Mastering Git Pull: An Expert Guide to Fetching and Merging Branches

Earlier we covered the basics of how git pull integrates upstream changes… Now let‘s dive into some more advanced pull techniques for full-stack developers managing complex Git workflows.

To Rebase or To Merge: Weighing Different Pull Strategies

By default, git pull merges commits from the fetched branch directly into the target branch via a merge commit. But an alternative approach is to rebase the changes instead.

So what is rebasing and when should you use it?

An Introduction to Git Rebasing

Rebasing is the process of taking a sequence of commits…

Comparing Merge and Rebase Pull Approaches

Let‘s look at how each pull method affects the final commit history…

Customizing Pull to Always Rebase

Rather than choosing merge vs rebase manually for each pull, we can configure pull to rebase by default:

git config --global pull.rebase true

Now all pulls will replay commits onto the base branch with --rebase instead of --merge.

Automating Quality Control with Pull Requests

Beyond directly running git pull from branches, another way to bring in upstream changes is through pull requests (PRs). PRs provide code review and quality control between merging branches.

Using PR Checks to Prevent Broken Builds

Unlike raw git pull commands, with PRs we can run automated checks before allowing upstream merges:

Some examples include:

• Unit test verification
• Static analysis like linters
• Checking for compile errors

Hooking PR Pipelines into CI/CD Workflows

An advantage of PR-based workflows is each branch acts as a staging environment for validating changes…

Special Considerations for Pulling with Submodules

Git submodules allow embedding external repositories inside a parent repository…

While useful, submodules pose unique challenges when pulling upstream changes.

Fetching the Latest Commit SHAs

The first step is always to fetch the latest SHA references of the submodule projects:

git submodule update --remote

This doesn‘t merge updates but retrieves pointers for the child repos.

Updating Submodules to Match SHAs

Once the SHAs are fetched, we can pull changes within each submodule:

git submodule foreach git pull origin master

This will update all submodules to align with the SHAs from the parent repo.

Pitfalls to Avoid

Without running the submodule update commands, pulls in the parent repository can leave projects out of sync:

Troubleshooting Tricky Git Pull Scenarios

Like any complex Git workflow, there are bound to be tricky situations and outright failures from time to time. Here are some battle-tested troubleshooting techniques…

Recovering from a Bad Pull with Reflog

In case you pull changes that break the codebase, Git provides an escape hatch to revert back in time…

<introduce git reflog, example undoing bad pull>

Resolving Merge Conflicts

The bane of any Git user is running into merge conflicts during pull:

Auto-merging main.py
CONFLICT (content): Merge conflict in main.py
Automatic merge failed; fix conflicts and then commit the result.

Here are methods for troubleshooting resolution:

• Review conflict markers >>> and <<<
• Temporarily revert problematic commits
• Lock down upstream branch until conflict addressed

What to Do with Diverged Branches

Sometimes upstream changes take the codebase in a radically different direction…

… Additional sections with more data, examples, and insider advice …