Remove stars when repo goes private (#19904)

Fixes #18600

2 files changed, 32 insertions, 0 deletions

diff --git a/models/repo/star.go b/models/repo/star.go
index b3d3d795f8..89bdb7ac05 100644
--- a/models/repo/star.go
+++ b/models/repo/star.go
@@ -85,3 +85,17 @@ func GetStargazers(repo *Repository, opts db.ListOptions) ([]*user_model.User, e
 	users := make([]*user_model.User, 0, 8)
 	return users, sess.Find(&users)
 }
+
+// ClearRepoStars clears all stars for a repository and from the user that starred it.
+// Used when a repository is set to private.
+func ClearRepoStars(ctx context.Context, repoID int64) error {
+	if _, err := db.Exec(ctx, "UPDATE `user` SET num_stars=num_stars-1 WHERE id IN (SELECT `uid` FROM `star` WHERE repo_id = ?)", repoID); err != nil {
+		return err
+	}
+
+	if _, err := db.Exec(ctx, "UPDATE `repository` SET num_stars = 0 WHERE id = ?", repoID); err != nil {
+		return err
+	}
+
+	return db.DeleteBeans(ctx, Star{RepoID: repoID})
+}
diff --git a/models/repo/star_test.go b/models/repo/star_test.go
index 7221a6c8eb..f15ac12ebe 100644
--- a/models/repo/star_test.go
+++ b/models/repo/star_test.go
@@ -51,3 +51,21 @@ func TestRepository_GetStargazers2(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Len(t, gazers, 0)
 }
+
+func TestClearRepoStars(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	const userID = 2
+	const repoID = 1
+	unittest.AssertNotExistsBean(t, &repo_model.Star{UID: userID, RepoID: repoID})
+	assert.NoError(t, repo_model.StarRepo(userID, repoID, true))
+	unittest.AssertExistsAndLoadBean(t, &repo_model.Star{UID: userID, RepoID: repoID})
+	assert.NoError(t, repo_model.StarRepo(userID, repoID, false))
+	unittest.AssertNotExistsBean(t, &repo_model.Star{UID: userID, RepoID: repoID})
+	assert.NoError(t, repo_model.ClearRepoStars(db.DefaultContext, repoID))
+	unittest.AssertNotExistsBean(t, &repo_model.Star{UID: userID, RepoID: repoID})
+
+	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 1})
+	gazers, err := repo_model.GetStargazers(repo, db.ListOptions{Page: 0})
+	assert.NoError(t, err)
+	assert.Len(t, gazers, 0)
+}