5 files changed, 20 insertions, 14 deletions

diff --git a/server/controllers/api/videos/index.ts b/server/controllers/api/videos/index.ts
index c07430e6c..bcf1eaee6 100644
--- a/server/controllers/api/videos/index.ts
+++ b/server/controllers/api/videos/index.ts
@@ -244,7 +244,7 @@ async function addVideo (req: express.Request, res: express.Response, videoPhysi
 
     video.VideoFiles = [ videoFile ]
 
-    if (videoInfo.tags) {
+    if (videoInfo.tags !== undefined) {
       const tagInstances = await TagModel.findOrCreateTags(videoInfo.tags, t)
 
       await video.$set('Tags', tagInstances, sequelizeOptions)
@@ -332,7 +332,7 @@ async function updateVideo (req: express.Request, res: express.Response) {
       const videoInstanceUpdated = await videoInstance.save(sequelizeOptions)
 
       // Video tags update?
-      if (videoInfoToUpdate.tags) {
+      if (videoInfoToUpdate.tags !== undefined) {
         const tagInstances = await TagModel.findOrCreateTags(videoInfoToUpdate.tags, t)
 
         await videoInstanceUpdated.$set('Tags', tagInstances, sequelizeOptions)
diff --git a/server/helpers/custom-validators/misc.ts b/server/helpers/custom-validators/misc.ts
index 275482fa1..254b4db6c 100644
--- a/server/helpers/custom-validators/misc.ts
+++ b/server/helpers/custom-validators/misc.ts
@@ -35,7 +35,7 @@ function toIntOrNull (value: string) {
   return validator.toInt(value)
 }
 
-function toStringOrNull (value: string) {
+function toValueOrNull (value: string) {
   if (value === 'null') return null
 
   return value
@@ -73,7 +73,7 @@ export {
   isUUIDValid,
   isIdOrUUIDValid,
   isDateValid,
-  toStringOrNull,
+  toValueOrNull,
   isBooleanValid,
   toIntOrNull,
   isFileValid
diff --git a/server/helpers/custom-validators/videos.ts b/server/helpers/custom-validators/videos.ts
index c35db49ac..002324fe0 100644
--- a/server/helpers/custom-validators/videos.ts
+++ b/server/helpers/custom-validators/videos.ts
@@ -57,9 +57,11 @@ function isVideoTagValid (tag: string) {
 }
 
 function isVideoTagsValid (tags: string[]) {
-  return isArray(tags) &&
-         validator.isInt(tags.length.toString(), VIDEOS_CONSTRAINTS_FIELDS.TAGS) &&
-         tags.every(tag => isVideoTagValid(tag))
+  return tags === null || (
+    isArray(tags) &&
+    validator.isInt(tags.length.toString(), VIDEOS_CONSTRAINTS_FIELDS.TAGS) &&
+    tags.every(tag => isVideoTagValid(tag))
+  )
 }
 
 function isVideoAbuseReasonValid (value: string) {
diff --git a/server/middlewares/validators/videos.ts b/server/middlewares/validators/videos.ts
index aa2afb068..dd0246a63 100644
--- a/server/middlewares/validators/videos.ts
+++ b/server/middlewares/validators/videos.ts
@@ -2,7 +2,7 @@ import * as express from 'express'
 import 'express-validator'
 import { body, param, query } from 'express-validator/check'
 import { UserRight, VideoPrivacy } from '../../../shared'
-import { isBooleanValid, isIdOrUUIDValid, isIdValid, isUUIDValid, toIntOrNull, toStringOrNull } from '../../helpers/custom-validators/misc'
+import { isBooleanValid, isIdOrUUIDValid, isIdValid, isUUIDValid, toIntOrNull, toValueOrNull } from '../../helpers/custom-validators/misc'
 import {
   isVideoAbuseReasonValid,
   isVideoCategoryValid,
@@ -52,21 +52,22 @@ const videosAddValidator = [
     .custom(isVideoLicenceValid).withMessage('Should have a valid licence'),
   body('language')
     .optional()
-    .customSanitizer(toStringOrNull)
+    .customSanitizer(toValueOrNull)
     .custom(isVideoLanguageValid).withMessage('Should have a valid language'),
   body('nsfw')
     .toBoolean()
     .custom(isBooleanValid).withMessage('Should have a valid NSFW attribute'),
   body('description')
     .optional()
-    .customSanitizer(toStringOrNull)
+    .customSanitizer(toValueOrNull)
     .custom(isVideoDescriptionValid).withMessage('Should have a valid description'),
   body('support')
     .optional()
-    .customSanitizer(toStringOrNull)
+    .customSanitizer(toValueOrNull)
     .custom(isVideoSupportValid).withMessage('Should have a valid support text'),
   body('tags')
     .optional()
+    .customSanitizer(toValueOrNull)
     .custom(isVideoTagsValid).withMessage('Should have correct tags'),
   body('commentsEnabled')
     .toBoolean()
@@ -142,7 +143,7 @@ const videosUpdateValidator = [
     .custom(isVideoLicenceValid).withMessage('Should have a valid licence'),
   body('language')
     .optional()
-    .customSanitizer(toStringOrNull)
+    .customSanitizer(toValueOrNull)
     .custom(isVideoLanguageValid).withMessage('Should have a valid language'),
   body('nsfw')
     .optional()
@@ -154,14 +155,15 @@ const videosUpdateValidator = [
     .custom(isVideoPrivacyValid).withMessage('Should have correct video privacy'),
   body('description')
     .optional()
-    .customSanitizer(toStringOrNull)
+    .customSanitizer(toValueOrNull)
     .custom(isVideoDescriptionValid).withMessage('Should have a valid description'),
   body('support')
     .optional()
-    .customSanitizer(toStringOrNull)
+    .customSanitizer(toValueOrNull)
     .custom(isVideoSupportValid).withMessage('Should have a valid support text'),
   body('tags')
     .optional()
+    .customSanitizer(toValueOrNull)
     .custom(isVideoTagsValid).withMessage('Should have correct tags'),
   body('commentsEnabled')
     .optional()
diff --git a/server/models/video/tag.ts b/server/models/video/tag.ts
index 0ae74d808..6d79a5575 100644
--- a/server/models/video/tag.ts
+++ b/server/models/video/tag.ts
@@ -37,6 +37,8 @@ export class TagModel extends Model<TagModel> {
   Videos: VideoModel[]
 
   static findOrCreateTags (tags: string[], transaction: Transaction) {
+    if (tags === null) return []
+
     const tasks: Bluebird<TagModel>[] = []
     tags.forEach(tag => {
       const query = {