.. _tutorial-repo:

The repository
==============

After this introduction, let's start directly with code::

  >>> from dulwich.repo import Repo

The access to a repository is through the Repo object. You can open an
existing repository or you can create a new one. There are two types of Git
repositories:

  Regular Repositories -- They are the ones you create using ``git init`` and
  you daily use. They contain a ``.git`` folder.

  Bare Repositories -- There is no ".git" folder. The top-level folder
  contains itself the "branches", "hooks"... folders. These are used for
  published repositories (mirrors). They do not have a working tree.

Creating a repository
---------------------

Let's create a folder and turn it into a repository, like ``git init`` would::

  >>> from os import mkdir
  >>> import sys
  >>> mkdir("myrepo")
  >>> repo = Repo.init("myrepo")
  >>> repo
  <Repo at 'myrepo'>

You can already look at the structure of the "myrepo/.git" folder, though it
is mostly empty for now.

Opening an existing repository
------------------------------

To reopen an existing repository, simply pass its path to the constructor
of ``Repo``::

    >>> repo = Repo("myrepo")
    >>> repo
    <Repo at 'myrepo'>

Opening the index
-----------------

The index is used as a staging area. Once you do a commit,
the files tracked in the index will be recorded as the contents of the new
commit. As mentioned earlier, only non-bare repositories have a working tree,
so only non-bare repositories will have an index, too. To open the index, simply
call::

    >>> index = repo.open_index()
    >>> print(index.path)
    myrepo/.git/index

Since the repository was just created, the index will be empty::

    >>> list(index)
    []

Staging new files
-----------------

The repository allows "staging" files. Only files can be staged - directories
aren't tracked explicitly by git. Let's create a simple text file and stage it::

    >>> f = open('myrepo/foo', 'wb')
    >>> _ = f.write(b"monty")
    >>> f.close()

    >>> repo.stage([b"foo"])

It will now show up in the index::

    >>> print(",".join([f.decode(sys.getfilesystemencoding()) for f in repo.open_index()]))
    foo


Creating new commits
--------------------

Now that we have staged a change, we can commit it. The easiest way to
do this is by using ``Repo.do_commit``. It is also possible to manipulate
the lower-level objects involved in this, but we'll leave that for a
separate chapter of the tutorial.

To create a simple commit on the current branch, it is only necessary
to specify the message. The committer and author will be retrieved from the
repository configuration or global configuration if they are not specified::

    >>> commit_id = repo.do_commit(
    ...     b"The first commit", committer=b"Jelmer Vernooij <jelmer@samba.org>")

``do_commit`` returns the SHA1 of the commit. Since the commit was to the 
default branch, the repository's head will now be set to that commit::

    >>> repo.head() == commit_id
    True