncryptionOptions = new EncryptionOptions { Password = "MyPassword" };
    // ... create sheets and rows
}

Pattern 4: Subtotal Formula (no string parser needed)

using (IXlCell cell = row.CreateCell())
{
    // SUBTOTAL(9, C2:C10) — SUM ignoring hidden rows
    cell.SetFormula(XlFunc.Subtotal(
        XlCellRange.FromLTRB(2, 1, 2, 9),
        XlSummary.Sum,
        ignoreHiddenRows: true));
}

Troubleshooting

| Symptom | Cause | Solution | |---------|-------|----------| | InvalidOperationException when setting SplitPosition | Set after rows/columns were already created | Set sheet.SplitPosition as the first operation after CreateSheet() | | String formula throws NullReferenceException or is ignored | XlFormulaParser not supplied | Use XlExport.CreateExporter(format, new XlFormulaParser()) | | XlFormulaParser type not found | Missing assembly reference | Reference DevExpress.Spreadsheet.vXX.X.Core.dll (.NET FW) or ensure DevExpress.Document.Processor is installed (.NET) | | Cells appear out of order | Cells must be written left-to-right within a row | Use row.CreateCell(columnIndex) to skip ahead, or row.SkipCells(n) | | File is corrupt or truncated | IXlDocument or IXlExporter not disposed | Wrap all levels in using blocks; the document is finalized on Dispose() | | Version mismatch build error | Mixed DevExpress package versions | Ensure all DX packages use the exact same version (e.g., all 25.2.x) | | License error at runtime | Missing DevExpress license | Register license per installation guide; check license file deployment |

Constraints & Rules

CRITICAL — follow these rules in every interaction:

1. Streaming only: This API writes forward. You cannot go back to modify a previously written row or cell.
2. Dispose order matters: Dispose IXlCell before creating the next cell, IXlRow before the next row, IXlSheet before the next sheet, and IXlDocument to finalize the file.

…

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: DevExpress
• Source: DevExpress/agent-skills
• License: MIT
• Homepage: https://www.devexpress.com

Install and usage instructions live in the source repository linked above.