# GraphQL API

> - [Introduced][ce-19008] in GitLab 11.0 (enabled by feature flag `graphql`).
> - [Always enabled](https://gitlab.com/gitlab-org/gitlab-foss/merge_requests/30444)
  in GitLab 12.1.

[GraphQL](https://graphql.org/) is a query language for APIs that
allows clients to request exactly the data they need, making it
possible to get all required data in a limited number of requests.

The GraphQL data (fields) can be described in the form of types,
allowing clients to use [clientside GraphQL
libraries](https://graphql.org/code/#graphql-clients) to consume the
API and avoid manual parsing.

Since there's no fixed endpoints and datamodel, new abilities can be
added to the API without creating breaking changes. This allows us to
have a versionless API as described in [the GraphQL
documentation](https://graphql.org/learn/best-practices/#versioning).

## Vision

We want the GraphQL API to be the **primary** means of interacting
programmatically with GitLab. To achieve this, it needs full coverage - anything
possible in the REST API should also be possible in the GraphQL API.

To help us meet this vision, the frontend should use GraphQL in preference to
the REST API for new features.

There are no plans to deprecate the REST API. To reduce the technical burden of
supporting two APIs in parallel, they should share implementations as much as
possible.

## Available queries

A first iteration of a GraphQL API includes the following queries

1. `project` : Within a project it is also possible to fetch a `mergeRequest` by IID.
1. `group` : Basic group information and epics **(ULTIMATE)** are currently supported.
1. `namespace` : Within a namespace it is also possible to fetch `projects`.

### Multiplex queries

GitLab supports batching queries into a single request using
[apollo-link-batch-http](https://www.apollographql.com/docs/link/links/batch-http). More
info about multiplexed queries is also available for
[graphql-ruby](https://graphql-ruby.org/queries/multiplex.html) the
library GitLab uses on the backend.

## Reference

GitLab's GraphQL reference [is available](reference/index.md).

It is automatically generated from GitLab's GraphQL schema and embedded in a Markdown file.

## GraphiQL

The API can be explored by using the GraphiQL IDE, it is available on your
instance on `gitlab.example.com/-/graphql-explorer`.

[ce-19008]: https://gitlab.com/gitlab-org/gitlab-foss/merge_requests/19008
[features-api]: ../features.md
