Topic hooks extension (#8413)

* Update data.js with new hook

Implemented new 'filter:topic.getFields' hook as in posts

* Update data.js

* Update data.js

src/topics/data.js

@@ -6,6 +6,7 @@ var db = require('../database');
 var categories = require('../categories');
 var utils = require('../utils');
 var translator = require('../translator');
+const plugins = require('../plugins');
 
 const intFields = [
 	'tid', 'cid', 'uid', 'mainPid', 'postcount',
@@ -21,8 +22,14 @@ module.exports = function (Topics) {
 		}
 		const keys = tids.map(tid => 'topic:' + tid);
 		const topics = await (fields.length ? db.getObjectsFields(keys, fields) : db.getObjects(keys));
-		topics.forEach(topic => modifyTopic(topic, fields));
-		return topics;
+		const result = await plugins.fireHook('filter:topic.getFields', {
+			tids: tids,
+			topics: topics,
+			fields: fields,
+			keys: keys,
+		});
+		result.topics.forEach(topic => modifyTopic(topic, fields));
+		return result.topics;
 	};
 
 	Topics.getTopicField = async function (tid, field) {