= Git =
[[TOC]]
Sahana Eden uses the Git DVCS & hosts active branches on [https://github.com GitHub]
== Developer Workflow ==
=== Fork a fresh Branch ===
* Sign-up for an account on [https://github.com GitHub]
  * So that you can contribute code back to the project you will need an SSH public key. There is on-line help at github (select Beginner - Set Up Git and then scroll down to Set Up SSH Keys) 
* Fork the Eden Branch: https://github.com/flavour/eden/fork_select
* Use Git to clone this down to your PC:
{{{
cd web2py/applications
git clone git@github.com:mygitusername/eden.git
cd eden
git remote add upstream git://github.com/flavour/eden.git
}}}

=== Ongoing Coding ===
We suggest adopting the [http://blog.hasmanythrough.com/2008/12/18/agile-git-and-the-story-branch-pattern Story Branch] pattern, which allows squashing commits in order to keep the main Trunk as clean as possible
{{{
cd <mybranch>
# Update your working directory with latest code from Trunk
git pull upstream master
git checkout -b <mystory>
# Write Code
git commit -am "My Story"
# Quick review of code (no test code left in, etc)
git diff master
# Merge latest Trunk
git checkout master
git pull # to get any merges, pulls or edits which you may have done on your GitHub branch
git pull upstream master
git checkout <mystory>
# Squash commits to as few as possible to keep revision history clean & make it easier to review the work
git rebase -i master
# Push to your branch on GitHub
git checkout master
git merge <mystory>
git push
# Cleanup
git branch -d <mystory>
}}}

Once you have pushed to your branch on GitHub, you will likely want this to be merged with Trunk - this should be done via a Pull Request. This is done on GitHub:
* https://github.com/<username>/eden/pull/new/master
=== Resolving Merge Conflicts ===
If you encounter conflicts during the rebase, the conflicts will be tagged in the files with:
{{{
<<<<<<< HEAD
# Commits from Trunk
=======
# Commits from <mystory>
>>>>>>> "My Story"
}}}
You can correct these conflict in your code text editor, then add them andcontinue the rebase:
{{{
git add -u
git rebase --continue
}}}

You can create the .THIS & .OTHER files using:
{{{
git show :2:file.txt > file.txt.THIS
git show :3:file.txt > file.txt.OTHER
}}}
You can use the changes to a file in the remote branch (theirs / OTHER):
{{{
git checkout --theirs filename.c
git add filename.c
git commit 
}}}
...or the changes to a file in your local branch (ours / THIS):
{{{
git checkout --ours filename.c
git add filename.c
git commit
}}}
...or the changes to ALL files in the remote branch (theirs / OTHER):
{{{
git checkout --theirs . # checkout our local version of all files
git add -u             # mark all conflicted files as merged
git commit             # commit the merge
}}}
Or the changes to ALL files in your local branch (ours / THIS)
{{{
git checkout --ours . # checkout our local version of all files
git add -u            # mark all conflicted files as merged
git commit            # commit the merge
}}}
Although on Windows this seems by default to produce UTF-16 files! ('UCS-2 Little Endian'). A script to make this process easier for Windows users is attached: [http://eden.sahanafoundation.org/attachment/wiki/DeveloperGuidelines/Git/merge.cmd merge.cmd]

=== Reverting to last committed code ===
If you want to throw away all uncommitted changes (i.e. '{{{bzr revert}}}'), then:
{{{
git reset --hard HEAD
}}}

=== Creating a 2nd branch ===
If you wish to have multiple separate branches to work on, you can run these as separate web2py applications
* Create a fresh Clone:
{{{
cd web2py/applications
git clone git@github.com:flavour/eden.git <mybranch>
}}}
* Setup a new Repository on GitHub: https://github.com/repositories/new
* Edit {{{.git/config}}}:
{{{
[remote "origin"]
    fetch = +refs/heads/*:refs/remotes/origin/*
    url = git@github.com:<mygitusername>/<mybranch>.git
}}}
* Push to GitHub:
{{{
cd <mybranch>
git push -u origin master
git remote add upstream git://github.com/flavour/eden.git
}}}

=== Using Patches ===
If you have made changes to one branch & wish to backport them to another branch, then this is done most easily using a Patch:
* http://ariejan.net/2009/10/26/how-to-create-and-apply-a-patch-with-git
== Developer Configuration ==
{{{
git config --global user.name "Your Name"
git config --global user.email your@email.com
git config --global github.user yourgithubusername
git config --global github.token yourtoken
git config --global core.editor "'C:/Program Files (x86)/Notepad++/notepad++.exe' -multiInst -notabbar -nosession -noPlugin"
git config --global merge.tool diffmerge
git config --global diff.tool diffmerge
git config --global difftool.diffmerge.cmd 'C:/Program Files (x86)/Git/etc/wrappers/git-diff-diffmerge-wrapper.sh' "$LOCAL" "$REMOTE"
git config --global difftool.prompt false
git config --global merge.tool diffmerge
git config --global mergetool.diffmerge.cmd 'C:/Program Files (x86)/Git/etc/wrappers/git-merge-diffmerge-wrapper.sh' "$PWD/$LOCAL" "$PWD/$BASE" "$PWD/$REMOTE" "$PWD/$MERGED"
git config --global mergetool.prompt false
git config --global mergetool.trustExitCode false
git config --global mergetool.keepBackup false
}}}

An alternative to diffmerge is Perforce's free P4V:
* http://danlimerick.wordpress.com/2011/06/19/git-for-window-tip-use-p4merge-as-mergetool/
=== Windows ===
Install [http://sourceforge.net/projects/console/ Console] & [http://www.sourcegear.com/diffmerge/downloads.php Diffmerge] & [http://markembling.info/2009/09/my-ideal-powershell-prompt-with-git-integration configure Powershell].
=== Developer Tools ===
{{{.gitattributes}}} runs {{{version.py}}} to update the {{{VERSION}}} file on commit

Possibly we could add a pre-commit hook to run tests, e.g. based on http://tech.yipit.com/2011/11/16/183772396/ or http://blog.penzilla.net/2011/09/git-pre-commit-hook-for-python-now-with.html

=== Notifications ===
You can subscribe to commits via RSS, e.g. to subscribe to Trunk, use:
* https://github.com/flavour/eden/commits/master.atom

If you wish to receive email notification of commits, then you can use an Email to RSS service like:
* http://www.feedmyinbox.com
* http://blogtrottr.com

== Alternate Developer Workflow ==
This is an alternate woerkflow which we shoudl deprecate after seeing whether anythign should be moved up
 * Make sure your work is fully tested.
 * Tell git about any new files you've added. If you've added a new directory, you can just add the files in the directory and git will add the directory too. (Do "git help add" for a description of how to use the bzr add command.)
{{{
git add filename...
}}}
 * Commit your changes -- this records them in your local git repository. Provide a message that describes what the change is for. If it fixes a bug, include the ticket number.
{{{
git commit -a -m "Describe your change here."
}}}
 * It is really important, that the forked and the main eden repositorys are in sync here as we want to avoid merge-conflicts. To do that we need a branch of the eden master-repository:
{{{
 * Make sure that you are in the Eden directory here!
git remote add upstream git://github.com/flavour/eden.git
git fetch upstream
}}}
 * Now you have a branch of the original Eden repository. If you want to update your master-branch, you can fetch it again and merge both branches:
{{{
git fetch upstream
git merge upstream/master
}}}
 * Solve the conflicts if there were any
 * Finally commit the merged version, push it to GitHub and send a Pull-Request on the GitHub site:
{{{
git status
... add missing files ...
git commit -a -m "Some message"
git push
}}}

== Resources ==
* Community Book: http://book.git-scm.com
* Tips & Tricks: http://gitready.com

== History ==
=== Why? ===
Sahana Eden has decided to move from !Bzr/LaunchPad to !Git/GitHub
* The current repository is huge & bloated, taking too long to download.
* Even simple changes take an age to Pull down to servers
* Web2py no longer supports !Bzr/LaunchPad, so we want to be able to maintain a common tool to work with both repositories.
* New developers are likely to be more familiar with !Git/GitHub

=== How? ===
The preferred approach is to have a clean repository, in order to get the maximum benefit from the migration...although it is technically possible to [http://fearthecowboy.com/2011/04/29/converting-bazaar-repositories-to-git/ migrate the commit history]. Commit History will instead be maintained on the !LaunchPad site as an archive

==== Migrating existing Branches ====
Merge branch with trunk using normal Bzr tools

Assuming that you have already [https://github.com/flavour/eden/fork_select forked Eden Trunk], then you will need to create a new repository manually for additional branches, as you cannot [http://bitdrift.com/post/4534738938/fork-your-own-project-on-github fork your own project on GitHub]:
* https://github.com/repositories/new
{{{
cd web2py/applications
git clone git@github.com:flavour/eden.git <mybranch>2
}}}
* Move {{{.git}}} & {{{.gitignore}}} from <mybranch>2 to <mybranch>
* Delete the rest of <mybranch>2
* Edit {{{.git/config}}}:
{{{
[remote "origin"]
    fetch = +refs/heads/*:refs/remotes/origin/*
    url = git@github.com:<mygitusername>/<mybranch>.git
}}}
* Create the initial repo for this new branch
{{{
cd <mybranch>
git add .
git commit -am "Initial Git version of My branch"
git push -u origin master
git remote add upstream git://github.com/flavour/eden.git
}}}