Get the default branch of a remote repository with JGit

Question

I am working on a Git client, and right now I am trying to implement the checkout of a specific branch. I have a combo box that I populate with branch names, and I would like to find out which branch is the default, so that I can set it as the preselected item in the combo box when connecting to a valid Git repository.

I am listing all the remote branches as you can see below, but I cannot figure out which is the default one.

Map<String, Ref> callAsMap = Git.lsRemoteRepository()
    .setRemote("https://github.com/example")
    .setCredentialsProvider(credentialsProvider)
    .callAsMap();

So, is there a way (standard or "hacky") to detect which Ref object represents the default branch? And how can I get its name?

You should be able to chain a `.get("HEAD")` after this for the default-branch. — Ben, May 23 '18 at 06:21
Tried this, but how can I find out the name of the default branch? If I invoke `getName()` the answer is `HEAD`. But I expected something like `master`, because that's the name of one of my repos' default branch. — Sorin Adrian Carbunaru, May 23 '18 at 06:24
If you feel an answer solved the problem, please mark it as 'accepted' by clicking the green checkmark. This helps keep the focus on older posts which still don't have answers. — Rüdiger Herrmann, Jun 04 '18 at 18:22
Hm, I felt like none solved the problem. But in the end, it seems that it cannot really detect which is the default, because there might not be a default advertised, right? — Sorin Adrian Carbunaru, Jun 05 '18 at 12:17
@SorinAdrianCarbunaru Did you get any solution for getting the default branch using Jgit — Swapnil Gangrade, Sep 29 '21 at 10:03
Um, this was quite a long time ago, but it doesn't seem I found a solution. I just worked around this issue for my use case. — Sorin Adrian Carbunaru, Oct 26 '21 at 07:02
@SorinAdrianCarbunaru what is your workaround? can you share some details? — Swapnil Gangrade, Nov 15 '21 at 05:24

Rüdiger Herrmann · Answer 1 · 2018-05-23T08:50:05.940

2

Repository::getFullBranch returns the current branch of the local repository.

To get the default branch of a remote repository, you need to ask for its HEAD ref. The map that is returned by the snippet that you posted should contain an entry with key HEAD and (if I'm not mistaken) a value that denotes the name of the default branch.

If HEAD refers to an object id, you could obtain a list of all remote refs with repository.getRefDatabase().getRefs(Constants.R_REMOTES) to look up the HEAD id. This approach may be inaccurate as multiple refs could point to the same object id.

Note that it is not required for a remote repository to advertise a default branch.

See also these posts for how C-Git finds the default branch: git - how to get default branch? and What determines default branch after "git clone"?)

edited May 23 '18 at 08:50

answered May 23 '18 at 07:37

Rüdiger Herrmann

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Hmmm, I already tried that yesterday, and I remember the name for `HEAD` was simply a hashcode. I'd like to find the "real" name, such as `master` or `dev`... – Sorin Adrian Carbunaru May 23 '18 at 08:36
Hm, that's what I feared. Please see my edited answer. – Rüdiger Herrmann May 23 '18 at 08:50

score 0 · Answer 2 · answered Aug 09 '22 at 18:00

After the chain with .get("HEAD"), if it is a symbolic link, you can chain it with .getTarget().getName() to "extract" its name e.g.

Map<String, Ref> callAsMap = Git.lsRemoteRepository()
.setRemote("https://github.com/example")
.setCredentialsProvider(credentialsProvider)
.callAsMap().get("HEAD").getTarget().getName()

Source: https://www.eclipse.org/lists/jgit-dev/msg03320.html

Get the default branch of a remote repository with JGit

2 Answers2