fix blank topic (#3948)

public/js/index.js

@@ -2197,7 +2197,11 @@ function initTopicbar() {
                 alert(res.message);
             } else {
                 viewDiv.children(".topic").remove();
+                if (topics.length == 0) {
+                    return
+                }
                 var topicArray = topics.split(",");
+                
                 var last = viewDiv.children("a").last();
                 for (var i=0;i < topicArray.length; i++) {
                     $('<div class="ui green basic label topic" style="cursor:pointer;">'+topicArray[i]+'</div>').insertBefore(last)

routers/repo/topic.go

@@ -21,7 +21,11 @@ func TopicPost(ctx *context.Context) {
 		return
 	}
 
-	topics := strings.Split(ctx.Query("topics"), ",")
+	var topics = make([]string, 0)
+	var topicsStr = strings.TrimSpace(ctx.Query("topics"))
+	if len(topicsStr) > 0 {
+		topics = strings.Split(topicsStr, ",")
+	}
 
 	err := models.SaveTopics(ctx.Repo.Repository.ID, topics...)
 	if err != nil {