diff --git a/command.py b/command.py
index d9e0e67..4861d05 100644
--- a/command.py
+++ b/command.py
@@ -10,6 +10,7 @@ import util
 import variables as var
 from librb import radiobrowser
 from database import SettingsDatabase, MusicDatabase
+from media.item import item_builders, item_loaders, item_id_generators, dict_to_item, dicts_to_items
 from media.playlist import get_item_wrapper, get_item_wrapper_by_id, get_item_wrappers_by_tags
 from media.file import FileItem
 from media.url_from_playlist import PlaylistURLItem, get_playlist_info
@@ -58,6 +59,8 @@ def register_all_commands(bot):
     bot.register_command(constants.commands('add_tag'), cmd_add_tag)
     bot.register_command(constants.commands('remove_tag'), cmd_remove_tag)
     bot.register_command(constants.commands('find_tagged'), cmd_find_tagged)
+    bot.register_command(constants.commands('search'), cmd_search_library)
+    bot.register_command(constants.commands('add_from_shortlist'), cmd_shortlist)
     bot.register_command(constants.commands('drop_database'), cmd_drop_database, True)
     bot.register_command(constants.commands('rescan'), cmd_refresh_cache, True)
 
@@ -81,6 +84,10 @@ def send_multi_lines(bot, lines, text, linebreak="<br />"):
 
     bot.send_msg(msg, text)
 
+# ---------------- Variables -----------------
+
+song_shortlist = []
+
 # ---------------- Commands ------------------
 
 
@@ -169,13 +176,13 @@ def cmd_pause(bot, user, text, command, parameter):
 
 
 def cmd_play_file(bot, user, text, command, parameter, do_not_refresh_cache=False):
-    global log
+    global log, song_shortlist
 
     # if parameter is {index}
     if parameter.isdigit():
-        files = var.library.files
+        files = var.cache.files
         if int(parameter) < len(files):
-            music_wrapper = get_item_wrapper_by_id(bot, var.library.file_id_lookup[files[int(parameter)]], user)
+            music_wrapper = get_item_wrapper_by_id(bot, var.cache.file_id_lookup[files[int(parameter)]], user)
             var.playlist.append(music_wrapper)
             log.info("cmd: add to playlist: " + music_wrapper.format_debug_string())
             bot.send_msg(constants.strings('file_added', item=music_wrapper.format_song_string()), text)
@@ -189,7 +196,7 @@ def cmd_play_file(bot, user, text, command, parameter, do_not_refresh_cache=Fals
         #     bot.send_msg(constants.strings('no_file'), text)
         #     return
 
-        if parameter in var.library.files:
+        if parameter in var.cache.files:
             music_wrapper = get_item_wrapper(bot, type='file', path=parameter, user=user)
             var.playlist.append(music_wrapper)
             log.info("cmd: add to playlist: " + music_wrapper.format_debug_string())
@@ -197,14 +204,14 @@ def cmd_play_file(bot, user, text, command, parameter, do_not_refresh_cache=Fals
             return
 
         # if parameter is {folder}
-        files = var.library.dir.get_files(parameter)
+        files = var.cache.dir.get_files(parameter)
         if files:
             msgs = [constants.strings('multiple_file_added')]
             count = 0
 
             for file in files:
                 count += 1
-                music_wrapper = get_item_wrapper_by_id(bot, var.library.file_id_lookup[file],user)
+                music_wrapper = get_item_wrapper_by_id(bot, var.cache.file_id_lookup[file], user)
                 var.playlist.append(music_wrapper)
                 log.info("cmd: add to playlist: " + music_wrapper.format_debug_string())
                 msgs.append("{} ({})".format(music_wrapper.item().title, music_wrapper.item().path))
@@ -215,28 +222,34 @@ def cmd_play_file(bot, user, text, command, parameter, do_not_refresh_cache=Fals
 
         else:
             # try to do a partial match
-            files = var.library.files
-            matches = [(index, file) for index, file in enumerate(files) if parameter.lower() in file.lower()]
+            files = var.cache.files
+            matches = [ file for file in files if parameter.lower() in file.lower()]
             if len(matches) == 1:
-                file = matches[0][1]
-                music_wrapper = get_item_wrapper_by_id(bot, var.library.file_id_lookup[file],user)
+                file = matches[0]
+                music_wrapper = get_item_wrapper_by_id(bot, var.cache.file_id_lookup[file], user)
                 var.playlist.append(music_wrapper)
                 log.info("cmd: add to playlist: " + music_wrapper.format_debug_string())
                 bot.send_msg(constants.strings('file_added', item=music_wrapper.format_song_string()), text)
                 return
             elif len(matches) > 1:
                 msgs = [ constants.strings('multiple_matches') ]
-                for match in matches:
-                    music_wrapper = get_item_wrapper_by_id(bot, var.library.file_id_lookup[match[1]], user)
-                    msgs.append("<b>{:0>3d}</b> - <b>{:s}</b> ({:s})".format(
-                        match[0], music_wrapper.item().title, match[1]))
+                song_shortlist = []
+                for index, match in enumerate(matches):
+                    id = var.cache.file_id_lookup[match]
+                    music_dict = var.music_db.query_music_by_id(id)
+                    item = dict_to_item(bot, music_dict)
+
+                    song_shortlist.append(music_dict)
+
+                    msgs.append("<b>{:d}</b> - <b>{:s}</b> ({:s})".format(
+                        index + 1, item.title, match))
                 send_multi_lines(bot, msgs, text)
                 return
 
     if do_not_refresh_cache:
         bot.send_msg(constants.strings("no_file"), text)
     else:
-        var.library.build_dir_cache(bot)
+        var.cache.build_dir_cache(bot)
         cmd_play_file(bot, user, text, command, parameter, do_not_refresh_cache=True)
 
 
@@ -245,7 +258,7 @@ def cmd_play_file_match(bot, user, text, command, parameter, do_not_refresh_cach
 
     music_folder = var.music_folder
     if parameter:
-        files = var.library.files
+        files = var.cache.files
         msgs = [ constants.strings('multiple_file_added') + "<ul>"]
         count = 0
         try:
@@ -254,7 +267,7 @@ def cmd_play_file_match(bot, user, text, command, parameter, do_not_refresh_cach
                 match = re.search(parameter, file)
                 if match and match[0]:
                     count += 1
-                    music_wrapper = get_item_wrapper_by_id(bot, var.library.file_id_lookup[file], user)
+                    music_wrapper = get_item_wrapper_by_id(bot, var.cache.file_id_lookup[file], user)
                     music_wrappers.append(music_wrapper)
                     log.info("cmd: add to playlist: " + music_wrapper.format_debug_string())
                     msgs.append("<li><b>{}</b> ({})</li>".format(music_wrapper.item().title,
@@ -273,7 +286,7 @@ def cmd_play_file_match(bot, user, text, command, parameter, do_not_refresh_cach
                 if do_not_refresh_cache:
                     bot.send_msg(constants.strings("no_file"), text)
                 else:
-                    var.library.build_dir_cache(bot)
+                    var.cache.build_dir_cache(bot)
                     cmd_play_file_match(bot, user, text, command, parameter, do_not_refresh_cache=True)
 
         except re.error as e:
@@ -435,7 +448,7 @@ def cmd_rb_play(bot, user, text, command, parameter):
         url = radiobrowser.geturl_byid(parameter)
         if url != "-1":
             log.info('cmd: Found url: ' + url)
-            music_wrapper = get_item_wrapper(bot, type='radio', url=url, name=stationname)
+            music_wrapper = get_item_wrapper(bot, type='radio', url=url, name=stationname, user=user)
             var.playlist.append(music_wrapper)
             log.info("cmd: add to playlist: " + music_wrapper.format_debug_string())
             bot.async_download_next()
@@ -448,7 +461,7 @@ yt_last_result = []
 yt_last_page = 0 # TODO: if we keep adding global variables, we need to consider sealing all commands up into classes.
 
 def cmd_yt_search(bot, user, text, command, parameter):
-    global log, yt_last_result, yt_last_page
+    global log, yt_last_result, yt_last_page, song_shortlist
     item_per_page = 5
 
     if parameter:
@@ -456,6 +469,10 @@ def cmd_yt_search(bot, user, text, command, parameter):
         if parameter.startswith("-n"):
             yt_last_page += 1
             if len(yt_last_result) > yt_last_page * item_per_page:
+                song_shortlist = [{'type': 'url',
+                                   'url': "https://www.youtube.com/watch?v=" + result[0],
+                                   'title': result[1]
+                                   } for result in yt_last_result[yt_last_page * item_per_page: item_per_page]]
                 msg = _yt_format_result(yt_last_result, yt_last_page * item_per_page, item_per_page)
                 bot.send_msg(constants.strings('yt_result', result_table=msg), text)
             else:
@@ -467,6 +484,8 @@ def cmd_yt_search(bot, user, text, command, parameter):
             if results:
                 yt_last_result = results
                 yt_last_page = 0
+                song_shortlist = [{'type': 'url', 'url': "https://www.youtube.com/watch?v=" + result[0]}
+                                  for result in results[0: item_per_page]]
                 msg = _yt_format_result(results, 0, item_per_page)
                 bot.send_msg(constants.strings('yt_result', result_table=msg), text)
             else:
@@ -478,7 +497,7 @@ def _yt_format_result(results, start, count):
     msg = '<table><tr><th width="10%">Index</th><th>Title</th><th width="20%">Uploader</th></tr>'
     for index, item in enumerate(results[start:start+count]):
         msg += '<tr><td>{index:d}</td><td>{title}</td><td>{uploader}</td></tr>'.format(
-            index=index + 1 + start, title=item[1], uploader=item[2])
+            index=index + 1, title=item[1], uploader=item[2])
     msg += '</table>'
 
     return msg
@@ -488,18 +507,14 @@ def cmd_yt_play(bot, user, text, command, parameter):
     global log, yt_last_result, yt_last_page
 
     if parameter:
-        if parameter.isdigit() and 0 <= int(parameter) - 1 < len(yt_last_result):
-            url = "https://www.youtube.com/watch?v=" + yt_last_result[int(parameter) - 1][0]
+        results = util.youtube_search(parameter)
+        if results:
+            yt_last_result = results
+            yt_last_page = 0
+            url = "https://www.youtube.com/watch?v=" + yt_last_result[0][0]
             cmd_play_url(bot, user, text, command, url)
         else:
-            results = util.youtube_search(parameter)
-            if results:
-                yt_last_result = results
-                yt_last_page = 0
-                url = "https://www.youtube.com/watch?v=" + yt_last_result[0][0]
-                cmd_play_url(bot, user, text, command, url)
-            else:
-                bot.send_msg(constants.strings('yt_query_error'))
+            bot.send_msg(constants.strings('yt_query_error'))
     else:
         bot.send_msg(constants.strings('bad_parameter', command=command), text)
 
@@ -690,7 +705,7 @@ def cmd_remove(bot, user, text, command, parameter):
 def cmd_list_file(bot, user, text, command, parameter):
     global log
 
-    files = var.library.files
+    files = var.cache.files
     msgs = [ "<br> <b>Files available:</b>" if not parameter else "<br> <b>Matched files:</b>" ]
     try:
         count = 0
@@ -871,6 +886,8 @@ def cmd_remove_tag(bot, user, text, command, parameter):
     bot.send_msg(constants.strings('bad_parameter', command=command), text)
 
 def cmd_find_tagged(bot, user, text, command, parameter):
+    global song_shortlist
+
     if not parameter:
         bot.send_msg(constants.strings('bad_parameter', command=command))
         return
@@ -880,17 +897,99 @@ def cmd_find_tagged(bot, user, text, command, parameter):
 
     tags = parameter.split(",")
     tags = list(map(lambda t: t.strip(), tags))
-    music_wrappers = get_item_wrappers_by_tags(bot, tags, user)
-    for music_wrapper in music_wrappers:
+
+    music_dicts = var.music_db.query_music_by_tags(tags)
+    song_shortlist = music_dicts
+    items = dicts_to_items(bot, music_dicts)
+
+    for i, item in enumerate(items):
         count += 1
-        msgs.append("<li><b>{}</b> (<i>{}</i>)</li>".format(music_wrapper.item().title, ", ".join(music_wrapper.item().tags)))
+        msgs.append("<li><b>{:d}</b> - <b>{}</b> (<i>{}</i>)</li>".format(i+1, item.title, ", ".join(item.tags)))
 
     if count != 0:
         msgs.append("</ul>")
+        msgs.append(constants.strings("shortlist_instruction"))
         send_multi_lines(bot, msgs, text, "")
     else:
         bot.send_msg(constants.strings("no_file"), text)
 
+def cmd_search_library(bot, user, text, command, parameter):
+    global song_shortlist
+    if not parameter:
+        bot.send_msg(constants.strings('bad_parameter', command=command))
+        return
+
+    msgs = [constants.strings('multiple_file_found') + "<ul>"]
+    count = 0
+
+    _keywords = parameter.split(" ")
+    keywords = []
+    for kw in _keywords:
+        if kw:
+            keywords.append(kw)
+
+    music_dicts = var.music_db.query_music_by_keywords(keywords)
+    items = dicts_to_items(bot, music_dicts)
+    song_shortlist = music_dicts
+
+    for item in items:
+        count += 1
+        if len(item.tags) > 0:
+            msgs.append("<li><b>{:d}</b> - [{}] <b>{}</b> (<i>{}</i>)</li>".format(count, item.display_type(), item.title, ", ".join(item.tags)))
+        else:
+            msgs.append("<li><b>{:d}</b> - [{}] <b>{}</b> </li>".format(count, item.display_type(), item.title, ", ".join(item.tags)))
+
+    if count != 0:
+        msgs.append("</ul>")
+        msgs.append(constants.strings("shortlist_instruction"))
+        send_multi_lines(bot, msgs, text, "")
+    else:
+        bot.send_msg(constants.strings("no_file"), text)
+
+
+def cmd_shortlist(bot, user, text, command, parameter):
+    global song_shortlist
+    indexes = []
+    try:
+        indexes = [ int(i) for i in parameter.split(" ") ]
+    except ValueError:
+        bot.send_msg(constants.strings('bad_parameter', command=command), text)
+        return
+
+    if len(indexes) > 1:
+        msgs = [constants.strings('multiple_file_added') + "<ul>"]
+        for index in indexes:
+            if 1 <= index <= len(song_shortlist):
+                kwargs = song_shortlist[index - 1]
+                kwargs['user'] = user
+                music_wrapper = get_item_wrapper(bot, **kwargs)
+                var.playlist.append(music_wrapper)
+                log.info("cmd: add to playlist: " + music_wrapper.format_debug_string())
+                msgs.append("<li><b>{}</b></li>".format(music_wrapper.item().title))
+                song_shortlist = []
+            else:
+                bot.send_msg(constants.strings('bad_parameter', command=command), text)
+                return
+
+            msgs.append("</ul>")
+            send_multi_lines(bot, msgs, text, "")
+            song_shortlist = []
+            return
+    elif len(indexes) == 1:
+        index = indexes[0]
+        if 1 <= index <= len(song_shortlist):
+            kwargs = song_shortlist[index - 1]
+            kwargs['user'] = user
+            music_wrapper = get_item_wrapper(bot, **kwargs)
+            var.playlist.append(music_wrapper)
+            log.info("cmd: add to playlist: " + music_wrapper.format_debug_string())
+            bot.send_msg(constants.strings('file_added', item=music_wrapper.format_song_string()), text)
+            song_shortlist = []
+            return
+
+    bot.send_msg(constants.strings('bad_parameter', command=command), text)
+
+
 def cmd_drop_database(bot, user, text, command, parameter):
     global log
 
@@ -907,7 +1006,7 @@ def cmd_drop_database(bot, user, text, command, parameter):
 def cmd_refresh_cache(bot, user, text, command, parameter):
     global log
     if bot.is_admin(user):
-        var.library.build_dir_cache(bot)
+        var.cache.build_dir_cache(bot)
         log.info("command: Local file cache refreshed.")
         bot.send_msg(constants.strings('cache_refreshed'), text)
     else:
diff --git a/configuration.default.ini b/configuration.default.ini
index 598945b..3697784 100644
--- a/configuration.default.ini
+++ b/configuration.default.ini
@@ -160,6 +160,8 @@ play_tag = tag
 add_tag = addtag
 remove_tag = untag
 find_tagged = findtagged, ft
+search = search
+add_from_shortlist = shortlist, sl
 
 user_ban = userban
 user_unban = userunban
@@ -225,7 +227,7 @@ unknown_mode = Unknown playback mode '{mode}'. It should be one of <i>one-shot</
 current_mode = Current playback mode is <i>{mode}</i>.
 change_mode = Playback mode set to <i>{mode}</i> by {user}.
 repeat = Repeat {song} for {n} times.
-yt_result = Youtube query result: {result_table} Use <i>!ytplay</i> {{index}} to play the item you want. <br />
+yt_result = Youtube query result: {result_table} Use <i>!sl {{indexes}}</i> to play the item you want. <br />
             <i>!ytquery -n</i> for the next page.
 yt_no_more = No more results!
 yt_query_error = Unable to query youtube!
@@ -237,6 +239,7 @@ removed_tags = Removed tags <i>{tags}</i> from <b>{song}</b>.
 removed_tags_from_all = Removed tags <i>{tags}</i> from songs on the playlist.
 cleared_tags = Removed all tags from <b>{song}</b>.
 cleared_tags_from_all = Removed all tags from songs on the playlist.
+shortlist_instruction = Use <i>!sl {indexes}</i> to play the item you want.
 
 help = <h3>Commands</h3>
        <b>Control</b>
@@ -264,6 +267,7 @@ help = <h3>Commands</h3>
        <li> <b>!<u>ur</u>l </b> {url} - add Youtube or SoundCloud music </li>
        <li> <b>!<u>playl</u>ist </b> {url} [{offset}] - add all items in a Youtube or SoundCloud playlist, and start with the {offset}-th item </li>
        <li> <b>!<u>t</u>ag </b> {tags} - add all items with tags {tags}, tags separated by ",". </li>
+       <li> <b>!<u>sh</u>ortlist </b> (or <b>!sl</b>) {indexes} - add {indexes}-th item on the shortlist. </li>
        <li> <b>!rm </b> {num} - remove the num-th song on the playlist </li>
        <li> <b>!<u>rep</u>eat </b> [{num}] - repeat current song {num} (1 by default) times.</li>
        <li> <b>!<u>ran</u>dom </b> - randomize the playlist.</li>
@@ -275,8 +279,9 @@ help = <h3>Commands</h3>
        <li> <b>!<u>yp</u>lay </b> {index/keywords} - play an item from the list returned by <i>!ytquery</i>, or add the
        first search result of {keywords} into the playlist.</li>
        </ul>
-       <b>Tag</b>
+       <b>Music Library</b>
        <ul>
+       <li> <b>!<u>se</u>arch </b> {keywords} - find item with {keywords} in the music library, keywords separated by space.</li>
        <li> <b>!<u>addt</u>ag </b> {index} {tags} - add {tags} to {index}-th item on the playlist, tags separated by ",". </li>
        <li> <b>!<u>addt</u>ag </b> * {tags} - add {tags} to all items on the playlist. </li>
        <li> <b>!<u>un</u>tag </b> {index/*} {tags} - remove {tags} from {index}-th item on the playlist. </li>
diff --git a/database.py b/database.py
index 757c805..0540834 100644
--- a/database.py
+++ b/database.py
@@ -231,6 +231,40 @@ class MusicDatabase:
         else:
             return None
 
+    def query_music_by_keywords(self, keywords):
+        condition = []
+        filler = []
+
+        for keyword in keywords:
+            condition.append('title LIKE ?')
+            filler.append("%{:s}%".format(keyword))
+
+
+        condition_str = " AND ".join(condition)
+
+        conn = sqlite3.connect(self.db_path)
+        cursor = conn.cursor()
+        results = cursor.execute("SELECT id, type, title, metadata, tags FROM music "
+                                 "WHERE %s" % condition_str, filler).fetchall()
+        conn.close()
+
+        if len(results) > 0:
+            music_dicts = []
+            for result in results:
+                music_dict = json.loads(result[3])
+                music_dict['type'] = result[1]
+                music_dict['title'] = result[2]
+                music_dict['id'] = result[0]
+                music_dict['tags'] = result[4].strip(",").split(",")
+                if not music_dict['tags'][0]:
+                    music_dict['tags'] = []
+
+                music_dicts.append(music_dict)
+
+            return music_dicts
+        else:
+            return None
+
     def query_music_by_tags(self, tags):
         condition = []
         filler = []
diff --git a/interface.py b/interface.py
index a8607b9..15ae1ca 100644
--- a/interface.py
+++ b/interface.py
@@ -119,7 +119,7 @@ def build_tags_color_lookup():
 
 def build_path_tags_lookup():
     path_lookup = {}
-    items = var.library.file_id_lookup.items()
+    items = var.cache.file_id_lookup.items()
     for path, id in items:
         path_lookup[path] = var.music_db.query_tags_by_id(id)
 
@@ -133,17 +133,17 @@ def recur_dir(dirobj):
 @web.route("/", methods=['GET'])
 @requires_auth
 def index():
-    while var.library.dir_lock.locked():
+    while var.cache.dir_lock.locked():
         time.sleep(0.1)
 
     tags_color_lookup = build_tags_color_lookup()
     path_tags_lookup = build_path_tags_lookup()
 
     return render_template('index.html',
-                           all_files=var.library.files,
+                           all_files=var.cache.files,
                            tags_lookup=path_tags_lookup,
                            tags_color_lookup=tags_color_lookup,
-                           music_library=var.library.dir,
+                           music_library=var.cache.dir,
                            os=os,
                            playlist=var.playlist,
                            user=var.user,
@@ -198,7 +198,7 @@ def post():
         if 'add_file_bottom' in request.form and ".." not in request.form['add_file_bottom']:
             path = var.music_folder + request.form['add_file_bottom']
             if os.path.isfile(path):
-                music_wrapper = get_item_wrapper_by_id(var.bot, var.library.file_id_lookup[request.form['add_file_bottom']], user)
+                music_wrapper = get_item_wrapper_by_id(var.bot, var.cache.file_id_lookup[request.form['add_file_bottom']], user)
 
                 var.playlist.append(music_wrapper)
                 log.info('web: add to playlist(bottom): ' + music_wrapper.format_debug_string())
@@ -206,7 +206,7 @@ def post():
         elif 'add_file_next' in request.form and ".." not in request.form['add_file_next']:
             path = var.music_folder + request.form['add_file_next']
             if os.path.isfile(path):
-                music_wrapper = get_item_wrapper_by_id(var.bot, var.library.file_id_lookup[request.form['add_file_next']], user)
+                music_wrapper = get_item_wrapper_by_id(var.bot, var.cache.file_id_lookup[request.form['add_file_next']], user)
                 var.playlist.insert(var.playlist.current_index + 1, music_wrapper)
                 log.info('web: add to playlist(next): ' + music_wrapper.format_debug_string())
 
@@ -220,7 +220,7 @@ def post():
                 folder += '/'
 
             if os.path.isdir(var.music_folder + folder):
-                dir = var.library.dir
+                dir = var.cache.dir
                 if 'add_folder_recursively' in request.form:
                     files = dir.get_files_recursively(folder)
                 else:
@@ -228,7 +228,7 @@ def post():
 
                 music_wrappers = list(map(
                     lambda file:
-                    get_item_wrapper_by_id(var.bot, var.library.file_id_lookup[folder + file], user),
+                    get_item_wrapper_by_id(var.bot, var.cache.file_id_lookup[folder + file], user),
                 files))
 
                 var.playlist.extend(music_wrappers)
@@ -328,7 +328,7 @@ def post():
                 var.db.set('playlist', 'playback_mode', "autoplay")
                 log.info("web: playback mode changed to autoplay.")
             if action == "rescan":
-                var.library.build_dir_cache(var.bot)
+                var.cache.build_dir_cache(var.bot)
                 log.info("web: Local file cache refreshed.")
             elif action == "stop":
                 var.bot.stop()
@@ -413,7 +413,7 @@ def download():
         log.info('web: Download of file %s requested from %s:' % (requested_file, request.remote_addr))
         if '../' not in requested_file:
             folder_path = var.music_folder
-            files = var.library.files
+            files = var.cache.files
 
             if requested_file in files:
                 filepath = os.path.join(folder_path, requested_file)
diff --git a/media/library.py b/media/cache.py
similarity index 93%
rename from media/library.py
rename to media/cache.py
index 4eb7fcb..956293a 100644
--- a/media/library.py
+++ b/media/cache.py
@@ -3,13 +3,13 @@ from database import MusicDatabase
 import json
 import threading
 
-from media.item import item_builders, item_loaders, item_id_generators
+from media.item import item_builders, item_loaders, item_id_generators, dict_to_item, dicts_to_items
 from database import MusicDatabase
 import variables as var
 import util
 
 
-class MusicLibrary(dict):
+class MusicCache(dict):
     def __init__(self, db: MusicDatabase):
         super().__init__()
         self.db = db
@@ -36,7 +36,11 @@ class MusicLibrary(dict):
     def get_item(self, bot, **kwargs):
         # kwargs should provide type and id, and parameters to build the item if not existed in the library.
         # if cached
-        id = item_id_generators[kwargs['type']](**kwargs)
+        if 'id' in kwargs:
+            id = kwargs['id']
+        else:
+            id = item_id_generators[kwargs['type']](**kwargs)
+
         if id in self:
             return self[id]
 
@@ -57,8 +61,7 @@ class MusicLibrary(dict):
         if music_dicts:
             for music_dict in music_dicts:
                 id = music_dict['id']
-                type = music_dict['type']
-                self[id] = item_loaders[type](bot, music_dict)
+                self[id] = dict_to_item(bot, music_dict)
                 items.append(self[id])
 
         return items
@@ -67,8 +70,7 @@ class MusicLibrary(dict):
         music_dicts = self.db.query_music(id=id)
         if music_dicts:
             music_dict = music_dicts[0]
-            type = music_dict['type']
-            self[id] = item_loaders[type](bot, music_dict)
+            self[id] = dict_to_item(bot, music_dict)
             return self[id]
         else:
             return None
diff --git a/media/file.py b/media/file.py
index 980256e..38014d6 100644
--- a/media/file.py
+++ b/media/file.py
@@ -154,7 +154,7 @@ class FileItem(BaseItem):
     def format_song_string(self, user):
         return constants.strings("file_item",
                                     title=self.title,
-                                    artist=self.artist,
+                                    artist=self.artist if self.artist else '??',
                                     user=user
                                     )
 
diff --git a/media/item.py b/media/item.py
index 2ca6b7f..3eb8182 100644
--- a/media/item.py
+++ b/media/item.py
@@ -28,6 +28,18 @@ item_builders['base'] = example_builder
 item_loaders['base'] = example_loader
 item_id_generators['base'] = example_id_generator
 
+def dicts_to_items(bot, music_dicts):
+    items = []
+    for music_dict in music_dicts:
+        type = music_dict['type']
+        items.append(item_loaders[type](bot, music_dict))
+    return items
+
+def dict_to_item(bot, music_dict):
+    type = music_dict['type']
+    return item_loaders[type](bot, music_dict)
+
+
 class BaseItem:
     def __init__(self, bot, from_dict=None):
         self.bot = bot
diff --git a/media/playlist.py b/media/playlist.py
index dc489fe..aa79307 100644
--- a/media/playlist.py
+++ b/media/playlist.py
@@ -10,7 +10,7 @@ from media.url import URLItem
 from media.url_from_playlist import PlaylistURLItem
 from media.radio import RadioItem
 from database import MusicDatabase
-from media.library import MusicLibrary
+from media.cache import MusicCache
 
 class PlaylistItemWrapper:
     def __init__(self, lib, id, type, user):
@@ -95,24 +95,25 @@ class PlaylistItemWrapper:
         return self.item().display_type()
 
 
+# Remember!!! Using these three get wrapper functions will automatically add items into the cache!
 def get_item_wrapper(bot, **kwargs):
-    item = var.library.get_item(bot, **kwargs)
+    item = var.cache.get_item(bot, **kwargs)
     if 'user' not in kwargs:
         raise KeyError("Which user added this song?")
-    return PlaylistItemWrapper(var.library, item.id, kwargs['type'], kwargs['user'])
+    return PlaylistItemWrapper(var.cache, item.id, kwargs['type'], kwargs['user'])
 
 def get_item_wrapper_by_id(bot, id, user):
-    item = var.library.get_item_by_id(bot, id)
+    item = var.cache.get_item_by_id(bot, id)
     if item:
-        return PlaylistItemWrapper(var.library, item.id, item.type, user)
+        return PlaylistItemWrapper(var.cache, item.id, item.type, user)
     else:
         return None
 
 def get_item_wrappers_by_tags(bot, tags, user):
-    items = var.library.get_items_by_tags(bot, tags)
+    items = var.cache.get_items_by_tags(bot, tags)
     ret = []
     for item in items:
-        ret.append(PlaylistItemWrapper(var.library, item.id, item.type, user))
+        ret.append(PlaylistItemWrapper(var.cache, item.id, item.type, user))
     return ret
 
 def get_playlist(mode, _list=None, index=None):
@@ -235,7 +236,7 @@ class BasePlaylist(list):
                 counter += 1
 
         if counter == 0:
-            var.library.free(removed.id)
+            var.cache.free(removed.id)
         return removed
 
     def remove_by_id(self, id):
@@ -280,7 +281,7 @@ class BasePlaylist(list):
     def clear(self):
         self.version += 1
         self.current_index = -1
-        var.library.free_all()
+        var.cache.free_all()
         super().clear()
 
     def save(self):
@@ -330,7 +331,7 @@ class BasePlaylist(list):
             self.log.debug("playlist: validating %s" % item.format_debug_string())
             if not item.validate() or item.is_failed():
                 self.log.debug("playlist: validating failed.")
-                var.library.delete(item.id)
+                var.cache.delete(item.id)
                 self.remove_by_id(item.id)
 
         self.log.debug("playlist: validating finished.")
diff --git a/mumbleBot.py b/mumbleBot.py
index 7f7c99e..15ac25f 100644
--- a/mumbleBot.py
+++ b/mumbleBot.py
@@ -30,7 +30,7 @@ import media.file
 import media.radio
 import media.system
 from media.playlist import BasePlaylist
-from media.library import MusicLibrary
+from media.cache import MusicCache
 
 
 class MumbleBot:
@@ -347,7 +347,7 @@ class MumbleBot:
                 break
             else:
                 var.playlist.remove_by_id(next.id)
-                var.library.delete(next.id)
+                var.cache.delete(next.id)
 
 
     # =======================
@@ -407,7 +407,7 @@ class MumbleBot:
                                 self.send_msg(constants.strings('download_in_progress', item=current.format_short_string()))
                         else:
                             var.playlist.remove_by_id(current.id)
-                            var.library.delete(current.id)
+                            var.cache.delete(current.id)
                     else:
                         self._loop_status = 'Empty queue'
                 else:
@@ -639,7 +639,7 @@ if __name__ == '__main__':
     else:
         var.music_db = MusicDatabase(":memory:")
 
-    var.library = MusicLibrary(var.music_db)
+    var.cache = MusicCache(var.music_db)
 
     # load playback mode
     playback_mode = None
@@ -658,9 +658,9 @@ if __name__ == '__main__':
 
     if var.config.get("bot", "refresh_cache_on_startup", fallback=True)\
             or not var.db.has_option("dir_cache", "files"):
-        var.library.build_dir_cache(var.bot)
+        var.cache.build_dir_cache(var.bot)
     else:
-        var.library.load_dir_cache(var.bot)
+        var.cache.load_dir_cache(var.bot)
 
     # load playlist
     if var.config.getboolean('bot', 'save_playlist', fallback=True):
diff --git a/variables.py b/variables.py
index 606d516..9f8a605 100644
--- a/variables.py
+++ b/variables.py
@@ -1,6 +1,6 @@
 bot = None
 playlist = None
-library = None
+cache = None
 
 user = ""
 is_proxified = False