How can I write table_print output within my Ruby script?

Question

So, I've got a script, say, program.rb, and in it I want to output the table_print version of an array of lists

['value1','value2','value3']
['value4','value4','value6']

so that it looks like this in the .txt file I output

  col1              | col2              | col3
  -------------------------------------------------------------------------
  value1            | value2            | value3
  .
  .
  .

I already have table_print installed, but this is all I have so far as a working model:

require 'table_print'

TABLEPRINT STUFF?

open('table_print_output.txt','a'){|g|
    g.puts TABLEPRINT?
}

I guess I'm just not getting how to do the Ruby equivalent of MySQL's create table

CREATE TABLE MyGuests (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
firstname VARCHAR(30) NOT NULL,
lastname VARCHAR(30) NOT NULL,
email VARCHAR(50),
reg_date TIMESTAMP
)

and insert into

INSERT INTO table_name (column1, column2, column3,...)
VALUES (value1, value2, value3,...)

And I don't want a temporary/latent database just sitting around for no reason. It's like I need a database as a variable or something; that is, I create it, I populate it, I print it, I destroy it.

Do try and allow a little more room for names and email addresses. Unless you have a very compelling reason to restrict something, use VARCHAR(255) as a default. — tadman
– tadman, Commented Sep 9, 2016 at 1:47
Yes, I know, I use VARCHAR(255), I just copied that as an example. — Forwarding
– Forwarding, Commented Sep 9, 2016 at 5:05

Stefan · Accepted Answer · 2016-09-09 09:58:11Z

table_print can't print nested arrays like this:

arrays = [
  ['value1', 'value2', 'value3'],
  ['value4', 'value5', 'value6']
]

because it flattens the input. You have to convert the inner arrays to another object.

Hash would work:

hashes = array.map { |values| %w(col1 col2 col3).zip(values).to_h }
#=> [
#     {"col1"=>"value1", "col2"=>"value2", "col3"=>"value3"},
#     {"col1"=>"value4", "col2"=>"value5", "col3"=>"value6"}
#   ]

tp hashes
# COL1   | COL2   | COL3
# -------|--------|-------
# value1 | value2 | value3
# value4 | value5 | value6

Struct would work as well:

Row = Struct.new(:col1, :col2, :col3)
rows = arrays.map { |values| Row.new(*values) }
#=> [
#     #<struct Row col1="value1", col2="value2", col3="value3">,
#     #<struct Row col1="value4", col2="value5", col3="value6">
#   ]

tp rows
# COL1   | COL2   | COL3
# -------|--------|-------
# value1 | value2 | value3
# value4 | value5 | value6

seph · Accepted Answer · 2016-09-09 03:12:04Z

1

Looks like you need String#ljust:

rows = [
  ['value1','value2','value3'],
  ['value4','value4','value6']
]

rows.each do |row|
  puts "#{row[0].ljust(30)}|#{row[1].ljust(30)}|#{row[2].ljust(30)}"
end

answered Sep 9, 2016 at 3:12

seph

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