How to create pull requests on Github

Pull Requests are the web-based version of sending software patches via email to code maintainers. They allow a person that has no access to a code repository to submit a code change to the repository administrator for review and 1-click merging.

Preparation

Create a free Github account at https://github.com
Login on Github with your credentials
Go to the homepage of the repository, for example https://github.com/sdsc/sdsc-summer-institute-2017

Small changes via Github.com

For small changes, like create a folder and upload a few files, or a quick fix on a previous file, you don’t even need to use the git command line client.

If you need to create a folder
- click on “Create new file”
- in the “Name your file…” box, insert: “yourfolder/README.md”
- in the README.md write a description of the content of the folder, you can use markdown syntax, (see the Markdown Cheatsheet )
- create a bullet list with description of the files you will be uploading next
- Click on “Propose new file”
- this will ask you to create a Pull Request, follow the prompts and make sure to confirm at the end that you want to create a Pull Request, you have to click twice on “Create Pull Request” buttons
If you want to upload files in the folder you just created, you need an additional step, if you want to upload to a folder already existing in the original repo, skip this:
- Go to the fork of the original repository that was created automatically under your account, for example: https://github.com/YOURUSERNAME/sdsc-summer-institute-2017
- Click on the dropdown “Branch” menu and look for the branch named patch-1, or patch-n if you have more.
Click on the “Upload files” button, select and upload all files, a few notes:
- do not upload zip archives
- do not upload large data files, Github is for code
- if you are uploading binary files like images, downgrade them to a small size
- this will ask you to create a Pull Request, follow the prompts and make sure to confirm at the end that you want to create a Pull Request, you have to click twice on “Create Pull Request” buttons
Check that your pull request appeared in the Pull Requests area of the repository, for example https://github.com/sdsc/sdsc-summer-institute-2017/pulls

Update a previously create Pull Request via Github.com

If the repository maintainer has some feedback on your Pull Request, you can update it to accomodate any requested change.

Go to the fork of the original repository that was created automatically under your account, for example: https://github.com/YOURUSERNAME/sdsc-summer-institute-2017
Click on the dropdown “Branch” menu and look for the branch named patch-1, or patch-n if you have more.
Now make changes to files or upload new files, then confirm and write a commit message from the web interface
Check that your changes appear as updates inside the Pull Request you created before, for example https://github.com/sdsc/sdsc-summer-institute-2017/pull/N where N is the number assigned to your Pull Request

Use the command line client

For more control and especially if you expect the repository maintainer to make changes to your Pull Request before merging it, better use git.

Click on the “Fork” button on the top right of the repository
Now you should be on the copy of the repository under your own account, for example https://github.com/YOURUSERNAME/sdsc-summer-institute-2017

Now open your terminal, if you never used git before, set it up with:

  $ git config --global user.name "Your Name"
  $ git config --global user.email "your@email.edu"

Now open your terminal and clone the repository with:

  git clone https://github.com/YOURUSERNAME/sdsc-summer-institute-2017

Enter in the repository folder
Create a branch to isolate your changes with:
```
  git checkout -b "add_XXXX_material"
```
Now create folders, modify files, you can use any text editor
Once you are done doing modifications, you can prepare them to be committed with, this adds everything inside the folder:
```
  git add my_folder
```
Generally better instead to add each file to make sure you don’t accidentally commit wrong files
```
  git add my_folder/aaa.txt my_folder/README.md
```
Then write this changes to history with a commit
```
  git commit -m "Added material about XXXX"
```
Push changes to Github
```
  git push -u origin add_XXXX_material
```
Now go to the homepage of the original repository, for example https://github.com/sdsc/sdsc-summer-institute-2017
There should be a yellow notice saying that it detected a recently pushed branch, click on “Compare and Pull Request”
Add a description
Confirm with the green “Create Pull Request” button

In case you want to update your Pull Request, repeat the steps of git add, git commit and git push, any changes will be reflected inside the pull request.