Working with Git Repositories in Python

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Submitted by nanodano on Tue, 03/17/2020 - 01:22

Introduction

The GitPython project allows you to work in Python with Git repositories. In this guide we'll look at some basic operations like:

  • Initializing a repo
  • Cloning a repo
  • Adding and committing
  • Pushing and pulling with remotes
  • Checking for changes
  • Getting a diff
  • Listing and switching branches

For full documentation, see https://gitpython.readthedocs.io/. The source code is available at https://github.com/gitpython-developers/GitPython.

Installation

You can use pip to install the gitpython package like this:

python -m pip install gitpython

You can also get the source code from https://github.com/gitpython-developers/GitPython and run the setup.py file like this:

git clone https://github.com/gitpython-developers/GitPython
cd GitPython
python setup.py install

Manage repositories

Let's look at some common tasks with Git and how to do them in Python.

Initialize a new repository

To start a new repository, you can use git.Repo.init() which is equivalent to running git init.

import git

# `git init new_repo`
new_repo = git.Repo.init('new_repo')

This will create a new directory named new_repo with the .git directory.

Open an existing local repo

To open an existing repo on disk, pass the repo directory ot the Repo() object initializer:

import git

my_repo = git.Repo('existing_repo')

Clone a remote repository

To clone a remote repository, use git.Repo.clone_from().

import git

# Check out via HTTPS
git.Repo.clone_from('https://github.com/DevDungeon/Cookbook', 'Cookbook-https')
# or clone via ssh (will use default keys)
git.Repo.clone_from('git@github.cim:DevDungeon/Cookbook', 'Cookbook-ssh')

Create a clone of a local repo

You can take an existing repo, load it, and then clone that to another local repo. You might want to do this if you use the primary repository as a template for creating new projects.

import git

# Load existing local repo
my_repo = git.Repo('existing_repo')
# Create a copy of the existing repo
my_repo.clone('/path/to/clone_of_existing_repo')

Work with a repository

Once you have a repository, let's look at some common tasks you will perform when working with a repo like:

  • Checking if there are any changes
  • Get a diff of changes
  • Set git configuration values like user.email and user.name
  • Add and commit files
  • Manage remote repos
  • Push to remote repos
  • Creating branches
  • Listing branches
  • Switching branches

Check if a repo has changes

To check if a repo has any changes, you can use git.Repo.is_dirty().

Here is an example that will also count untracked files as differences:

import git

my_repo = git.Repo('some_repo')
if my_repo.is_dirty(untracked_files=True):
    print('Changes detected.')

Get a diff of file changes

To get the differences on your current repo and see what has changed since the last commit, you can use git.Repo.git.diff() and pass it the tree of your last (HEAD) commit with git.Repo.head.commit.tree.

from git import Repo

repo = Repo('my_repo')

# Check differences between current files and last commit
diff = repo.git.diff(repo.head.commit.tree)
print(diff)

Configure user.name and user.mail

This next example demonstrates how to set the git config values for a repo. Here, we will set the user.name and user.email config values. The end of the example also shows how to use config_reader() to get configuration values.

import git

repo = git.Repo.init('my_new_repo')

with repo.config_writer() as git_config:
    git_config.set_value('user', 'email', 'someone@example.com')
    git_config.set_value('user', 'name', 'John Doe')

# To check configuration values, use `config_reader()`
with repo.config_reader() as git_config:
    print(git_config.get_value('user', 'email'))
    print(git_config.get_value('user', 'name'))

Add and commit files

Once you have determined that a repo has changes and what files have changed, you will want to add and then commit the files to the repository. This example will load a repo and then add two files before committing.

import git

repo = git.Repo('my_repo')

# Provide a list of the files to stage
repo.index.add(['.gitignore', 'README.md'])
# Provide a commit message
repo.index.commit('Initial commit.')

Work with remote repositories

If you want to push or pull from another repository, you will need to have remotes defined. This example will show you how to:

  • List remotes
  • Add remote
  • Remove remote
  • Push
  • Pull
import git

repo = git.Repo('test_repo')

# List remotes
print('Remotes:')
for remote in repo.remotes:
    print(f'- {remote.name} {remote.url}')

# Create a new remote
try:
    remote = repo.create_remote('origin', url='git@github.com:NanoDano/testrepo')
except git.exc.GitCommandError as error:
    print(f'Error creating remote: {error}')

# Reference a remote by its name as part of the object
print(f'Remote name: {repo.remotes.origin.name}')
print(f'Remote URL: {repo.remotes.origin.url}')

# Delete a remote
repo.delete_remote('myremote')

# Pull from remote repo
print(repo.remotes.origin.pull())
# Push changes
print(repo.remotes.origin.push())

Create and switch branches

Branching is a common task to separate development on different tasks. This example shows you how to:

  • List all branches
  • Create a new branch
  • Checkout branches
import git

repo = git.Repo.init('my_new_repo')

# List all branches
for branch in repo.branches:
    print(branch)

# Create a new branch
repo.git.branch('my_new_branch')
# You need to check out the branch after creating it if you want to use it
repo.git.checkout('my_new_branch3')

# To checkout master again:
repo.git.checkout('master')

Conclusion

After reading this guide you should understand how to perform common Git tasks in Python including:

  • Initializing a repo
  • Cloning a repo
  • Adding and committing
  • Pushing and pulling with remotes
  • Checking for changes
  • Listing and switching branches

References

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