gitpython and git diff

Question

I am looking to get only the diff of a file changed from a git repo. Right now, I am using gitpython to actually get the commit objects and the files of git changes, but I want to do a dependency analysis on only the parts of the file changed. Is there any way to get the git diff from git python? Or am I going to have to compare each of the files by reading line by line?

Walston

Answer 1

If you want to access the contents of the diff, try this:

repo = git.Repo(repo_root.as_posix())
commit_dev = repo.commit("dev")
commit_origin_dev = repo.commit("origin/dev")
diff_index = commit_origin_dev.diff(commit_dev)

for diff_item in diff_index.iter_change_type('M'):
    print("A blob:\n{}".format(diff_item.a_blob.data_stream.read().decode('utf-8')))
    print("B blob:\n{}".format(diff_item.b_blob.data_stream.read().decode('utf-8'))) 

This will print the contents of each file.

Byronbyrum

Excellent. This is the way to do it with the GitPython API, versus delegating directly to the Git CLI like Cairo's answer does. – Bullfighter

What about using this code with different branches? I dont want to be fixed on one branch (dev in your case) diff getting. – Nonviolence

you are awesoooooooome I was searching for this solution for 1 month!!! to make it more readable I shrink it to " diff = repo.commit(head1).diff(head2) " – Gaffney

Answer 2

You can use GitPython with the git command "diff", just need to use the "tree" object of each commit or the branch for that you want to see the diffs, for example:

repo = Repo('/git/repository')
t = repo.head.commit.tree
repo.git.diff(t)

This will print "all" the diffs for all files included in this commit, so if you want each one you must iterate over them.

With the actual branch it's:

repo.git.diff('HEAD~1')

Hope this help, regards.

Cedric

How can I find out the diff between the tree and head~1. They have similarities, but the latter has more diff entries. Seems that the latter includes the diff to the last commit. – Yapon

Answer 3

Git does not store the diffs, as you have noticed. Given two blobs (before and after a change), you can use Python's difflib module to compare the data.

Abortive

The repo I am working on only has one master branch. If I am trying to get two blobs, how do i get a second one to compare the before change? – Walston

Sorry, just another question. So beyond trying to get both the a blob and b blob and understanding what those are, will those blobs actually give me the content of the file changed? – Walston

@Walston if you're referring two blobs as in the diff of your working tree vs. the most recent commit, you should use repo.head.commit.diff(None) – Utas

This is the python3 version of the link – Yapon

Answer 4

If you're looking to recreate something close to what a standard git diff would show, try:

# cloned_repo = git.Repo.clone_from(
#     url=ssh_url,
#     to_path=repo_dir,
#     env={"GIT_SSH_COMMAND": "ssh -i " + SSH_KEY},
# ) 
for diff_item in cloned_repo.index.diff(None, create_patch=True):
    repo_diff += (
        f"--- a/{diff_item.a_blob.name}\n+++ b/{diff_item.b_blob.name}\n"
        f"{diff_item.diff.decode('utf-8')}\n\n"
        )

Twopenny

Answer 5

If you want to do git diff on a file between two commits this is the way to do it:

import git
   
repo = git.Repo()
path_to_a_file = "diff_this_file_across_commits.txt"
   
commits_touching_path = list(repo.iter_commits(paths=path_to_a_file))
   
print repo.git.diff(commits_touching_path[0], commits_touching_path[1], path_to_a_file)

This will show you the differences between two latest commits that were done to the file you specify.

Drudgery

Answer 6

repo.git.diff("main", "head~5")

result：

@@ -97,6 +97,25 @@ + </configuration> + + </plugin> + <plugin> - <groupId>org.codehaus.mojo</groupId> - <artifactId>findbugs-maven-plugin</artifactId> - <version>3.0.5</version> - <configuration> - <effort>Low</effort> - <threshold>Medium</threshold> 

Bathsheeb

Welcome to Stack Overflow! Please read How to Ask and edit your question to contain an explanation as to why this code would actually solve the problem at hand. Always remember that you're not only solving the problem, but are also educating the OP and any future readers of this post. – Recount

result： @@ -97,6 +97,25 @@ + </configuration> + + </plugin> + <plugin> - <groupId>org.codehaus.mojo</groupId> - <artifactId>findbugs-maven-plugin</artifactId> - <version>3.0.5</version> - <configuration> - <effort>Low</effort> - <threshold>Medium</threshold> – Clergyman

If you want to update, edit, don't comment. – Larceny

Answer 7

PyDriller +1

pip install pydriller

But with the new API:

Breaking API: ```
from pydriller import Repository

for commit in Repository('https://github.com/ishepard/pydriller').traverse_commits():
    print(commit.hash)
    print(commit.msg)
    print(commit.author.name)

    for file in commit.modified_files:
        print(file.filename, ' has changed')

Such

The author also wants a diff of the contents of the changes, not just which files changed. – Tycho

Answer 8

Here is how you do it

import git
repo = git.Repo("path/of/repo/")

# the below gives us all commits
repo.commits()

# take the first and last commit

a_commit = repo.commits()[0]
b_commit = repo.commits()[1]

# now get the diff
repo.diff(a_commit,b_commit)

Camaraderie

This code does not work. AttributeError: 'Repo' object has no attribute 'diff' and AttributeError: 'Repo' object has no attribute 'commits' – Changeup