CSV to XLSX File Conversion

Mix.install([
  {:kino, "~> 0.11.0"},
  {:elixlsx, "~> 0.5.1"}
])

Introduction

Excel is a poplular spreadsheet program that has its own interpretation of what a CSV file is.

This workbook allows you to upload a CSV file, choose a separator (string), and name the columns. It will then produce a xlsx file (aka an Excel file) and allow this to be downloaded.

Upload CSV File

filename_kino = Kino.Input.file("Upload CSV file:")

fileref = Kino.Input.read(filename_kino)
filename = Kino.Input.file_path(fileref.file_ref)

Explore Upload

Determine column separator:

sep_kino = Kino.Input.text("Column separator:", default: ",")

sep = Kino.Input.read(sep_kino)

First parsing phase:

input =
  filename
  |> File.read!()
  |> String.split("\n")
  |> Enum.map(&String.trim/1)
  |> Enum.map(fn line ->
    line
    |> String.split(sep)
  end)

Please name the columns:

col_count =
  input
  |> Enum.map(&length/1)
  |> Enum.reduce(&max/2)

col_elements =
  1..col_count
  |> Enum.map(fn col -> Kino.Input.text("Name column #{col}:", default: col) end)

form = Kino.Layout.grid(col_elements)

Convert to list of maps for easy displaying:

col2name =
  1..col_count
  |> Enum.map(fn col ->
    Kino.Input.read(Enum.at(col_elements, col - 1))
  end)

input =
  input
  |> Enum.map(fn entry ->
    entry
    |> Enum.with_index(fn value, index -> {Enum.at(col2name, index), value} end)
    |> Map.new()
  end)

# |> Enum.take(100)

Now, we can display the data on tabular format:

Kino.DataTable.new(input)

Generate Excel Sheets

defmodule Sheet do
  alias Elixlsx.{Sheet}

  def produce_csv(sheet, input, col2name) do
    sheet
    |> Sheet.set_cell("A1", "CSV to Excel Conversion", bold: true, italic: true)
    |> Sheet.set_row_height(1, 16)
    |> Sheet.set_row_height(2, 2)
    |> add_header(col2name)
    |> add_data(col2name, input)
  end

  defp add_header(sheet, col2name) do
    col2name
    |> Enum.with_index(fn name, col -> {col, name} end)
    |> List.foldl(sheet, fn {col, name}, sheet ->
      cell = cellname(col, 3)
      Sheet.set_cell(sheet, cell, name, bold: true)
    end)
  end

  defp add_data(sheet, col2name, input) do
    input
    |> List.foldl({sheet, 4}, fn entry, {sheet, row} ->
      sheet =
        col2name
        |> Enum.with_index(fn name, col -> {col, name} end)
        |> List.foldl(sheet, fn {col, name}, sheet ->
          cell = cellname(col, row)
          value = Map.get(entry, name)
          Sheet.set_cell(sheet, cell, value)
        end)

      {sheet, row + 1}
    end)
    |> elem(0)
  end

  defp cellname(col, row) do
    map =
      "A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z"
      |> String.split(",")

    "#{Enum.fetch!(map, col)}#{row}"
  end
end

sheets = [
  Elixlsx.Sheet.with_name("Contents")
  |> Sheet.produce_csv(input, col2name)
]

Present Download Option

filename = "converted.xlsx"

file_producer = fn ->
  {:ok, {_filename, contents}} =
    %Elixlsx.Workbook{sheets: sheets}
    |> Elixlsx.write_to_memory(filename)

  contents
end

Kino.Download.new(file_producer, filename: filename)