This is a nasty and naughty hack, and one I’m abashedly apologetic for.

I was doing some work on a personal project recently, and wanted to pull some data out of the live database. I only needed a few columns from a couple of tables, so it didn’t seem to warrant a SQL dump.

I decided to format the records as JSON data, and copy/paste them from the console directly. But it turned out the length of the JSON data was longer than the backtrace in my terminal window, so I wasn’t able to see it all at once to select, copy, and paste.

Instead, I decided to save the data in a temporary file, and then email it to myself—using a temporary, memory-only mailer object.

Since this code was only held in memory during my rails console session, it disappeared as soon as I exited the session.

Here’s the code I used to do that:

array = # ... get all of the data that I need from the DB

# Create the Tempfile object
tempfile ="my-data")
# Write the data to the tempfile as JSON

# Subclass ApplicationMailer in memory
class DynamicMailer < ApplicationMailer

  # Define a mailer method to send myself the file we just created
  def send_attachment(tempfile)
    attachments['attached.json'] =
    mail(to: '[email protected]',
         body: "",
         subject: "Incoming...")

# Send the email

# Clean up the Tempfile afterwards

Hopefully the annotations in the code example make sense.

  1. I pulled the data that I wanted from the database in an Array of Hashes
  2. I created a Tempfile to store the data in
  3. I wrote the data to the Tempfile in the JSON format
  4. I created a new Mailer class in memory with one method for sending attached files
  5. I sent myself the Tempfile full of JSON
  6. I cleaned up the Tempfile afterwards.

I don’t advise that you ever use this horrible little hack for anything, on any project, ever.

Written by

Photo of Gavin Morrice
Gavin Morrice

Software engineer based in Scotland

Work with me

Need help with some code?

In my free time, I like to help people improve their code and skills on Codementor.
Contact me on Codementor


Handy Rails Tips

Ruby on Rails tips and tutorials

Back to home