forgejo-federation/docs/content/doc/advanced/migrations.en-us.md

---
date: "2019-04-15T17:29:00+08:00"
title: "Advanced: Migrations Interfaces"
slug: "migrations-interfaces"
weight: 30
toc: true
draft: false
menu:
  sidebar:
    parent: "advanced"
    name: "Migrations Interfaces"
    weight: 55
    identifier: "migrations-interfaces"
---

# Migration Features

The new migration features were introduced in Gitea 1.9.0. It defines two interfaces to support migrating
repositories data from other git host platforms to gitea or, in the future migrating gitea data to other
git host platforms. Currently, migrations from Github, Gitlab and Gitea to Gitea is implemented.

First of all, Gitea defines some standard objects in packages `modules/migrations/base`. They are
 `Repository`, `Milestone`, `Release`, `ReleaseAsset`, `Label`, `Issue`, `Comment`, `PullRequest`, `Reaction`, `Review`, `ReviewComment`.

## Downloader Interfaces

To migrate from a new git host platform, there are two steps to be updated.

- You should implement a `Downloader` which will get all kinds of repository informations.
- You should implement a `DownloaderFactory` which is used to detect if the URL matches and
create a Downloader.
- You'll need to register the `DownloaderFactory` via `RegisterDownloaderFactory` on init.

```Go
type Downloader interface {
	GetAsset(relTag string, relID, id int64) (io.ReadCloser, error)
	SetContext(context.Context)
	GetRepoInfo() (*Repository, error)
	GetTopics() ([]string, error)
	GetMilestones() ([]*Milestone, error)
	GetReleases() ([]*Release, error)
	GetLabels() ([]*Label, error)
	GetIssues(page, perPage int) ([]*Issue, bool, error)
	GetComments(issueNumber int64) ([]*Comment, error)
	GetPullRequests(page, perPage int) ([]*PullRequest, bool, error)
	GetReviews(pullRequestNumber int64) ([]*Review, error)
}
```

```Go
type DownloaderFactory interface {
	New(ctx context.Context, opts MigrateOptions) (Downloader, error)
	GitServiceType() structs.GitServiceType
}
```

## Uploader Interface

Currently, only a `GiteaLocalUploader` is implemented, so we only save downloaded
data via this `Uploader` on the local Gitea instance. Other uploaders are not supported
and will be implemented in future.

```Go
// Uploader uploads all the informations
type Uploader interface {
	MaxBatchInsertSize(tp string) int
	CreateRepo(repo *Repository, opts MigrateOptions) error
	CreateTopics(topic ...string) error
	CreateMilestones(milestones ...*Milestone) error
	CreateReleases(downloader Downloader, releases ...*Release) error
	SyncTags() error
	CreateLabels(labels ...*Label) error
	CreateIssues(issues ...*Issue) error
	CreateComments(comments ...*Comment) error
	CreatePullRequests(prs ...*PullRequest) error
	CreateReviews(reviews ...*Review) error
	Rollback() error
	Close()
}

```