Mercurial Hook - change a commit message pre commit

Question

Edit Made this basic hook to prevent branch name & commit message bugID mismatches. https://gist.github.com/2583189 So basically the idea is that the hook should append " BugID:xyz" to the end of the commit messages if the branch name is like bug_123, or feature_123. However I'm having problems finding out how to do this, as most examples of pretxncommit people don't want to mutate the changeset description. This is what I have so far. It updates .hg/commit.save with the right message, but this message is never transferred to the commit. It is however displayed in the default message box (tortoisehg) of the next commit. Perhaps pretxncommit isn't the right hook? Could I use a precommit hook, read the commit.save and repo['tip'].branch() file and change that, if so where would I fetch the branch name from? ``` # # Fogbugz automaticically add BugID:123 to commit messages based on branch names. # Your branch name must be in the format feature_123_description or bug_123_description # impo…

Accepted Answer

i think the problem here is that the `pretxncommit` hook is executed at a point where you can't really change anything anymore. And you can't really get the commit message at that point either, because it's not set on any context object accessible.

`repo['tip'].description()` doesn't refer to the changelog being committed but to old tip already committed, that would be `repo[None]`, but as some digging in the source revealed it's not the same context object that's being persisted, so it's no point in changing it.

the only way i could find would be to use an earlier hook - like `precommit` - and monkeypatch the `commitctx` method of the repository like this:

```
def precommit_hook(repo, **kwargs):

# keep a copy of repo.commitctx
    commitctx = repo.commitctx

def updatectx(ctx, error):

# check if `ctx.branch()` matches ...

# update commit text
        ctx._text += " ... additional text"

# call original
        return commitctx(ctx, error)

# monkeypatch the commit method
    repo.commitctx = updatectx
```

this way cou can access the context object just before it's committed.

Mercurial Hook - change a commit message pre commit

Solution

Problem