Simple script to create and apply a patch file to deal with misaligned migrations / databases

migration-patch

#!/bin/bash

scriptname="$(basename "$(test -L "$0" && readlink "$0" || echo "$0")")"
dir="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
patch="$dir/migration.patch"

read -r -d '' help << EOM
Usage:
  $scriptname command [file]

Create / apply patch file to better manage changes, annotations and specs
caused by db migrations and misaligned databases

Commands:
  create      Create the patch file
  apply       Apply the patch file
  help        Display this text

Options
  file        File to save the patch file in
              (current: $patch)
EOM

display-help () 
{
  echo "$help"
}

exit-if-dirty ()
{
 if [[ `git status --porcelain` ]]; then
  echo "Changes must be committed or stashed before creating patch!"
  exit 1
 fi
}

do-migrate ()
{
  spring rake db:migrate > /dev/null
}

create-patch ()
{
  temp="$patch.temp"
  git diff -u > $temp --color=never
  interdiff $temp /dev/null > $patch
  rm $temp
}

apply-patch ()
{
  git apply $patch
}

if [ $# -eq 0 ] ; then
  display-help
  exit 1
fi

if [ $# -gt 1 ] ; then
  patch="$2"
fi

case "$1" in
  help)
    display-help
    exit 0
    ;;
  apply)
    apply-patch
    exit 0
    ;;
  create)
    exit-if-dirty
    do-migrate
    create-patch
    apply-patch
    exit 0
    ;;
  *)
    display-help
    exit 1
    ;;
esac