# Switching to GitLab API v4

GitLab provides a new API version (v4) since its 9.0 release. `python-gitlab` provides support for this new version, but the python API has been modified to solve some problems with the existing one.

GitLab does not support the v3 API anymore, and you should consider switching to v4 if you use a recent version of GitLab (>= 9.0), or if you use https://gitlab.com.

## Using the v4 API

python-gitlab uses the v4 API by default since the 1.3.0 release. If you are migrating from an older release, make sure that you remove the `api_version` definition in you constructors and configuration file:

The following examples are not valid anymore:

    gl = gitlab.Gitlab(..., api_version=3)

    [my_gitlab]
    ...
    api_version = 3

## Changes between v3 and v4 API

For a list of GitLab (upstream) API changes, see https://docs.gitlab.com/ce/api/v3_to_v4.html.

The `python-gitlab` API reflects these changes. But also consider the following important changes in the python API:

- managers and objects don’t inherit from `GitlabObject` and `BaseManager` anymore. They inherit from `RESTManager` and `RESTObject`.

- You should only use the managers to perform CRUD operations.

  The following v3 code:

      gl = gitlab.Gitlab(...)
      p = Project(gl, project_id)

  Should be replaced with:

      gl = gitlab.Gitlab(...)
      p = gl.projects.get(project_id)

- Listing methods (`manager.list()` for instance) can now return generators (`RESTObjectList`). They handle the calls to the API when needed to fetch new items.

  By default you will still get lists. To get generators use `as_list=False`:

      all_projects_g = gl.projects.list(as_list=False)

- The “nested” managers (for instance `gl.project_issues` or `gl.group_members`) are not available anymore. Their goal was to provide a direct way to manage nested objects, and to limit the number of needed API calls.

  To limit the number of API calls, you can now use `get()` methods with the `lazy=True` parameter. This creates shallow objects that provide usual managers.

  The following v3 code:

      issues = gl.project_issues.list(project_id=project_id)

  Should be replaced with:

      issues = gl.projects.get(project_id, lazy=True).issues.list()

  This will make only one API call, instead of two if `lazy` is not used.

- The following `Gitlab` methods should not be used anymore for v4:

  - `list()`
  - `get()`
  - `create()`
  - `update()`
  - `delete()`

- If you need to perform HTTP requests to the GitLab server (which you shouldn’t), you can use the following `Gitlab` methods:

  - `http_request`
  - `http_get`
  - `http_list`
  - `http_post`
  - `http_put`
  - `http_delete`