Ruby+MySQL on Ubuntu
This post goes through installing and configuring Ruby and Ruby on Rails for MySQL. The first step requires updating the Ubuntu OS:
sudo apt-get update |
Interestingly, I found that the man-db service had inadvertently stopped. It raised the following error:
E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem. |
You run this command to find the problem with the dpkg utility:
sudo dpkg --configure -a |
It returned:
Setting up man-db (2.10.2-1) ... Updating database of manual pages ... man-db.service is a disabled or a static unit not running, not starting it. |
The following command started the man-db service:
sudo systemctl start man-db.service |
Next, you install the prerequisite packages with this command:
sudo apt-get install -y git-core zlib1g-dev build-essential libssl-dev libreadline-dev libyaml-dev libsqlite3-dev sqlite3 libxml2-dev libxslt1-dev libcurl4-openssl-dev software-properties-common libffi-dev |
Display detailed console log →
Reading package lists... Done Building dependency tree... Done Reading state information... Done Note, selecting 'git' instead of 'git-core' build-essential is already the newest version (12.9ubuntu3). build-essential set to manually installed. libreadline-dev is already the newest version (8.1.2-1). libreadline-dev set to manually installed. git is already the newest version (1:2.34.1-1ubuntu1.10). git set to manually installed. software-properties-common is already the newest version (0.99.22.9). zlib1g-dev is already the newest version (1:1.2.11.dfsg-2ubuntu9.2). zlib1g-dev set to manually installed. The following additional packages will be installed: libssl3 Suggested packages: libcurl4-doc libidn11-dev libkrb5-dev libldap2-dev librtmp-dev libssh2-1-dev sqlite3-doc libssl-doc libyaml-doc The following NEW packages will be installed: libcurl4-openssl-dev libffi-dev libsqlite3-dev libxml2-dev libxslt1-dev libyaml-dev sqlite3 The following packages will be upgraded: libssl-dev libssl3 2 upgraded, 7 newly installed, 0 to remove and 18 not upgraded. Need to get 7,426 kB of archives. After this operation, 12.8 MB of additional disk space will be used. Get:1 http://us.archive.ubuntu.com/ubuntu jammy-updates/main amd64 libssl-dev amd64 3.0.2-0ubuntu1.13 [2,374 kB] Get:2 http://us.archive.ubuntu.com/ubuntu jammy-updates/main amd64 libssl3 amd64 3.0.2-0ubuntu1.13 [1,902 kB] Get:3 http://us.archive.ubuntu.com/ubuntu jammy-updates/main amd64 libcurl4-openssl-dev amd64 7.81.0-1ubuntu1.15 [386 kB] Get:4 http://us.archive.ubuntu.com/ubuntu jammy-updates/main amd64 libsqlite3-dev amd64 3.37.2-2ubuntu0.3 [846 kB] Get:5 http://us.archive.ubuntu.com/ubuntu jammy-updates/main amd64 libxml2-dev amd64 2.9.13+dfsg-1ubuntu0.3 [804 kB] Get:6 http://us.archive.ubuntu.com/ubuntu jammy-updates/main amd64 libxslt1-dev amd64 1.1.34-4ubuntu0.22.04.1 [219 kB] Get:7 http://us.archive.ubuntu.com/ubuntu jammy-updates/main amd64 sqlite3 amd64 3.37.2-2ubuntu0.3 [768 kB] Get:8 http://us.archive.ubuntu.com/ubuntu jammy/main amd64 libffi-dev amd64 3.4.2-4 [63.7 kB] Get:9 http://us.archive.ubuntu.com/ubuntu jammy/main amd64 libyaml-dev amd64 0.2.2-1build2 [62.8 kB] Fetched 7,426 kB in 1s (5,467 kB/s) Preconfiguring packages ... (Reading database ... 246735 files and directories currently installed.) Preparing to unpack .../libssl-dev_3.0.2-0ubuntu1.13_amd64.deb ... Unpacking libssl-dev:amd64 (3.0.2-0ubuntu1.13) over (3.0.2-0ubuntu1.12) ... Preparing to unpack .../libssl3_3.0.2-0ubuntu1.13_amd64.deb ... Unpacking libssl3:amd64 (3.0.2-0ubuntu1.13) over (3.0.2-0ubuntu1.12) ... Setting up libssl3:amd64 (3.0.2-0ubuntu1.13) ... Selecting previously unselected package libcurl4-openssl-dev:amd64. (Reading database ... 246735 files and directories currently installed.) Preparing to unpack .../0-libcurl4-openssl-dev_7.81.0-1ubuntu1.15_amd64.deb ... Unpacking libcurl4-openssl-dev:amd64 (7.81.0-1ubuntu1.15) ... Selecting previously unselected package libsqlite3-dev:amd64. Preparing to unpack .../1-libsqlite3-dev_3.37.2-2ubuntu0.3_amd64.deb ... Unpacking libsqlite3-dev:amd64 (3.37.2-2ubuntu0.3) ... Selecting previously unselected package libxml2-dev:amd64. Preparing to unpack .../2-libxml2-dev_2.9.13+dfsg-1ubuntu0.3_amd64.deb ... Unpacking libxml2-dev:amd64 (2.9.13+dfsg-1ubuntu0.3) ... Selecting previously unselected package libxslt1-dev:amd64. Preparing to unpack .../3-libxslt1-dev_1.1.34-4ubuntu0.22.04.1_amd64.deb ... Unpacking libxslt1-dev:amd64 (1.1.34-4ubuntu0.22.04.1) ... Selecting previously unselected package sqlite3. Preparing to unpack .../4-sqlite3_3.37.2-2ubuntu0.3_amd64.deb ... Unpacking sqlite3 (3.37.2-2ubuntu0.3) ... Selecting previously unselected package libffi-dev:amd64. Preparing to unpack .../5-libffi-dev_3.4.2-4_amd64.deb ... Unpacking libffi-dev:amd64 (3.4.2-4) ... Selecting previously unselected package libyaml-dev:amd64. Preparing to unpack .../6-libyaml-dev_0.2.2-1build2_amd64.deb ... Unpacking libyaml-dev:amd64 (0.2.2-1build2) ... Setting up libyaml-dev:amd64 (0.2.2-1build2) ... Setting up libffi-dev:amd64 (3.4.2-4) ... Setting up libxml2-dev:amd64 (2.9.13+dfsg-1ubuntu0.3) ... Setting up libsqlite3-dev:amd64 (3.37.2-2ubuntu0.3) ... Setting up libcurl4-openssl-dev:amd64 (7.81.0-1ubuntu1.15) ... Setting up libssl-dev:amd64 (3.0.2-0ubuntu1.13) ... Setting up sqlite3 (3.37.2-2ubuntu0.3) ... Setting up libxslt1-dev:amd64 (1.1.34-4ubuntu0.22.04.1) ... Processing triggers for man-db (2.10.2-1) ... Processing triggers for install-info (6.8-4build1) ... Processing triggers for libc-bin (2.35-0ubuntu3.6) ... |
Use the cd command to change to the student home directory. Clone the asdf as the multiple runtime version manager with this command:
git clone https://github.com/excid3/asdf.git ~/.asdf |
The following is the output of the git clone command:
Cloning into '/home/student/.asdf'... remote: Enumerating objects: 8756, done. remote: Counting objects: 100% (829/829), done. remote: Compressing objects: 100% (476/476), done. remote: Total 8756 (delta 428), reused 657 (delta 334), pack-reused 7927 Receiving objects: 100% (8756/8756), 3.10 MiB | 4.29 MiB/s, done. Resolving deltas: 100% (5148/5148), done. |
Next, you fix your .bashrc file by adding the following components:
echo '. "$HOME/.asdf/asdf.sh"' >> ~/.bashrc echo '. "$HOME/.asdf/completions/asdf.bash"' >> ~/.bashrc echo 'legacy_version_file = yes' >> ~/.asdfrc echo 'export EDITOR="code --wait"' >> ~/.bashrc |
Source the modifies shell, which you can do like this:
exec $SHELL |
or, like:
. ${HOME}/.bashrc |
Add the following asdf plug-ins:
asdf plugin add ruby asdf plugin add nodejs |
Install Ruby with the following command:
asdf install ruby 3.3.0 |
Display detailed console log →
Downloading ruby-build...
==> Downloading ruby-3.3.0.tar.gz...
-> curl -q -fL -o ruby-3.3.0.tar.gz https://cache.ruby-lang.org/pub/ruby/3.3/ruby-3.3.0.tar.gz
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 21.0M 100 21.0M 0 0 10.1M 0 0:00:02 0:00:02 --:--:-- 10.1M
==> Installing ruby-3.3.0...
-> ./configure "--prefix=$HOME/.asdf/installs/ruby/3.3.0" --enable-shared --with-ext=openssl,psych,+
-> make -j 2
-> make install
==> Installed ruby-3.3.0 to /home/student/.asdf/installs/ruby/3.3.0
asdf: Warn: You have configured asdf to preserve downloaded files (with always_keep_download=yes or --keep-download). But
asdf: Warn: the current plugin (ruby) does not support that. Downloaded files will not be preserved. |
Install Ruby Global with this syntax:
asdf global ruby 3.3.0 |
Update the Ruby Gems with this command:
gem update --system |
Display detailed console log →
Updating rubygems-update Fetching rubygems-update-3.5.5.gem Successfully installed rubygems-update-3.5.5 Parsing documentation for rubygems-update-3.5.5 Installing ri documentation for rubygems-update-3.5.5 Done installing documentation for rubygems-update after 1 seconds Parsing documentation for rubygems-update-3.5.5 Done installing documentation for rubygems-update after 0 seconds Installing RubyGems 3.5.5 Successfully built RubyGem Name: bundler Version: 2.5.5 File: bundler-2.5.5.gem Bundler 2.5.5 installed RubyGems 3.5.5 installed Regenerating binstubs Regenerating plugins Parsing documentation for rubygems-3.5.5 Installing ri documentation for rubygems-3.5.5 # 3.5.5 / 2024-01-18 ## Enhancements: * Installs bundler 2.5.5 as a default gem. ## Bug fixes: * Fix `require` activation conflicts when requiring default gems under some situations. Pull request [#7379](https://github.com/rubygems/rubygems/pull/7379) by deivid-rodriguez * Use cache_home instead of data_home in default_spec_cache_dir. Pull request [#7331](https://github.com/rubygems/rubygems/pull/7331) by mrkn ## Documentation: * Use squiggly heredocs in `Gem::Specification#description` documentation, so it doesn't add leading whitespace. Pull request [#7373](https://github.com/rubygems/rubygems/pull/7373) by bravehager # 3.5.4 / 2024-01-04 ## Enhancements: * Always avoid "Updating rubygems-update" message. Pull request [#7335](https://github.com/rubygems/rubygems/pull/7335) by deivid-rodriguez * Installs bundler 2.5.4 as a default gem. ## Bug fixes: * Make `gem update --system` respect ruby version constraints. Pull request [#7334](https://github.com/rubygems/rubygems/pull/7334) by deivid-rodriguez ------------------------------------------------------------------------------ RubyGems installed the following executables: /home/student/.asdf/installs/ruby/3.3.0/bin/gem /home/student/.asdf/installs/ruby/3.3.0/bin/bundle /home/student/.asdf/installs/ruby/3.3.0/bin/bundler Ruby Interactive (ri) documentation was installed. ri is kind of like man pages for Ruby libraries. You may access it like this: ri Classname ri Classname.class_method ri Classname#instance_method If you do not wish to install this documentation in the future, use the --no-document flag, or set it as the default in your ~/.gemrc file. See 'gem help env' for details. RubyGems system software updated |
You can confirm your Ruby install with two commands. First, use the which utility to check the Ruby install:
which -a ruby |
It should return:
/home/student/.asdf/shims/ruby |
Then, check the Ruby version:
ruby -v |
It should return:
ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-linux] |
Assuming you’ve installed and configured MySQL 8 on Ubuntu, you need this additional library to support the necessary Ruby Gem:
sudo apt-get install -y libmysqlclient-dev |
Now, you can install the current MySQL Ruby Gem:
gem install mysql2 |
You can now write a mysql_connection.rb program to verify a connection to the MySQL 8 database, like:
# Include Ruby Gem libraries. require 'rubygems' require 'mysql2' begin # Create new database connection. db = Mysql2::Client.new( :host => 'localhost' \ , :username => 'student' \ , :password => 'student' \ , :database => 'studentdb') # Create a result set. stmt = db.query('SELECT version() AS version') # Read through the result set hash. stmt.each do | row | puts "#{row['version']}" end # Release the result set resources. stmt.free rescue Mysql2::Error => e # Print the error. puts "ERROR #{e.errno} (#{e.sqlstate}): #{e.error}" puts "Can't connect to the MySQL database specified." # Signal an error. exit 1 ensure # Close the connection when it is open. db.close if db end |
Call the program with this syntax:
ruby mysql_connection.rb |
It should return:
Connected to the MySQL database server. |
You can verify the version with this mysql_version.rb program:
# Include Ruby Gem libraries. require 'rubygems' require 'mysql2' begin # Create new database connection. db = Mysql2::Client.new( :host => 'localhost' \ , :username => 'student' \ , :password => 'student' \ , :database => 'studentdb') # Create a result set. rs = db.query('SELECT version() AS version') # Read through the result set hash. rs.each do | row | puts "#{row['version']}" end # Release the result set resources. rs.free rescue Mysql2::Error => e # Print the error. puts "ERROR #{e.errno} (#{e.sqlstate}): #{e.error}" puts "Can't connect to the MySQL database specified." # Signal an error. exit 1 ensure # Close the connection when it is open. db.close if db end |
On Ubuntu, it should return:
8.0.35-0ubuntu0.22.04.1 |
If you don’t know anything about the mysql2 Ruby Gem, you should read the documentation. It’s very concise and requires a basic understanding of Ruby programming. The two specific pages who may want to check for the next examples are:
- The Mysql2 Statement Class list.
- The Mysql2 Result Class List
The mysql_version.rb version uses the known string literal for columns or column aliases returned by the SQL statement, which becomes the stmt (or statement) in the program. The next program eliminates the need to enumerate with the text-based columns from the query by using the Statement#fields array values by use of a numeric index. The numeric index returns the field names from the Statement#fields class to use in as the name for values in the Result#fields value found in the row variable of the for loop.
# Include Ruby Gem libraries. require 'rubygems' require 'mysql2' # Begin block. begin # Create a new connection resource. db = Mysql2::Client.new( :host => 'localhost' \ , :username => 'student' \ , :password => 'student' \ , :database => 'studentdb') # Create a result set. stmt = db.query("SELECT DISTINCT i.item_title, ra.rating " + \ "FROM item i INNER JOIN rating_agency ra " + \ "ON i.item_rating_id = ra.rating_agency_id " + \ "WHERE ra.rating_agency = 'MPAA'" + \ "ORDER BY 1") # Read through the result set hash. stmt.each do | row | out = "" i = 0 while i < stmt.fields.count() # Check when not last column and use the: # - Hash returned by the result set for the value, and # - String array value returned by the statement object # as the name value of the hash by leveraging its # numeric index. if i < stmt.fields.count() - 1 out += "#{row[stmt.fields[i]]}" out += ", " else out += "#{row[stmt.fields[i]]}" end i += 1 end puts "#{out}" end # Release the result set resources. stmt.free rescue Mysql2::Error => e # Print the error. puts "ERROR #{e.errno} (#{e.sqlstate}): #{e.error}" puts "Can't connect to MySQL database specified." # Signal an error. exit 1 ensure # Close the connection when it is open. db.close if db end |
It returns the select two columns from the query:
A Man for All Seasons, G Around the World in 80 Days, G Beau Geste, PG Brave Heart, R Camelot, G Casino Royale, PG-13 ... Tomorrow Never Dies, PG-13 Tora! Tora! Tora!, G Tron, PG |
The following mysql_query_params.rb Ruby example accepts a single argument to leverage a wild card query in MySQL:
require 'rubygems' require 'mysql2' # Input external arguments. arguments = ARGV # Check for one input parameter and substitute an empty string # when one isn't found. if arguments.length == 1 argument = arguments[0] else argument = "" end # Begin block. begin # Create a new connection resource. db = Mysql2::Client.new( :host => 'localhost' \ , :username => 'student' \ , :password => 'student' \ , :database => 'studentdb') # Create a result set. stmt = db.prepare("SELECT DISTINCT i.item_title, ra.rating " + \ "FROM item i INNER JOIN rating_agency ra " + \ "ON i.item_rating_id = ra.rating_agency_id " + \ "WHERE ra.rating_agency = 'MPAA'" + \ "AND i.item_title LIKE CONCAT(?,'%')" + \ "ORDER BY 1") # Bind the variable into the query. rs = stmt.execute(argument) # Read through the result set hash. rs.each do | row | out = "" i = 0 while i < rs.fields.count() # Check when not last column and use the: # - Hash returned by the result set for the value, and # - String array value returned by the statement object # as the name value of the hash by leveraging its # numeric index. if i < rs.fields.count() - 1 out += "#{row[rs.fields[i]]}" out += ", " else out += "#{row[rs.fields[i]]}" end i += 1 end puts "#{out}" end # Release the result set resources. rs.free rescue Mysql2::Error => e # Print the error. puts "ERROR #{e.errno} (#{e.sqlstate}): #{e.error}" puts "Can't connect to MySQL database specified." # Signal an error. exit 1 ensure # Close the connection when it is open. db.close if db end |
If you call the mysql_query_params.rb program with this syntax:
ruby mysql_aquery_params.rb Harry |
It’ll return the following from the studentdb database:
Harry Potter and the Chamber of Secrets, PG Harry Potter and the Deathly Hallows, Part 1, PG-13 Harry Potter and the Deathly Hallows, Part 2, PG-13 Harry Potter and the Goblet of Fire, PG-13 Harry Potter and the Half Blood Prince, PG Harry Potter and the Order of the Phoenix, PG-13 Harry Potter and the Prisoner of Azkaban, PG Harry Potter and the Sorcerer's Stone, PG |
After that, you should install Rails (check for current version beyond 1/2024). Install Ruby Global with this syntax:
gem install rails -v 7.1.3 |
Check the version installed:
rails -v |
It should return:
Rails 7.1.3 |
Run this command to enable Rails for MySQL 8:
rails new myapp -d mysql |
If you want to configure a username and password for MySQL, edit the config/database.yml file.
As always, I hope this helps somebody looking for step-by-step guide.
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