Nodegit - How do I stage and commit a file? (simple example!)

Question

Using Node-git I just want to:

1. Open a repo (where a file has been written/updated)
2. Stage the file
3. Do commit

Using the git cli I would write something like this

cd repo    
git add file.js
git commit -m "Added file.js"

I'm trying to follow the examples here describing how to do it with nodegit but have a hard time following these lines of code:

.then(function() {
  return repo.refreshIndex();
})
.then(function(indexResult) {
  index = indexResult;
})
.then(function() {
  // this file is in the root of the directory and doesn't need a full path
  return index.addByPath(fileName);
})
.then(function() {
  // this file is in a subdirectory and can use a relative path
  return index.addByPath(path.join(directoryName, fileName));
})
.then(function() {
  // this will write both files to the index
  return index.write();
})
.then(function() {
  return index.writeTree();
})
.then(function(oidResult) {
  oid = oidResult;
  return nodegit.Reference.nameToId(repo, "HEAD");
})
.then(function(head) {
  return repo.getCommit(head);
})
.then(function(parent) {
  var author = nodegit.Signature.create("Scott Chacon",
    "[email protected]", 123456789, 60);
  var committer = nodegit.Signature.create("Scott A Chacon",
    "[email protected]", 987654321, 90);

  return repo.createCommit("HEAD", author, committer, "message", oid, [parent]);
})
.done(function(commitId) {
  console.log("New Commit: ", commitId);
});

Does it have to be so long? What are the roles of repo.refreshIndex(), index.write(), index.writeTree() etc. etc.? The API-docs is not so beginner friendly.

Thankful for enlightenment!

Answer 1

This is my first time working with this lib, but I figured I'd answer anyway. It's a lot easier to follow the flow if you swap out the promises for await. I commented with my basic understanding of what's going on.

  const repo = await git.Repository.open(localNotesDir);
  const index = await repo.refreshIndex(); // read latest
  const files = await repo.getStatus(); // get status of all files
  files.forEach(file => index.addByPath(file.path())); // stage each file
  await index.write(); // flush changes to index
  const changes = await index.writeTree(); // get reference to a set of changes
  const head = await git.Reference.nameToId(repo, "HEAD"); // get reference to the current state
  const parent = await repo.getCommit(head); // get the commit for current state
  const author = git.Signature.now("Scott Chacon", "[email protected]"); // build auth/committer
  const committer = git.Signature.now("Scott A Chacon", "[email protected]");
  // combine all info into commit and return hash
  const commitId = await repo.createCommit("HEAD", author, committer, "message", changes, [parent]);
  console.log('commitId', commitId);
  // changes and head are each oids. Read about them here:
  // https://hackage.haskell.org/package/gitlib-0.6.5/docs/Data-Git-Oid.html