GitPython provides object model access to your git repository. This tutorial is composed of multiple sections, each of which explains a real-life usecase.
Initialize a Repo object¶
The first step is to create a Repo object to represent your repository:
from git import * repo = Repo("/Users/mtrier/Development/git-python") assert repo.bare == False
In the above example, the directory /Users/mtrier/Development/git-python is my working repository and contains the .git directory. You can also initialize GitPython with a bare repository:
repo = Repo.init("/var/git/git-python.git", bare=True) assert repo.bare == True
A repo object provides high-level access to your data, it allows you to create and delete heads, tags and remotes and access the configuration of the repository:
repo.config_reader() # get a config reader for read-only access repo.config_writer() # get a config writer to change configuration
Query the active branch, query untracked files or whether the repository data has been modified:
repo.is_dirty() False repo.untracked_files ['my_untracked_file']
Clone from existing repositories or initialize new empty ones:
cloned_repo = repo.clone("to/this/path") new_repo = Repo.init("path/for/new/repo")
Archive the repository contents to a tar file:
Repo instances are powered by its object database instance which will be used when extracting any data, or when writing new objects.
The type of the database determines certain performance characteristics, such as the quantity of objects that can be read per second, the resource usage when reading large data files, as well as the average memory footprint of your application.
The GitDB is a pure-python implementation of the git object database. It is the default database to use in GitPython 0.3. Its uses less memory when handling huge files, but will be 2 to 5 times slower when extracting large quantities small of objects from densely packed repositories:
repo = Repo("path/to/repo", odbt=GitDB)
The git command database uses persistent git-cat-file instances to read repository information. These operate very fast under all conditions, but will consume additional memory for the process itself. When extracting large files, memory usage will be much higher than the one of the GitDB:
repo = Repo("path/to/repo", odbt=GitCmdObjectDB)
References are the tips of your commit graph from which you can easily examine the history of your project:
heads = repo.heads master = heads.master # lists can be accessed by name for convenience master.commit # the commit pointed to by head called master master.rename("new_name") # rename heads
Tags are (usually immutable) references to a commit and/or a tag object:
tags = repo.tags tagref = tags tagref.tag # tags may have tag objects carrying additional information tagref.commit # but they always point to commits repo.delete_tag(tagref) # delete or repo.create_tag("my_tag") # create tags using the repo for convenience
A symbolic reference is a special case of a reference as it points to another reference instead of a commit:
head = repo.head # the head points to the active branch/ref master = head.reference # retrieve the reference the head points to master.commit # from here you use it as any other reference
Access the reflog easily:
log = master.log() log # first (i.e. oldest) reflog entry log[-1] # last (i.e. most recent) reflog entry
For more information on the reflog, see the RefLog type’s documentation.
You can easily create and delete reference types or modify where they point to:
repo.delete_head('master') # delete an existing head master = repo.create_head('master') # create a new one master.commit = 'HEAD~10' # set branch to another commit without changing index or working tree
Create or delete tags the same way except you may not change them afterwards:
new_tag = repo.create_tag('my_tag', 'my message') repo.delete_tag(new_tag)
Change the symbolic reference to switch branches cheaply ( without adjusting the index or the working copy ):
new_branch = repo.create_head('new_branch') repo.head.reference = new_branch
An Object is anything storable in git’s object database. Objects contain information about their type, their uncompressed size as well as the actual data. Each object is uniquely identified by a binary SHA1 hash, being 20 bytes in size.
Git only knows 4 distinct object types being Blobs, Trees, Commits and Tags.
In Git-Python, all objects can be accessed through their common base, compared and hashed. They are usually not instantiated directly, but through references or specialized repository functions:
hc = repo.head.commit hct = hc.tree hc != hct hc != repo.tags hc == repo.head.reference.commit
Common fields are:
hct.type 'tree' hct.size 166 hct.hexsha 'a95eeb2a7082212c197cabbf2539185ec74ed0e8' hct.binsha 'binary 20 byte sha1'
Index Objects are objects that can be put into git’s index. These objects are trees, blobs and submodules which additionally know about their path in the filesystem as well as their mode:
hct.path # root tree has no path '' hct.trees.path # the first subdirectory has one though 'dir' htc.mode # trees have the mode of a linux directory 040000 '%o' % htc.blobs.mode # blobs have a specific mode though comparable to a standard linux fs 100644
Access blob data (or any object data) directly or using streams:
htc.blobs.data_stream.read() # stream object to read data from htc.blobs.stream_data(open("blob_data", "w")) # write data to given stream
The Commit object¶
Commit objects contain information about a specific commit. Obtain commits using references as done in Examining References or as follows.
Obtain commits at the specified revision:
repo.commit('master') repo.commit('v0.1') repo.commit('HEAD~10')
Iterate 100 commits:
If you need paging, you can specify a number of commits to skip:
repo.iter_commits('master', max_count=10, skip=20)
The above will return commits 21-30 from the commit list.:
headcommit = repo.head.commit headcommit.hexsha '207c0c4418115df0d30820ab1a9acd2ea4bf4431' headcommit.parents (<git.Commit "a91c45eee0b41bf3cdaad3418ca3850664c4a4b4">,) headcommit.tree <git.Tree "563413aedbeda425d8d9dcbb744247d0c3e8a0ac"> headcommit.author <git.Actor "Michael Trier <email@example.com>"> headcommit.authored_date # seconds since epoch 1256291446 headcommit.committer <git.Actor "Michael Trier <firstname.lastname@example.org>"> headcommit.committed_date 1256291446 headcommit.message 'cleaned up a lot of test information. Fixed escaping so it works with subprocess.'
Note: date time is represented in a seconds since epoch format. Conversion to human readable form can be accomplished with the various time module methods:
import time time.asctime(time.gmtime(headcommit.committed_date)) 'Wed May 7 05:56:02 2008' time.strftime("%a, %d %b %Y %H:%M", time.gmtime(headcommit.committed_date)) 'Wed, 7 May 2008 05:56'
You can traverse a commit’s ancestry by chaining calls to parents:
The above corresponds to master^^^ or master~3 in git parlance.
The Tree object¶
A tree records pointers to the contents of a directory. Let’s say you want the root tree of the latest commit on the master branch:
tree = repo.heads.master.commit.tree <git.Tree "a006b5b1a8115185a228b7514cdcd46fed90dc92"> tree.hexsha 'a006b5b1a8115185a228b7514cdcd46fed90dc92'
Once you have a tree, you can get the contents:
tree.trees # trees are subdirectories [<git.Tree "f7eb5df2e465ab621b1db3f5714850d6732cfed2">] tree.blobs # blobs are files [<git.Blob "a871e79d59cf8488cac4af0c8f990b7a989e2b53">, <git.Blob "3594e94c04db171e2767224db355f514b13715c5">, <git.Blob "e79b05161e4836e5fbf197aeb52515753e8d6ab6">, <git.Blob "94954abda49de8615a048f8d2e64b5de848e27a1">]
Its useful to know that a tree behaves like a list with the ability to query entries by name:
tree == tree['dir'] # access by index and by sub-path <git.Tree "f7eb5df2e465ab621b1db3f5714850d6732cfed2"> for entry in tree: do_something_with(entry) blob = tree blob.name 'file' blob.path 'dir/file' blob.abspath '/Users/mtrier/Development/git-python/dir/file' >>>tree['dir/file'].binsha == blob.binsha
There is a convenience method that allows you to get a named sub-object from a tree with a syntax similar to how paths are written in an unix system:
tree/"lib" <git.Tree "c1c7214dde86f76bc3e18806ac1f47c38b2b7a30"> tree/"dir/file" == blob
You can also get a tree directly from the repository if you know its name:
repo.tree() <git.Tree "master"> repo.tree("c1c7214dde86f76bc3e18806ac1f47c38b2b7a30") <git.Tree "c1c7214dde86f76bc3e18806ac1f47c38b2b7a30"> repo.tree('0.1.6') <git.Tree "6825a94104164d9f0f5632607bebd2a32a3579e5">
As trees only allow direct access to their direct entries, use the traverse method to obtain an iterator to traverse entries recursively:
tree.traverse() <generator object at 0x7f6598bd65a8> for entry in tree.traverse(): do_something_with(entry)
If tree’s return Submodule objects, they will assume that they exist at the current head’s commit. The tree it originated from may be rooted at another commit though, which has to be told to the Submodule object using its set_parent_commit(my_commit) method.
The Index Object¶
The git index is the stage containing changes to be written with the next commit or where merges finally have to take place. You may freely access and manipulate this information using the IndexFile Object:
index = repo.index
Access objects and add/remove entries. Commit the changes:
for stage, blob in index.iter_blobs(): do_something(...) # Access blob objects for (path, stage), entry in index.entries.iteritems: pass # Access the entries directly index.add(['my_new_file']) # add a new file to the index index.remove(['dir/existing_file']) new_commit = index.commit("my commit message")
Create new indices from other trees or as result of a merge. Write that result to a new index file:
tmp_index = Index.from_tree(repo, 'HEAD~1') # load a tree into a temporary index merge_index = Index.from_tree(repo, 'base', 'HEAD', 'some_branch') # merge two trees three-way merge_index.write("merged_index")
Remotes are used as alias for a foreign repository to ease pushing to and fetching from them:
test_remote = repo.create_remote('test', 'git@server:repo.git') repo.delete_remote(test_remote) # create and delete remotes origin = repo.remotes.origin # get default remote by name origin.refs # local remote references o = origin.rename('new_origin') # rename remotes o.fetch() # fetch, pull and push from and to the remote o.pull() o.push()
You can easily access configuration information for a remote by accessing options as if they where attributes:
Change configuration for a specific remote only:
Submodules can be conveniently handled using the methods provided by Git-Python, and as an added benefit, Git-Python provides functionality which behave smarter and less error prone than its original c-git implementation, that is Git-Python tries hard to keep your repository consistent when updating submodules recursively or adjusting the existing configuration.
In the following brief example, you will learn about the very basics, assuming you operate on the Git-Python repository itself:
>>> repo = Repo('path/to/git-python/repository') >>> sms = repo.submodules [git.Submodule(name=gitdb, path=lib/git/ext/gitdb, url=git://github.com/gitpython-developers/GitPython.git, branch=master)] >>> sm = sms >>> sm.name 'gitdb' >>> sm.module() # The module is the actual repository referenced by the submodule <git.Repo "<prefix>/git-python/lib/git/ext/gitdb/.git"> >>> sm.module_exists() True >>> sm.abspath == sm.module().working_tree_dir # the submodule's absolute path is the module's path True >>> sm.hexsha # Its sha defines the commit to checkout '2ddc5bad224d8f545ef3bb2ab3df98dfe063c5b6' >>> sm.exists() # yes, this submodule is valid and exists True >>> sm.config_reader().get_value('path') == sm.path # read its configuration conveniently True >>> sm.children() # query the submodule hierarchy [git.Submodule(name=async, path=ext/async, url=git://github.com/gitpython-developers/async.git, branch=master)]
In addition to the query functionality, you can move the submodule’s repository to a different path <move(...)>, write its configuration <config_writer().set_value(...)>, update its working tree <update(...)>, and remove and add them <remove(...), add(...)>.
If you obtained your submodule object by traversing a tree object which is not rooted at the head’s commit, you have to inform the submodule about its actual commit to retrieve the data from by using the set_parent_commit(...) method.
The special RootModule type allows you to treat your master repository as root of a hierarchy of submodules, which allows very convenient submodule handling. Its update(...) method is reimplemented to provide an advanced way of updating submodules as they change their values. The update method will track changes and make sure your working tree and submodule checkouts stay consistent, which is very useful in case submodules get deleted or added to name just two of the handled cases.
Additionally, Git-Python adds functionality to track a specific branch, instead of just a commit. Supported by customized update methods, you are able to automatically update submodules to the latest revision available in the remote repository, as well as to keep track of changes and movements of these submodules. To use it, set the name of the branch you want to track to the submodule.$name.branch option of the .gitmodules file, and use Git-Python update methods on the resulting repository with the to_latest_revision parameter turned on. In the latter case, the sha of your submodule will be ignored, instead a local tracking branch will be updated to the respective remote branch automatically. The resulting behaviour is much like the one of svn::externals, which can be useful in times.
Obtaining Diff Information¶
Diffs can generally be obtained by subclasses of Diffable as they provide the diff method. This operation yields a DiffIndex allowing you to easily access diff information about paths.
Diffs can be made between the Index and Trees, Index and the working tree, trees and trees as well as trees and the working copy. If commits are involved, their tree will be used implicitly:
hcommit = repo.head.commit idiff = hcommit.diff() # diff tree against index tdiff = hcommit.diff('HEAD~1') # diff tree against previous tree wdiff = hcommit.diff(None) # diff tree against working tree index = repo.index index.diff() # diff index against itself yielding empty diff index.diff(None) # diff index against working copy index.diff('HEAD') # diff index against current HEAD tree
The item returned is a DiffIndex which is essentially a list of Diff objects. It provides additional filtering to ease finding what you might be looking for:
for diff_added in wdiff.iter_change_type('A'): do_something_with(diff_added)
Use the diff framework if you want to implement git-status like functionality.
- A diff between the index and the commit’s tree your HEAD points to
- use repo.index.diff(repo.head)
- A diff between the index and the working tree
- use repo.index.diff(None)
- A list of untracked files
- use repo.untracked_files
To switch between branches, you effectively need to point your HEAD to the new branch head and reset your index and working copy to match. A simple manual way to do it is the following one:
repo.head.reference = repo.heads.other_branch repo.head.reset(index=True, working_tree=True)
The previous approach would brutally overwrite the user’s changes in the working copy and index though and is less sophisticated than a git-checkout for instance which generally prevents you from destroying your work. Use the safer approach as follows:
repo.heads.master.checkout() # checkout the branch using git-checkout repo.heads.other_branch.checkout()
Using git directly¶
In case you are missing functionality as it has not been wrapped, you may conveniently use the git command directly. It is owned by each repository instance:
git = repo.git git.checkout('head', b="my_new_branch") # default command git.for_each_ref() # '-' becomes '_' when calling it
The return value will by default be a string of the standard output channel produced by the command.
Keyword arguments translate to short and long keyword arguments on the commandline. The special notion git.command(flag=True) will create a flag without value like command --flag.
If None is found in the arguments, it will be dropped silently. Lists and tuples passed as arguments will be unpacked recursively to individual arguments. Objects are converted to strings using the str(...) function.
Git Command Debugging and Customization¶
Using environment variables, you can further adjust the behaviour of the git command.
- If set to non-0, all executed git commands will be printed to stdout.
- if set to full, the executed git command will be printed along with its output.
- If set, it should contain the full path to the git executable, e.g. c:\Program Files (x86)\Git\bin\git.exe on windows or /usr/bin/git on linux.
And even more ...¶
There is more functionality in there, like the ability to archive repositories, get stats and logs, blame, and probably a few other things that were not mentioned here.
Check the unit tests for an in-depth introduction on how each function is supposed to be used.