Re: [jgit-dev] question about commits/trees/parents

[Shawn Pearce <spearce@xxxxxxxxxxx>]

On Thu, May 3, 2012 at 5:00 AM, Markus Duft <markus.duft@xxxxxxxxxx> wrote:
>
> calling any getter on the parent (like getTree()) yields null or NPE... what am i doing wrong?

You need to make the RevWalk also parse the parent....

>    /**
>     * Searches for the commit object associated with the given Gerrit event. If no commit can be
>     * found, <code>null</code> is returned.
>     */
>    public RevCommit getCommit(GerritBaseChangeEvent e) {
>        GerritPatchset p = e.getPatchset();
>
>        if (p == null) {
>            return null;
>        }
>
>        String rev = p.getRevision();
>        try {
>            RevWalk walk = new RevWalk(repo);
>            return walk.parseCommit(getOidForRev(rev));

Instead do:

  RevCommit c = walk.parseCommit(getOidForRev(rev));
  walk.parseHeaders(c.getParent(0));
  return c;

To ensure it can offer good performance, RevWalks only parse the
minimum number of commits to answer the request. When you parsed the
one commit here, that only loaded that commit's tree and its parent
pointers. It didn't walk into the parents and load their trees, or
their parent pointers. So the only thing we know about the parent is
that it exists, and what its ObjectId is. We don't know what its tree
is until we at least parseHeaders on it.