| `author_id` | integer | no | Returns merge requests created by the given user `id`. Mutually exclusive with `author_username`. _([Introduced](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/13060) in GitLab 9.5)_. |
| `author_username` | string | no | Returns merge requests created by the given `username`. Mutually exclusive with `author_id`. _([Introduced](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/13060) in GitLab 12.10)_. |
| `assignee_id` | integer | no | Returns merge requests assigned to the given user `id`. `None` returns unassigned merge requests. `Any` returns merge requests with an assignee. _([Introduced](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/13060) in GitLab 9.5)_. |
| `approver_ids`**(PREMIUM))** | integer array | no | Returns merge requests which have specified all the users with the given `id`s as individual approvers. `None` returns merge requests without approvers. `Any` returns merge requests with an approver. |
| `approver_ids`**(PREMIUM)** | integer array | no | Returns merge requests which have specified all the users with the given `id`s as individual approvers. `None` returns merge requests without approvers. `Any` returns merge requests with an approver. |
| `approved_by_ids`**(PREMIUM)** | integer array | no | Returns merge requests which have been approved by all the users with the given `id`s (Max: 5). `None` returns merge requests with no approvals. `Any` returns merge requests with an approval. |
| `reviewer_id` | integer | no | Returns merge requests which have the user as a [reviewer](../user/project/merge_requests/getting_started.md#reviewer) with the given user `id`. `None` returns merge requests with no reviewers. `Any` returns merge requests with any reviewer. Mutually exclusive with `reviewer_username`. |
| `reviewer_username` | string | no | Returns merge requests which have the user as a [reviewer](../user/project/merge_requests/getting_started.md#reviewer) with the given `username`. `None` returns merge requests with no reviewers. `Any` returns merge requests with any reviewer. Mutually exclusive with `reviewer_id`. |