MM-27312 Allow uploading 10 files per post (#16235)

* Allow uploading 10 files per post

* Increase Post.Fileids column size to fit 10 files

* Add Post.Fileids column changes to DB v531

* Fix current_schema_version

Co-authored-by: Claudio Costa <cstcld91@gmail.com>

* Update store/sqlstore/upgrade.go

Co-authored-by: Claudio Costa <cstcld91@gmail.com>

* Fix schema version

Co-authored-by: Diogo Lima Nicolau <diogo.lima.nicolau@cern.ch>
Co-authored-by: Harrison Healey <harrisonmhealey@gmail.com>
Co-authored-by: Claudio Costa <cstcld91@gmail.com>
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/post.go

@@ -45,7 +45,8 @@ const (
 	POST_EPHEMERAL              = "system_ephemeral"
 	POST_CHANGE_CHANNEL_PRIVACY = "system_change_chan_privacy"
 	POST_ADD_BOT_TEAMS_CHANNELS = "add_bot_teams_channels"
-	POST_FILEIDS_MAX_RUNES      = 150
+	POST_MAX_FILES              = 10
+	POST_FILEIDS_MAX_RUNES      = 300
 	POST_FILENAMES_MAX_RUNES    = 4000
 	POST_HASHTAGS_MAX_RUNES     = 1000
 	POST_MESSAGE_MAX_RUNES_V1   = 4000
@@ -325,10 +326,14 @@ func (o *Post) IsValid(maxPostSize int) *AppError {
 		return NewAppError("Post.IsValid", "model.post.is_valid.filenames.app_error", nil, "id="+o.Id, http.StatusBadRequest)
 	}
 
-	if utf8.RuneCountInString(ArrayToJson(o.FileIds)) > POST_FILEIDS_MAX_RUNES {
+	if len(o.FileIds) > POST_MAX_FILES {
 		return NewAppError("Post.IsValid", "model.post.is_valid.file_ids.app_error", nil, "id="+o.Id, http.StatusBadRequest)
 	}
 
+	if utf8.RuneCountInString(ArrayToJson(o.FileIds)) > POST_FILEIDS_MAX_RUNES {
+		return NewAppError("Post.IsValid", "model.post.is_valid.file_ids.app_error", nil, "id="+o.Id, http.StatusInternalServerError)
+	}
+
 	if utf8.RuneCountInString(StringInterfaceToJson(o.GetProps())) > POST_PROPS_MAX_RUNES {
 		return NewAppError("Post.IsValid", "model.post.is_valid.props.app_error", nil, "id="+o.Id, http.StatusBadRequest)
 	}