Best Practices

The script transfers all SVN revisions of the trunk of a CODESYS SVN project to the "master" branch of a CODESYS Git project.

import os
import shutil
import logging


""" --- inputs ---
"""
# URL of the SVN project you want to migrate
# only migrate a single project at a time if you have multiple in your SVN repo
SVN_REPO_URL = 'svn://your.svnserver.com/trunk/CodesysProjectNr1'
# Starts migration at this svn revision
STARTING_REVISION = 0
# Directory of the new project with the git repository
NEW_PROJECT_DIR = 'C:/CodesysProjects/CodesysProjectNr1'
# Name of the new project
NEW_PROJECT_NAME = 'CodesysProjectNr1'
# Is the project a library (otherwise will be checked out as a project)
IS_LIBRARY = False
# Path to the local git repository of the new project
NEW_PROJECT_REPO_DIR = 'C:/CodesysProjects/CodesysProjectNr1/repo'

# Path to an EMPTY temporary folder (doesn't have to exist) that can be deleted
TEMP_PATH = 'C:/CodesysProjects/CodesysProjectNr1/temp'

# Author of the git commits
AUTHOR_NAME = 'Author Name'
# E-mail address of the git commits
AUTHOR_EMAIL = 'Author.Name@e-mail.com'

# Name of the branch that should contain the history
# Can't be named 'master'
TARGET_BRANCH_NAME = 'develop'
# Initial commit messages on the master branch and the target branch
IC_MSG_MASTER = 'master: Initial commit.'
IC_MSG_TARGET_BRANCH = 'develop: Initial commit.'

# Removes the newly created project and its repository if the migration fails
REMOVE_MAIN_PROJECT_ON_FAILURE = True


def get_git_commit_msg(svn_log):
    """ Returns the commit messages that will be seen in the resulting git history
        Can be customized to ones demands.
        *svn_log* see: https://content.helpme-codesys.com/en/ScriptingEngine/ScriptSubversion.html#ScriptSubversion.LogInfo
    """
    return 'SVN revision %d: %s' % (svn_log.revision, svn_log.message)


""" --- migration script ---
"""
# Type extension of the project (.project / .library)
PROJECT_FILE_TYPE_EXTENSION = '.library' if IS_LIBRARY else '.project'
# Path to your new Git project
NEW_MAIN_PROJECT_PATH = os.path.join(NEW_PROJECT_DIR, NEW_PROJECT_NAME + PROJECT_FILE_TYPE_EXTENSION)
# Name of the temporarily added remote
TEMP_REMOTE_NAME = 'remote1'
# Temporary commit message will be overwritten/amended (put what u like)
TEMP_COMMIT_MSG = 'TEMP COMMIT: This will be overwritten'


def create_git_project():
    """ 1. Creates a new project at *NEW_MAIN_PROJECT_PATH*
        2. Initializes it in git with the repository at *NEW_PROJECT_REPO_DIR*
        3. Makes an initial commit with the message *IC_MSG_MASTER*
        4. Creates and switches to the target branch *TARGET_BRANCH_NAME*
        5. Makes an initial commit on the target branch with the message *IC_MSG_TARGET_BRANCH*
        6. Saves and closes the project
    """
    git_project = projects.create(NEW_MAIN_PROJECT_PATH)
    git_project.git.init(NEW_PROJECT_REPO_DIR)
    git_project.git.commit_complete(IC_MSG_MASTER, AUTHOR_NAME, AUTHOR_EMAIL)

    git_project, git_branch = git_project.git.branch_copy(TARGET_BRANCH_NAME, checkout=True)
    git_project.git.commit_complete(IC_MSG_TARGET_BRANCH, AUTHOR_NAME, AUTHOR_EMAIL, bAllowEmptyCommits=True)

    git_project.save()
    git_project.close()


def remove_all_children(project):
    """ Removes all objects that can be removed from the project *project*
    """
    children = project.get_children(recursive=True)
    for child in children:
        try:
            child.remove()
        except Exception as ex:
            if not 'Object reference not set to an instance of an object.' == str(ex):
                logging.error(ex)


def create_git_repo_from_svn_revision(svn_log):
    """ 1. Checks out a project from the SVN server *SVN_REPO_URL*
        2. Disconnects it from SVN
        3. Initiates it in git with the repository at *repo_dir*
        4. Makes a commit with the message *commit_message*
            4.1 See "get_git_commit_msg" to customize the commit message
        5. Saves and closes the project
        6. Returns the path of the project and path of the repository
    """
    project_path = os.path.join(TEMP_PATH, 'revision_' + str(svn_log.revision) + PROJECT_FILE_TYPE_EXTENSION)
    repo_dir = os.path.join(TEMP_PATH, 'repo_' + str(svn_log.revision))
    commit_message = get_git_commit_msg(svn_log)

    temp_project_name = 'revision_%d' % svn_log.revision
    svn_project = svn.checkout(SVN_REPO_URL, TEMP_PATH, temp_project_name, svn_log.revision, as_library=IS_LIBRARY)

    svn_project.svn.disconnect()
    svn_project.git.init(repo_dir)
    svn_project.git.commit_complete(commit_message, AUTHOR_NAME, AUTHOR_EMAIL)
    svn_project.save()
    svn_project.close()

    return project_path, repo_dir


def magic_git_pull(project, temp_repo_path, svn_log):
    """ 1. Removes everything from the *project* (to insure svn revision and git commit match exactly)
        2. Pulls from the repo at *repo_path*
        4. Commits the changes with the commit message *commit_message*
        5. Saves and closes the project
    """
    remove_all_children(project)

    # Temp commit for fake git merge --squash
    project.git.commit_complete(TEMP_COMMIT_MSG, AUTHOR_NAME, AUTHOR_EMAIL, bAllowEmptyCommits=True)

    project.git.remote_add(TEMP_REMOTE_NAME, temp_repo_path)
    project.git.fetch(TEMP_REMOTE_NAME)
    project.git.branch_track('refs/remotes/%s/master' % TEMP_REMOTE_NAME, TARGET_BRANCH_NAME)

    pull_options = git.get_pull_options()
    pull_options.fast_forward_strategy = GitFastForwardStrategy.NoFastForward
    pull_options.resolve_file_conflict_strategy = GitResolveFileConflictStrategy.Theirs
    project, merge_result = project.git.pull(AUTHOR_NAME, AUTHOR_EMAIL, pull_options)

    commit_message = get_git_commit_msg(svn_log)
    project.git.commit_complete(commit_message, AUTHOR_NAME, AUTHOR_EMAIL, bAllowEmptyCommits=True, bAmendCommit=True)

    project.git.branch_unset_upstream()
    project.git.remote_remove(TEMP_REMOTE_NAME)

    project.save()
    project.close()


def remove_repo(project_path):
    try:
        project = projects.open(project_path)
        project.git.de_init(True)
        project.close()
    except:
        pass


def remove_temp_project(project_path):
    """ Opens the project at *project_path* and deinitializes its git repository
        This needs to be done because the script can't delete the repository with "shutil.rmtree"
        Removes the rest of the contents int the folder at *TEMP_PATH*
        Removes the temporary .project/.library files and their associated files
    """
    remove_repo(project_path)
    try:
        shutil.rmtree(TEMP_PATH)
        os.makedirs(TEMP_PATH)
    except Exception as e:
        logging.error('Failed to delete %s. Reason: %s' % (TEMP_PATH, e))


def main():
    if projects.primary is not None:
        projects.primary.close()

    create_git_project()

    # get the list of all revision of SVN_REPO_URL
    # oldest to newest
    # starting at revision STARTING_REVISION + 1
    svn_logs = list(reversed(svn.get_log(SVN_REPO_URL)))
    svn_logs_to_migrate = [log for log in svn_logs if STARTING_REVISION <= log.revision]
    assert svn_logs_to_migrate, ('Nothing to migrate. STARTING_REVISION is greater than the newest '
                                 'revision in %s') % SVN_REPO_URL

    system.prompt_answers['LossOfDataWarning2'] = PromptResult.Yes
    no_project_root_dir_amount = 0
    try:
        for svn_log in svn_logs_to_migrate:
            try:
                temp_project_path, temp_git_repo_path = create_git_repo_from_svn_revision(svn_log)

                # pull to your main Git project
                git_project = projects.open(NEW_MAIN_PROJECT_PATH)

                magic_git_pull(git_project, temp_git_repo_path, svn_log)

                # can be omitted if enough storage space is available (big performance increase)
                # if omitted the folder at "TEMP_PATH" needs to be deleted manually
                # needed storage space = (project file size + project git repository size) * revisions
                # example:   255.16 MB = (1.6 KB + 2.55 MB) * 100
                remove_temp_project(temp_project_path)
            except ValueError as ve:
                # Early svn revisions often do not contain a codesys project
                if ('The URL %s is not a project root directory.' % SVN_REPO_URL) == str(ve):
                    no_project_root_dir_amount += 1
                    if no_project_root_dir_amount < len(svn_logs_to_migrate):
                        logging.info(ve)
                        continue
                logging.critical(ve)
                raise
    except:
        if REMOVE_MAIN_PROJECT_ON_FAILURE:
            remove_repo(NEW_MAIN_PROJECT_PATH)
            for file in os.listdir(NEW_PROJECT_DIR):
                if file.startswith(NEW_PROJECT_NAME):
                    os.remove(os.path.join(NEW_PROJECT_DIR, file))
        raise
    finally:
        system.prompt_answers.clear()


if __name__ == '__main__':
    main()