Checkout remote branch to a local (tracked banch)

[EugenMayer]

Looked through the issues and seen some similar questions, but iam not sure i found the right one.

If found:

• How to set upstream? #166 (comment)
• How to create local branch and track remote branch? #100

What i want is, i want to checkout a branch i know exists, but it could be, that it is yet not a local branch. Checking out local branches is easy ( so basically rather git switch ) but checking out remote branches seems to not work:

branch not found

  func CheckoutBranch(repository *gitlib.Repository, branchName string) error {
	localBranchLookup, err := repository.Branch(branchName)
	var branchRef plumbing.ReferenceName
	if err != nil {
		fmt.Print("Branch is not yet local, trying to fetch from remote")
		branchRef = plumbing.NewBranchReferenceName(branchName)
	} else {
		branchRef = localBranchLookup.Merge
	}

	worktree, err := repository.Worktree()
	if err != nil {
		return err
	}

	// Keep: true is important for performance reasons, to avoid vendor/github.com/go-git/go-git/v5/worktree.go:409
	// being called by reset, taking 10 seconds and more
	return worktree.Checkout(&gitlib.CheckoutOptions{Branch: branchRef, Keep: true})
}

worktree.Checkout fails with

reference not found

According to the issue i found i changed it to

func CheckoutBranch(repository *gitlib.Repository, branchName string) error {
	//
	//err = fetch(repository)
	//if err != nil {
	//	return err
	//}

	localBranchLookup, err := repository.Branch(branchName)
	if err != nil {
		fmt.Println("Branch is not yet local, trying to fetch from remoteName")
		remoteName := "origin"
		var remoteRef = plumbing.NewRemoteReferenceName(remoteName, branchName)
		var ref, err = repository.Reference(remoteRef, true)
		if err != nil {
			return err
		}

		var mergeRef = plumbing.ReferenceName(fmt.Sprintf("refs/heads/%s", branchName))
		err = repository.CreateBranch(&config.Branch{Name: branchName, Remote: remoteName, Merge: mergeRef})
		if err != nil {
			return err
		}
		var localRef = plumbing.ReferenceName(fmt.Sprintf("refs/heads/%s", branchName))
		return repository.Storer.SetReference(plumbing.NewHashReference(localRef, ref.Hash()))
	} else {
		localBranchRef := localBranchLookup.Merge
		worktree, err := repository.Worktree()
		if err != nil {
			return err
		}

		// Keep: true is important for performance reasons, to avoid vendor/github.com/go-git/go-git/v5/worktree.go:409
		// being called by reset, taking 10 seconds and more
		return worktree.Checkout(&gitlib.CheckoutOptions{Branch: localBranchRef, Keep: true})
	}
}

But got the same issue, just it happens at

var ref, err = repository.Reference(remoteRef, true)
if err != nil {
  return err
}

Wit again, reference not found.

What is the right way to do this? I cannot implement fetch due to #240, but if i do a manual git fetch -a on the repo beforehand, it should be the same result. Still it fails with reference not found

Thankful for any help

[dc-wc-2017]

my code is like this :

repo, err := git.PlainClone(repoDir, false, &git.CloneOptions{
    Auth: &githttp.BasicAuth{
        Username: authenticateUser,
        Password: authenticateToken,
    },
    URL: repoUrl,
})

if err != nil {
    if err != git.ErrRepositoryAlreadyExists {
        mylog.LogFatalExitByCheckingError(err)
    }
    fmt.Printf("Checked error: %v\n", err)
    // open this repository instead
    repo, err = git.PlainOpen(repoDir)
    mylog.LogFatalExitByCheckingError(err)
}

// refs/heads/<localBranchName>
localBranchReferenceName := plumbing.NewBranchReferenceName(branchName)
// refs/remotes/origin/<remoteBranchName>
remoteReferenceName := plumbing.NewRemoteReferenceName("origin", branchName)

err := repo.CreateBranch(&config.Branch{Name: branchName, Remote: "origin", Merge: localBranchReferenceName })
newReference := plumbing.NewSymbolicReference(localBranchReferenceName , remoteReferenceName)
err = repo.Storer.SetReference(newReference)
mylog.LogPanicByCheckingError(err)

[EugenMayer]

Thank you, this worked! Even though i fall back to checking out the branch on using the cli due to #238 creating a remote tracking branch this way works out fairly well.

[Ileriayo]

Tried this, and

1. It moves folders from one branch to the other, howbeit empty. This is not exactly the same effect as git checkout <branch-name> which just switches to a branch and sets it to track from origin (no extra folders).
2. Setting keep: true on checkout shows un-committed changes (i.e., on checkout to another branch, it shows the files from the other branch as deleted when you do a git status). Is there a way to keep ONLY changes made on local files?