Elixlsx is a writer for the MS Excel OpenXML format (.xlsx).

Quick Overview

The write_to/2 function takes a Elixlsx.Workbook object and a filename. A Workbook is a collection of Elixlsx.Sheets with (currently only) a creation date.

See the example.exs file for usage instructions.

Hacking / Technical overview

XLSX stores potentially repeating values in databases, most notably sharedStrings.xml and styles.xml. In these databases, each element is assigned a unique ID which is then referenced later. IDs are consecutive and correspond to the (0-indexed) position in the database (except for number/date formattings, where the ID is explicitly given in the attribute and needs to be at least 164).

The sharedStrings database is built up using the Elixlsx.Compiler.StringDB module. Pre-compilation, all cells are folded over, producing the StringDB struct which assigns each string a unique ID. The StringDB is part of the Elixlsx.Compiler.WorkbookCompInfo struct, which is passed to the XML generating function, which then get_id's the ID associated with the string found in the cell.

For styles.xml, the procedure is in general the same, but slightly more complicated since elements can reference other elements in the same file. The Elixlsx.Style.CellStyle element is the combination of sub-styles (Elixlsx.Style.Font, Elixlsx.Style.NumFmt, ...). A call to register_all creates the (unique) entries in the sub-style databases (Elixlsx.Compiler.FontDB, Elixlsx.Compiler.NumFmtDB). Afterwards, each unique combination of substyles is assigned an ID in Elixlsx.Compiler.CellStyleDB. During XML generation, the <xf> elements reference the individual sub-style IDs, and the actual cell element references the <xf> id.