deb-python-pygit2/docs/objects.rst

Git Objects

There are four types of Git objects: blobs, trees, commits and tags. For each one pygit2 has a type, and all four types inherit from the base Object type.

Contents

Object lookup

In the previous chapter we learnt about Object IDs. With an oid we can ask the repository to get the associated object. To do that the Repository class implementes a subset of the mapping interface.

Repository.get(oid, default=None)

Return the Git object for the given oid, returns the default value if there's no object in the repository with that oid. The oid can be an Oid object, or an hexadecimal string.

Example:

>>> from pygit2 import Repository
>>> repo = Repository('path/to/pygit2')
>>> obj = repo.get("101715bf37440d32291bde4f58c3142bcf7d8adb")
>>> obj
<_pygit2.Commit object at 0x7ff27a6b60f0>

Repository[oid]

Return the Git object for the given oid, raise KeyError if there's no object in the repository with that oid. The oid can be an Oid object, or an hexadecimal string.

oid in Repository

Returns True if there is an object in the Repository with that oid, False if there is not. The oid can be an Oid object, or an hexadecimal string.

The Object base type

The Object type is a base type, it is not possible to make instances of it, in any way.

It is the base type of the Blob, Tree, Commit and Tag types, so it is possible to check whether a Python value is an Object or not:

>>> from pygit2 import Object
>>> commit = repository.revparse_single('HEAD')
>>> print isinstance(commit, Object)
True

All Objects are immutable, they cannot be modified once they are created:

>>> commit.message = u"foobar"
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: attribute 'message' of '_pygit2.Commit' objects is not writable

Derived types (blobs, trees, etc.) don't have a constructor, this means they cannot be created with the common idiom:

>>> from pygit2 import Blob
>>> blob = Blob("data")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: cannot create '_pygit2.Blob' instances

New objects are created using an specific API we will see later.

This is the common interface for all Git objects:

pygit2.Object.oid

pygit2.Object.hex

pygit2.Object.type

pygit2.Object.read_raw

Blobs

A blob is just a raw byte string. They are the Git equivalent to files in a filesytem.

This is their API:

pygit2.Blob.data

Example, print the contents of the .gitignore file:

>>> blob = repo["d8022420bf6db02e906175f64f66676df539f2fd"]
>>> print blob.data
MANIFEST
build
dist

pygit2.Blob.size

Example:

>>> print blob.size
130

Creating blobs

There are a number of methods in the repository to create new blobs, and add them to the Git object database:

pygit2.Repository.create_blob

Example:

>>> oid = repo.create_blob('foo bar') # Creates blob from bytes string >>> blob = repo[oid] >>> blob.data 'foo bar'

pygit2.Repository.create_blob_fromworkdir

pygit2.Repository.create_blob_fromdisk

There are also some functions to calculate the oid for a byte string without creating the blob object:

pygit2.hash

pygit2.hashfile

Trees

A tree is a sorted collection of tree entries. It is similar to a folder or directory in a file system. Each entry points to another tree or a blob. A tree can be iterated, and partially implements the sequence and mapping interfaces.

Tree[name]

Return the TreeEntry object for the given name. Raise KeyError if there is not a tree entry with that name.

name in Tree

Return True if there is a tree entry with the given name, False otherwise.

len(Tree)

Return the number of entries in the tree.

iter(Tree)

Return an iterator over the entries of the tree.

pygit2.Tree.diff

Tree entries

pygit2.TreeEntry.name

pygit2.TreeEntry.oid

pygit2.TreeEntry.hex

pygit2.TreeEntry.filemode

Example:

>>> tree = commit.tree
>>> len(tree)                        # Number of entries
6

>>> for entry in tree:               # Iteration
...     print(entry.hex, entry.name)
...
7151ca7cd3e59f3eab19c485cfbf3cb30928d7fa .gitignore
c36f4cf1e38ec1bb9d9ad146ed572b89ecfc9f18 COPYING
32b30b90b062f66957d6790c3c155c289c34424e README.md
c87dae4094b3a6d10e08bc6c5ef1f55a7e448659 pygit2.c
85a67270a49ef16cdd3d328f06a3e4b459f09b27 setup.py
3d8985bbec338eb4d47c5b01b863ee89d044bd53 test

>>> entry = tree['pygit2.c']         # Get an entry by name
>>> entry
<pygit2.TreeEntry object at 0xcc10f0>

>>> blob = repo[entry.oid]           # Get the object the entry points to
>>> blob
<pygit2.Blob object at 0xcc12d0>

Creating trees

pygit2.Repository.TreeBuilder

pygit2.TreeBuilder.insert

pygit2.TreeBuilder.remove

pygit2.TreeBuilder.clear

pygit2.TreeBuilder.write

Commits

A commit is a snapshot of the working dir with meta informations like author, committer and others.

pygit2.Commit.author

pygit2.Commit.committer

pygit2.Commit.message

pygit2.Commit.message_encoding

pygit2.Commit.tree

pygit2.Commit.parents

pygit2.Commit.commit_time

pygit2.Commit.commit_time_offset

Signatures

The author and committer attributes of commit objects are Signature objects:

>>> commit.author
<pygit2.Signature object at 0x7f75e9b1f5f8>

pygit2.Signature.name

pygit2.Signature.email

pygit2.Signature.time

pygit2.Signature.offset

Creating commits

pygit2.Repository.create_commit

Commits can be created by calling the create_commit method of the repository with the following parameters:

>>> author = Signature('Alice Author', 'alice@authors.tld')
>>> committer = Signature('Cecil Committer', 'cecil@committers.tld')
>>> tree = repo.TreeBuilder().write()
>>> repo.create_commit(
... 'refs/heads/master', # the name of the reference to update
... author, committer, 'one line commit message\n\ndetailed commit message',
... tree, # binary string representing the tree object ID
... [] # list of binary strings representing parents of the new commit
... )
'#\xe4<u\xfe\xd6\x17\xa0\xe6\xa2\x8b\xb6\xdc35$\xcf-\x8b~'

Tags

A tag is a static label for a commit. See references for more information.

pygit2.Tag.name

pygit2.Tag.target

pygit2.Tag.tagger

pygit2.Tag.message

Creating tags

pygit2.Repository.create_tag