Fix emptying video tags

server/controllers/api/videos/index.ts

@@ -347,12 +347,13 @@ async function updateVideo (req: express.Request, res: express.Response) {
       if (previewModel) await videoInstanceUpdated.addAndSaveThumbnail(previewModel, t)
 
       // Video tags update?
-      await setVideoTags({
-        video: videoInstanceUpdated,
-        tags: videoInfoToUpdate.tags,
-        transaction: t,
-        defaultValue: videoInstanceUpdated.Tags
-      })
+      if (videoInfoToUpdate.tags !== undefined) {
+        await setVideoTags({
+          video: videoInstanceUpdated,
+          tags: videoInfoToUpdate.tags,
+          transaction: t
+        })
+      }
 
       // Video channel update?
       if (res.locals.videoChannel && videoInstanceUpdated.channelId !== res.locals.videoChannel.id) {

server/lib/activitypub/videos.ts

@@ -440,7 +440,7 @@ async function updateVideoFromAP (options: {
         const tags = videoObject.tag
                                 .filter(isAPHashTagObject)
                                 .map(tag => tag.name)
-        await setVideoTags({ video: videoUpdated, tags, transaction: t, defaultValue: videoUpdated.Tags })
+        await setVideoTags({ video: videoUpdated, tags, transaction: t })
       }
 
       // Update trackers

server/lib/video.ts

@@ -4,7 +4,7 @@ import { sequelizeTypescript } from '@server/initializers/database'
 import { TagModel } from '@server/models/video/tag'
 import { VideoModel } from '@server/models/video/video'
 import { FilteredModelAttributes } from '@server/types'
-import { MTag, MThumbnail, MUserId, MVideo, MVideoFile, MVideoTag, MVideoThumbnail, MVideoUUID } from '@server/types/models'
+import { MThumbnail, MUserId, MVideo, MVideoFile, MVideoTag, MVideoThumbnail, MVideoUUID } from '@server/types/models'
 import { ThumbnailType, VideoCreate, VideoPrivacy, VideoTranscodingPayload } from '@shared/models'
 import { federateVideoIfNeeded } from './activitypub/videos'
 import { JobQueue } from './job-queue/job-queue'
@@ -69,18 +69,14 @@ async function setVideoTags (options: {
   video: MVideoTag
   tags: string[]
   transaction?: Transaction
-  defaultValue?: MTag[]
 }) {
-  const { video, tags, transaction, defaultValue } = options
-  // Set tags to the video
-  if (tags) {
-    const tagInstances = await TagModel.findOrCreateTags(tags, transaction)
+  const { video, tags, transaction } = options
 
-    await video.$set('Tags', tagInstances, { transaction })
-    video.Tags = tagInstances
-  } else {
-    video.Tags = defaultValue || []
-  }
+  const internalTags = tags || []
+  const tagInstances = await TagModel.findOrCreateTags(internalTags, transaction)
+
+  await video.$set('Tags', tagInstances, { transaction })
+  video.Tags = tagInstances
 }
 
 async function publishAndFederateIfNeeded (video: MVideoUUID, wasLive = false) {