Duplicates a database from the master version. Useful for having different databases per branch in a codebase.

database.yml.example

<%
  current_branch_name ||= begin
    `/usr/bin/env git branch` =~ /^\*\s+(.*)$/
    current_branch_name = $1.gsub('-', '_')
  end
%>

development:
  adapter: postgresql
  database: myapp_development_<%= current_branch_name %>
  username: myapp
  host: localhost

test:
  adapter: postgresql
  database: myapp_test_<%= current_branch_name %>
  database: myapp
  host: localhost

duplicate_db.sh

#!/usr/bin/env bash

CURRENT_DB_NAME=`/usr/bin/env ruby <<RUBY
require 'erb'
require 'yaml'

db_config_str = ERB.new(File.read('config/database.yml')).result
db_config = YAML.load(db_config_str)

current_db_name = db_config["development"]["database"]

print current_db_name
RUBY`

if [[ $1 == "" ]]; then
  DB_USERNAME=`/usr/bin/env ruby <<RUBY
  require 'erb'
  require 'yaml'

  db_config_str = ERB.new(File.read('config/database.yml')).result
  db_config = YAML.load(db_config_str)

  user_name = db_config["development"]["username"]

  print user_name
RUBY`

  SOURCE_DB_NAME=`/usr/bin/env ruby <<RUBY
  require 'erb'
  require 'yaml'

  current_branch_name = "master"

  db_config_str = ERB.new(File.read('config/database.yml')).result(binding)
  db_config = YAML.load(db_config_str)

  current_db_name = db_config["development"]["database"]

  print current_db_name
RUBY`
else
  SOURCE_DB_NAME=$1
  DB_USERNAME=$2
fi

if [[ $2 == "" && $DB_USERNAME == "" ]]; then
  echo "Need a source database name and a PG user"
  echo "Usage: duplicate_db <SOURCE_DB_NAME> <DB_USERNAME>"
  exit 1
fi

# echo "Destination database name (default: ${CURRENT_DB_NAME}):"
# read DESTINATION_DB_NAME

# if [[ $DESTINATION_DB_NAME =~ "^ *$" || $DESTINATION_DB_NAME == "" ]]; then
#   DESTINATION_DB_NAME=$CURRENT_DB_NAME
# fi

DESTINATION_DB_NAME=$CURRENT_DB_NAME

echo "Copying the contents of '${SOURCE_DB_NAME}' into '${DESTINATION_DB_NAME}' as user '${DB_USERNAME}'."
echo "Are you sure? [yn]"
read PROCEED

if [[ $PROCEED != "y" ]]; then
  echo "Aborting."
  exit 2
fi

dropdb --if-exists -U $DB_USERNAME $DESTINATION_DB_NAME
createdb -U $DB_USERNAME $DESTINATION_DB_NAME
pg_dump -x --no-owner -U $DB_USERNAME $SOURCE_DB_NAME | psql -U $DB_USERNAME -d $DESTINATION_DB_NAME