Exceed

Exceed is a high-level stream-oriented library for generating Excel files, useful when generating spreadsheets from data sets large enough that they may exceed available memory—or the available memory that one wants to dedicate to building spreadsheets.

Installation

def deps do
  [
    {:exceed, "~> 0.1"}
  ]
end

Why a duck?

XLSX files are zip files containing numerous XML files following SpreadsheetML OpenXML schemas. High-level libraries already exist to generate XLSX files from Elixir, but do not handle streams—all content to be written to a spreadsheet must be held in memory until the spreadsheet is fully written.

Low-level libraries already exist to generate XLSX files from streams, but are so low level that one must know all the ins and outs of SpreasheetML, including positional ordering of files, tags, and attributes.

We wanted a library that hides the complexity of streaming to XML to zlib, and hides the complexity of OOXML.

Usage

XLSX streams are generated by initializing a workbook (with a creator name), adding worksheets, and then converting that to a stream.

stream =
  Exceed.Workbook.new("Creator Name")
  |> Exceed.Workbook.add_worksheet(
    Exceed.Worksheet.new("Sheet Name", ["Heading 1", "Heading 2"]
      [["Row 1 Cell 1", "Row 1 Cell 2"], ["Row 2 Cell 1", "Row 2 Cell 2"]])
  )
  |> Exceed.stream!()

stream
|> Stream.into(File.stream!("/tmp/workbook.xslx"))
|> Stream.run()

Worksheets may be initialized with lists of lists, or they may be initialized with a stream of data that maps to a list of cells.

rows =
  Stream.unfold(1, fn
    10_001 -> nil
    row_count -> {["Row #{row_count} Cell 1", "Row #{row_count} Cell 2"], row_count + 1}
  end)

Exceed.Worksheet.new("Sheet Name", ["Heading 1", "Heading 2"], rows)

Alternatives & References

This library is inspired by and learns from other great libraries. One might choose to use one of those in place of Exceed:

elixlsx - Provides fine-grained control over cells, but is not stream-oriented and thus requires that all source data and rows be retained in memory until the entire workbook is written.
xlsx_stream - Provides low-level constructs that may be combined to make an Excel file. Works nicely with streams. Requires that one know all the ins and outs of SpreadsheetML in order to make a valid file that Excel can parse.

Contributing

This library uses medic for its development workflow.

brew bundle

bin/dev/doctor
bin/dev/test
bin/dev/audit
bin/dev/update
bin/dev/shipit