methods to create a markdown-formatted table from 2d-arrays, hashes or csv data

markdown_table.rb

require 'json'

def to_md_row(row, max_field_sizes)
  md = row.zip(max_field_sizes).map do |field, sz|
    "#{field.to_s.ljust(sz, ' ')}"
  end.join(' | ')
  "| #{md} |"
end

def table_def_row(max_field_sizes)
  table_def = max_field_sizes.map { |sz| ":#{'-' * (sz + 1)}"}.join('|')
  "|#{table_def}|"  
end

# @param name [String] table name
# @param fields [Array<Array<String>>] mxn 2d array to be converted to table.
#   First row is used as the header 
def to_table(fields, name = nil)
  table = name ? ["**#{name}**"] : []
  m = fields.size
  return table[0] unless m > 0

  n = fields[0].size
  return table[0] unless n > 0

  max_field_sizes = n.times.map{ |col| fields.map { |row| row[col].to_s.length }.max }
  table << to_md_row(fields.first, max_field_sizes)
  table << table_def_row(max_field_sizes)
  fields[1..-1].each do |row|
    table << to_md_row(row, max_field_sizes)
  end
  table.join("\n")
end


# @param json_string [String] String containing all results, e.g.
# [
#   {
#     "id": 1,
#     "name": "Meier",
#     "vorname": "Lena",
#     "adresse": "Heideweg 1",
#     "plz": 3000,
#     "gebdatum": "1996-02-16",
#     "lehrfirma": "Ascom",
#     "klassen_id": 1
#   },
#   {
#     "id": 2,
#     "name": "Zangger",
#     "vorname": "Eva",
#     "adresse": "Ahornweg 34",
#     "plz": 4002,
#     "gebdatum": "1998-08-23",
#     "lehrfirma": "Swisscom",
#     "klassen_id": 1
#   },
#   ...
# ]
def to_table_from_json(name, json_string)
  begin
    data = JSON.parse(json_string)
  rescue StandardError => e
    return to_table(name, [])
  end
  return to_table(name, []) unless fields.size > 0

  arr_data = []
  arr_data << data[0].keys
  arr_data.push(*data.map(&:values))
  return to_table(name, arr_data)
end


def to_table_from_csv(name, csv_string)
  begin
    data = JSON.parse(json_string)
  rescue StandardError => e
    return to_table(name, [])
  end
  return to_table(name, []) unless fields.size > 0

  arr_data = []
  arr_data << data[0].keys
  arr_data.push(*data.map(&:values))
  return to_table(name, arr_data)
end