# Merge Requests

Merge requests allow you to exchange changes you made to source code and
collaborate with other people on the same project.

## Authorization for merge requests

There are two main ways to have a merge request flow with GitLab:

1. Working with [protected branches][] in a single repository
1. Working with forks of an authoritative project

[Learn more about the authorization for merge requests.](merge_requests/authorization_for_merge_requests.md)

## Cherry-pick changes

Cherry-pick any commit in the UI by simply clicking the **Cherry-pick** button
in a merged merge requests or a commit.

[Learn more about cherry-picking changes.](merge_requests/cherry_pick_changes.md)

## Merge when pipeline succeeds

When reviewing a merge request that looks ready to merge but still has one or
more CI builds running, you can set it to be merged automatically when CI
pipeline succeeds. This way, you don't have to wait for the pipeline to finish
and remember to merge the request manually.

[Learn more about merging when pipeline succeeds.](merge_requests/merge_when_pipeline_succeeds.md)

## Resolve discussion comments in merge requests reviews

Keep track of the progress during a code review with resolving comments.
Resolving comments prevents you from forgetting to address feedback and lets
you hide discussions that are no longer relevant.

[Read more about resolving discussion comments in merge requests reviews.](merge_requests/merge_request_discussion_resolution.md)

## Resolve conflicts

When a merge request has conflicts, GitLab may provide the option to resolve
those conflicts in the GitLab UI.

[Learn more about resolving merge conflicts in the UI.](merge_requests/resolve_conflicts.md)

## Revert changes

GitLab implements Git's powerful feature to revert any commit with introducing
a **Revert** button in merge requests and commit details.

[Learn more about reverting changes in the UI](merge_requests/revert_changes.md)

## Merge requests versions

Every time you push to a branch that is tied to a merge request, a new version
of merge request diff is created. When you visit a merge request that contains
more than one pushes, you can select and compare the versions of those merge
request diffs.

[Read more about the merge requests versions.](merge_requests/versions.md)

## Work In Progress merge requests

To prevent merge requests from accidentally being accepted before they're
completely ready, GitLab blocks the "Accept" button for merge requests that
have been marked as a **Work In Progress**.

[Learn more about settings a merge request as "Work In Progress".](merge_requests/work_in_progress_merge_requests.md)

## Ignore whitespace changes in Merge Request diff view

If you click the **Hide whitespace changes** button, you can see the diff
without whitespace changes (if there are any). This is also working when on a
specific commit page.

![MR diff](merge_requests/img/merge_request_diff.png)

>**Tip:**
You can append `?w=1` while on the diffs page of a merge request to ignore any
whitespace changes.

## Tips

Here are some tips that will help you be more efficient with merge requests in
the command line.

> **Note:**
This section might move in its own document in the future.

### Checkout merge requests locally

A merge request contains all the history from a repository, plus the additional
commits added to the branch associated with the merge request. Here's a few
tricks to checkout a merge request locally.

Please note that you can checkout a merge request locally even if the source
project is a fork (even a private fork) of the target project.

#### Checkout locally by adding a git alias

Add the following alias to your `~/.gitconfig`:

```
[alias]
    mr = !sh -c 'git fetch $1 merge-requests/$2/head:mr-$1-$2 && git checkout mr-$1-$2' -
```

Now you can check out a particular merge request from any repository and any
remote. For example, to check out the merge request with ID 5 as shown in GitLab
from the `upstream` remote, do:

```
git mr upstream 5
```

This will fetch the merge request into a local `mr-upstream-5` branch and check
it out.

#### Checkout locally by modifying `.git/config` for a given repository

Locate the section for your GitLab remote in the `.git/config` file. It looks
like this:

```
[remote "origin"]
  url = https://gitlab.com/gitlab-org/gitlab-ce.git
  fetch = +refs/heads/*:refs/remotes/origin/*
```

You can open the file with:

```
git config -e
```

Now add the following line to the above section:

```
fetch = +refs/merge-requests/*/head:refs/remotes/origin/merge-requests/*
```

In the end, it should look like this:

```
[remote "origin"]
  url = https://gitlab.com/gitlab-org/gitlab-ce.git
  fetch = +refs/heads/*:refs/remotes/origin/*
  fetch = +refs/merge-requests/*/head:refs/remotes/origin/merge-requests/*
```

Now you can fetch all the merge requests:

```
git fetch origin

...
From https://gitlab.com/gitlab-org/gitlab-ce.git
 * [new ref]         refs/merge-requests/1/head -> origin/merge-requests/1
 * [new ref]         refs/merge-requests/2/head -> origin/merge-requests/2
...
```

And to check out a particular merge request:

```
git checkout origin/merge-requests/1
```

[protected branches]: protected_branches.md
