PLT-6217-bis Fixes system message posted to Town Square when a user joins a team #7863 (#7864)

* Adds new string post message when a user has joined a team (#6483)

* Simplifies long if statement in post.go (#6483)

app/channel.go

@@ -64,7 +64,7 @@ func (a *App) JoinDefaultChannels(teamId string, user *model.User, channelRole s
 		}
 
 		if requestor == nil {
-			if err := a.postJoinChannelMessage(user, townSquare); err != nil {
+			if err := a.postJoinTeamMessage(user, townSquare); err != nil {
 				l4g.Error(utils.T("api.channel.post_user_add_remove_message_and_forget.error"), err)
 			}
 		} else {
@@ -965,6 +965,24 @@ func (a *App) postJoinChannelMessage(user *model.User, channel *model.Channel) *
 	return nil
 }
 
+func (a *App) postJoinTeamMessage(user *model.User, channel *model.Channel) *model.AppError {
+	post := &model.Post{
+		ChannelId: channel.Id,
+		Message:   fmt.Sprintf(utils.T("api.team.join_team.post_and_forget"), user.Username),
+		Type:      model.POST_JOIN_TEAM,
+		UserId:    user.Id,
+		Props: model.StringInterface{
+			"username": user.Username,
+		},
+	}
+
+	if _, err := a.CreatePost(post, channel, false); err != nil {
+		return model.NewAppError("postJoinTeamMessage", "api.channel.post_user_add_remove_message_and_forget.error", nil, err.Error(), http.StatusInternalServerError)
+	}
+
+	return nil
+}
+
 func (a *App) LeaveChannel(channelId string, userId string) *model.AppError {
 	sc := a.Srv.Store.Channel().Get(channelId, true)
 	uc := a.Srv.Store.User().Get(userId)

i18n/en.json

@@ -2286,6 +2286,10 @@
     "id": "api.team.is_team_creation_allowed.domain.app_error",
     "translation": "Email must be from a specific domain (e.g. @example.com). Please ask your systems administrator for details."
   },
+  {
+    "id": "api.team.join_team.post_and_forget",
+    "translation": "%v joined the team."
+  },
   {
     "id": "api.team.leave.left",
     "translation": "%v left the team."

model/post.go

@@ -20,6 +20,7 @@ const (
 	POST_JOIN_LEAVE            = "system_join_leave" // Deprecated, use POST_JOIN_CHANNEL or POST_LEAVE_CHANNEL instead
 	POST_JOIN_CHANNEL          = "system_join_channel"
 	POST_LEAVE_CHANNEL         = "system_leave_channel"
+	POST_JOIN_TEAM             = "system_join_team"
 	POST_LEAVE_TEAM            = "system_leave_team"
 	POST_ADD_REMOVE            = "system_add_remove" // Deprecated, use POST_ADD_TO_CHANNEL or POST_REMOVE_FROM_CHANNEL instead
 	POST_ADD_TO_CHANNEL        = "system_add_to_channel"
@@ -169,13 +170,27 @@ func (o *Post) IsValid() *AppError {
 		return NewAppError("Post.IsValid", "model.post.is_valid.hashtags.app_error", nil, "id="+o.Id, http.StatusBadRequest)
 	}
 
-	if !(o.Type == POST_DEFAULT || o.Type == POST_JOIN_LEAVE || o.Type == POST_ADD_REMOVE ||
-		o.Type == POST_JOIN_CHANNEL || o.Type == POST_LEAVE_CHANNEL || o.Type == POST_LEAVE_TEAM ||
-		o.Type == POST_REMOVE_FROM_CHANNEL || o.Type == POST_ADD_TO_CHANNEL || o.Type == POST_ADD_TO_TEAM ||
-		o.Type == POST_SLACK_ATTACHMENT || o.Type == POST_HEADER_CHANGE || o.Type == POST_PURPOSE_CHANGE ||
-		o.Type == POST_DISPLAYNAME_CHANGE || o.Type == POST_CHANNEL_DELETED ||
-		strings.HasPrefix(o.Type, POST_CUSTOM_TYPE_PREFIX)) {
-		return NewAppError("Post.IsValid", "model.post.is_valid.type.app_error", nil, "id="+o.Type, http.StatusBadRequest)
+	switch o.Type {
+	case
+		POST_DEFAULT,
+		POST_JOIN_LEAVE,
+		POST_ADD_REMOVE,
+		POST_JOIN_CHANNEL,
+		POST_LEAVE_CHANNEL,
+		POST_LEAVE_TEAM,
+		POST_REMOVE_FROM_CHANNEL,
+		POST_ADD_TO_CHANNEL,
+		POST_ADD_TO_TEAM,
+		POST_JOIN_TEAM,
+		POST_SLACK_ATTACHMENT,
+		POST_HEADER_CHANGE,
+		POST_PURPOSE_CHANGE,
+		POST_DISPLAYNAME_CHANGE,
+		POST_CHANNEL_DELETED:
+	default:
+		if !strings.HasPrefix(o.Type, POST_CUSTOM_TYPE_PREFIX) {
+			return NewAppError("Post.IsValid", "model.post.is_valid.type.app_error", nil, "id="+o.Type, http.StatusBadRequest)
+		}
 	}
 
 	if utf8.RuneCountInString(ArrayToJson(o.Filenames)) > POST_FILENAMES_MAX_RUNES {