flic.kr/p/6oP7x7 Version Control with Git

http://flic.kr/p/6oP7x7 Version Control with Git

Why track/manage revisions?

Backup: Undo or refer to old stuff http://git-scm.com/book/en/Git-Branching-Basic-Branching-and-Merging

Branch: Maintain old release while working on new http://git-scm.com/book/en/Git-Branching-Basic-Branching-and-Merging

Collaborate: Work in parallel with teammates http://git-scm.com/book/en/Distributed-Git-Distributed-Workflows

Version Control Systems (VCSs) Help you track/manage/distribute revisions Standard in modern development Examples: older – Revision Control System (RCS) – Concurrent Versions System (CVS) – Subversion (SVN) newer – Git Our focus

GitHub-User Perspective You Working Dir Local Repos GitHub Remote Repos

Let’s begin with an example You GitHub

Configure your Git client (Rails Tutorial 1.3.1) Install Git Check config info: git config --list user.name Scott Fleming user.email [email protected] Fix if necessary: git config --global user.name "John Doe" git config --global user.email [email protected]

Log into GitHub and create a repos (with add README option) You GitHub Remote Repos

git clone https://github.com/sdflem/comp4081 demo.git You Working Dir Local Repos GitHub Remote Repos

rails new comp4081 demo You Working Dir Local Repos GitHub Remote Repos

cd comp4081 demo git add -A git commit –m "Created Rails project skeleton" You Working Dir Local Repos GitHub Remote Repos

git push You Working Dir Local Repos GitHub Remote Repos

Questions to answer You Working Dir How organized? Local Repos What operations? GitHub Remote Repos

How the repos is organized http://git-scm.com/book/

How the repos is organized Commits (from oldest to newest; hashes as commit IDs) http://git-scm.com/book/

How the repos is organized Snapshot of all files at each commit http://git-scm.com/book/

How the repos is organized Branch (last commit) http://git-scm.com/book/

How commit works Before http://git-scm.com/book/

How commit works After http://git-scm.com/book/

Common Workflow 1. 2. 3. 4. 5. 6. 7. 8. Create temp local branch Make changes Checkout temp branch in local branch Edit/Add/Commit on temp branch Checkout master branch Merge with Pull to update master branch GitHub repos Merge temp branch with updated master Delete temp branch Push to update server repos

Organization with two branches

Organization with two branches Last commit of each branch

Organization with two branches Currently checked out branch

Common Workflow 1. 2. 3. 4. 5. 6. 7. 8. Create temp local branch Checkout temp branch Edit/Add/Commit on temp branch Checkout master branch Pull to update master branch Merge temp branch with updated master Delete temp branch Push to update server repos

How git branch works git branch testing Before

How git branch works git branch testing After

Common Workflow 1. 2. 3. 4. 5. 6. 7. 8. Create temp local branch Checkout temp branch Edit/Add/Commit on temp branch Checkout master branch Pull to update master branch Merge temp branch with updated master Delete temp branch Push to update server repos

How git checkout works git checkout testing Before

How git checkout works git checkout testing After

Common Workflow 1. 2. 3. 4. 5. 6. 7. 8. Create temp local branch Checkout temp branch Edit/Add/Commit on temp branch Checkout master branch Pull to update master branch Merge temp branch with updated master Delete temp branch Push to update server repos

How git commit works with multiple branches Edit some stuff git add -A git commit –m "blah" Before

How git commit works with multiple branches Edit some stuff git add -A git commit –m "blah" After

Common Workflow 1. 2. 3. 4. 5. 6. 7. 8. Create temp local branch Checkout temp branch Edit/Add/Commit on temp branch Checkout master branch Pull to update master branch Merge temp branch with updated master Delete temp branch Push to update server repos

How git checkout works git checkout master Before

How git checkout works git checkout master After

Common Workflow 1. 2. 3. 4. 5. 6. 7. 8. Create temp local branch Checkout temp branch Edit/Add/Commit on temp branch Checkout master branch Pull to update master branch Merge temp branch with updated master Delete temp branch Push to update server repos

How git pull works Someone else pushed git pull Before

How git pull works Someone else pushed git pull After

Common Workflow 1. 2. 3. 4. 5. 6. 7. 8. Create temp local branch Checkout temp branch Edit/Add/Commit on temp branch Checkout master branch Pull to update master branch Merge temp branch with updated master Delete temp branch Push to update server repos

How git merge works git merge testing Before

How git merge works git merge testing e2b92 After

Common Workflow 1. 2. 3. 4. 5. 6. 7. 8. Create temp local branch Checkout temp branch Edit/Add/Commit on temp branch Checkout master branch Pull to update master branch Merge temp branch with updated master Delete temp branch Push to update server repos

How to delete branches git branch -d testing e2b92 Before

How to delete branches git branch -d testing e2b92 After

Common Workflow 1. 2. 3. 4. 5. 6. 7. 8. Create temp local branch Checkout temp branch Edit/Add/Commit on temp branch Checkout master branch Pull to update master branch Merge temp branch with updated master Delete temp branch Push to update server repos

How git push works git push e2b92 Should update server repos (if no one else has pushed commits to master branch since last pull)

Tips git output contains lots of hints – git status is your friend! Merging may not be as easy as I showed – E.g.: Multiple collabs updated same parts of file – See Pro Git 3.2 Pull before starting temp branch Team communication important!

Pop Quiz 5 questions Update diagram in each – Commit nodes – Branch nodes Based on actions of Alice and Bob – Collaborating via GitHub repo

Start like this Scott Fleming GitHub master 11111 master Alice 11111 Bob SF 1

Question 1 Alice: – git clone https://github.com/whatever.git – cd whatever Bob: – git clone https://github.com/whatever.git – cd whatever (include the HEAD node)

Question 2 Alice: – git branch myfix – git checkout myfix (Alternatively) – git checkout -b myfix

Question 3 Alice: – rails generate scaffold User – git add -A – git commit -m "Added User" # 22222 Bob: – rails generate scaffold Micropost – git add -A – git commit -m "Added Micropost" # 33333

Question 4 Bob: – git push

Question 5 Alice: – git pull

Appendix

What if Alice did this: app/models/micropost.rb class Micropost ActiveRecord::Base validates :content, length: { maximum: 140 } end Bob did this: app/models/micropost.rb class Micropost ActiveRecord::Base validates :content, length: { maximum: 120 } end

What if Alice did this? master 33333 11111 22222 myfix git checkout master git merge myfix

git merge myfix Auto-merging app/models/micropost.rb Automatic merge failed; fix conflict and then commit result. app/models/micropost.rb class Micropost ActiveRecord::Base HEAD validates :content, length: { maximum: 140 } validates :content, length: { maximum: 120 } myfix end To resolve: Manually fix the file; git add and commit