Using python-dulwich to load any version of a file from a local git repo

On Monday we are kicking off an innovation week (more to come on that topic) and I’ve devised a little project that includes nearly every buzzword I’m interested in.

I’m spending some time doing some technical spikes to see what is possible and I found a need to load a particular file from a git repo given the path and tree hash.

I grabbed my trusty python, dulwich (native python-git library) and gave it a shot. After a few minutes writing complicated looking recursive code I jumped over to irc where the friendly author pointed me to a convenience function that does what I needed.

Here is the short answer:

from dulwich.repo import Repo
from dulwich.object_store import tree_lookup_path

r = Repo('/Documents/projects/gitdep/rails')
def get_file(tree, path):
    (mode,sha) = tree_lookup_path(r.get_object,tree,path)
    return r[sha].data

tree = '7e7331fce169bbe1d6be71a30c1e1f7ab2e6ceba'
path = 'activemodel/examples/validations.rb'

print get_file(tree,path)

This gives me a rails validation file from last year. Nothing special about this file, I just find the rails git repo an interesting playground for git experimentation.

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