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Bazaar to git - Odoo 8.0

Initializing a working copy

Use the easy-setup shell script:

curl -O https://raw.githubusercontent.com/odoo/odoo/master/odoo.py | python2

it will will ask a few questions and create a local copy.

Git concepts

Remotes

Remotes are "remote repositories" which can be fetched from and pushed to. Remotes can be listed with git remote1 and a local repository can have any number of remotes. The setup script creates 2 remotes:

odoo
the official repository and main branches, roughly corresponds to the old "mainline" branches in bazaar. You should never need to push to it, and by default your local copy is configured to forbid it.
odoo-dev
a grab-bag of development branches, you can push your work to it so other coworkers can work with you.

Branches

The working copy and each remote contain multiple branches. Local branches can be listed by git branch, remote branches can be listed with git branch -r. Both types can be listed with git branch -a.

Work is only possible on local branches, even though it's possible to check out a remote branch work on it will be lost.

Staging

bzr commit takes all alterations to the working copy and creates a commit from them. Git has an intermediate step called "staging". git commit will create a commit from what has been staged, not from the working copy2. Staging is done with git add. A commit with nothing staged is a null operation.

SHA1

Git has no sequential identifier, each commit is uniquely identified by a SHA (40 hexadecimal characters) roughly corresponding to a bazaar revision-id. Providing the full sha is rarely necessary, any unique leading substring is sufficient, e.g. dae86e will probably stand in for dae86e1950b1277e545cee180551750029cfe735.

Basic development workflow

  • update your remotes with git fetch --all
  • create your development branch with git checkout -b <branch_name> <source_branch>. For instance if you wanted to add support for full-text search in master you could use git checkout -b master-fts-xxx odoo/master
  • do your changes, stage them with git add and commit them with git commit
  • if your branch is long-lived, you may want to update it to its parent

    • update the remotes with git fetch --all
    • merge the remote branch into the local one with git merge --no-ff odoo/master
  • to push the branch to the development repository, use git push -u dev <branchname>, this will automatically create a branch called <branchname> on dev. Next time around you do not have to use -u
  • once the feature is done, create a pull request

Tasks

Converting your feature branches from bazaar

The readme has some instructions.

Viewing history: git log

git log fulfills the same role as bzr log and is fairly similar, with a few differences:

  • git log has no -r argument, its first argument (optional) is a revision spec
  • git log always operates on ranges, if a single commit is provided (via hash, tag, branch or other) it will list the specified commit and all of its ancestors. To see a single commit, use git show.
  • git log's second positional argument is a path (file or directory). Because both are optional, if both a revision and a file match the revision will be selected. It is recommended to use -- before a file path:

    git log -- filepath
    
  • git log will actually work if given a directory, instead of pegging the CPU forever
  • git log works with removed files or directories without having to provide a revision during which the file or directory still existed
  • git log has lots of options to customize the output, e.g. -p will display the changes to each file3, --name-status will list the changed files and how they changed SVN-style (with a M or D prefix), --name-only will just list the changed files, --stat generates a diffstat view, --grep filters by grepping on the commit message, …

Reverting uncommitted changes

  • If you have altered files which you want to revert, use git checkout -- <path>. To revert every file in the directory, use git checkout -- .
  • If you have staged a file and you want to unstage it, use git reset HEAD <file>. This will not revert the file's changes, the file will be marked as modified again

Diffing: git diff

git diff is fairly similar to bzr diff: it compares the working copy with stored content and can be restricted to a given file path. However:

  • git diff compares the working copy and the staging area, not the latest commit
  • git diff --staged compares the staging area and the latest commit
  • git diff HEAD ignores the staging area and compares the working copy with the latest commit. More generally git diff <commit> will diff the working copy and the specified commit
  • to diff between commits, simply pass the commit identifiers (no -r argument)
  • git diff --stat provides a diffstat-view of the diff, and can be combined with other flags. It can be used as an intermediate between git status and git status -s

Update to a previous revision

git checkout takes an arbitrary commit, the equivalent to bzr update -r<rev> is thus git checkout <rev>.

File from the past

bzr cat -r<revision> <filename> shows the file <filename> as it was at <revision>. The Git equivalent is git show <revision>:<filename>

Incorrect last commit: fix it

If the last commit has to be fixed a bit (error, missing data, incomplete/incorrect commit message) it can be fixed with git commit --amend. Instead of creating a new commit, it adds whatever is being committed to the previous commit.

Incorrect last commit: remove it

If the last commit has to be removed entirely (similar to bzr uncommit), use git reset HEAD~1.

Useful tips

Partial operations

checkout, add, commit, reset and stash can take a -p flag, which allows operating (staging, reverting, ...) on a subset of the file. It opens a UI allowing the selection (or not) of each patch hunk, and even the splitting of hunk if they're too big.

Allows reverting only part of the changes to a file, or cleanly splitting refactorings and fixes mixed in a file.

short status

The default status command is very verbose (though useful, it provides instructions for reverting things). The -s flag provides an SVN-like display instead with just a listing of files and A, M or D flags next to them. Each file can have 2 flags, the first is for the index (difference between the last commit and the index) and the and the second is for the working copy (difference between the index and the working copy).

checkout shortcut

checkout - will behave like cd -, it will switch to the previously checked-out branch/commit

[1] by default, git remote will only give the names of the various remotes. git remote -v will give the name and URL of each remote.
[2] the -a option will automatically stage modified and deleted files
[3] but only the changes performed by this actual commit, for a merge the merged changes are not considered part of the merge commit