Automatic django migration handling for git workflow

django-git-switch-migrate.sh

#!/bin/bash
# ==============================================================================
#  Git Branch Switch with Safe Django Migrations
# ==============================================================================
#  This script automates switching between Git branches in a Django project
#  while handling database migrations safely.
#
#  It:
#    - Compares Django migrations between the current and target branches.
#    - Reverts apps to the last common migration if migrations diverged.
#    - Switches branches.
#    - Applies the latest migrations for the new branch.
#
#  USAGE:
#    git pswitch <branch-name>
#
#  EXAMPLE:
#    git pswitch feature/new-ui
#
#  SETUP AS A GIT ALIAS:
#    1. Save this script as `.git-pswitch` in your project root or somewhere in your PATH.
#    2. Make it executable:
#         chmod +x .git-pswitch
#    3. Add the alias to your Git configuration:
#         git config --global alias.pswitch '!bash .git-pswitch'
#
#  After setup, you can simply run:
#         git pswitch main
#
# ==============================================================================

set -e

MIGRATE_COMMAND="python manage.py migrate"

current_branch=$(git rev-parse --abbrev-ref HEAD);
target_branch=$1

if [ -z \"$target_branch\" ]; then \
  echo 'Usage: git pswitch <branch>'; \
  return 1; \
fi;

if [ "$current_branch" == "$target_branch" ]; then
  echo "Already on branch '$target_branch'. No switch needed."
  exit 0
fi

if ! git show-ref --verify --quiet "refs/heads/$target_branch"; then
  echo "Branch '$target_branch' does not exist."
  exit 1
fi

# The root directory where Django apps are located
APPS_ROOT="apps"
apps_to_revert=()

# Loop over all apps
while read -r migrations_dir; do
  app=$(basename "$(dirname "$migrations_dir")")

  # --- Migrations from old branch ---
  mapfile -t old_migrations < <(
    git ls-tree -r --name-only "$current_branch" -- "$migrations_dir" 2>/dev/null |
      grep '/[0-9]\+_.*\.py$' |
      xargs -n1 basename |
      sed 's/\.py$//' |
      sort
  )

  # --- Migrations from new branch ---
  mapfile -t new_migrations < <(
    git ls-tree -r --name-only "$target_branch" -- "$migrations_dir" 2>/dev/null |
      grep '/[0-9]\+_.*\.py$' |
      xargs -n1 basename |
      sed 's/\.py$//' |
      sort
  )

  # If the migrations are identical, skip
  diff_output=$(diff <(printf '%s\n' "${old_migrations[@]}") <(printf '%s\n' "${new_migrations[@]}") || true)
  if [ -z "$diff_output" ]; then
    continue
  fi

  # --- Find last common migration ---
  last_common=""
  for mig in "${old_migrations[@]}"; do
    if printf '%s\n' "${new_migrations[@]}" | grep -qx "$mig"; then
      last_common="$mig"
    else
      break
    fi
  done

  # If migrations are missing or diverged, record the app
  if [ -n "$last_common" ]; then
    apps_to_revert+=("$app $last_common")
  fi
done < <(find "$APPS_ROOT" -type d -name "migrations")

if [ ${#apps_to_revert[@]} -eq 0 ]; then exit 0; fi

echo "The following apps will be reverted to previous migrations:"
for entry in "${apps_to_revert[@]}"; do
  read -r app migration <<< "$entry"
  echo " - $app $migration"
done

for entry in "${apps_to_revert[@]}"; do
  read -r app migration <<< "$entry"
  $MIGRATE_COMMAND "$app" "$migration"
done

git switch "$target_branch" 

$MIGRATE_COMMAND

echo "Switched to branch '$target_branch' and applied necessary migrations."