Move MongoDB classes into a seperate db module (#62)

* move album class into mongodb dir

* inherit AlbumMethods at DB Initialization level

* move album -> db/mongodb

* move mongodb classes into separate package

server/app/db/mongodb/playlists.py

@@ -0,0 +1,78 @@
+"""
+This file contains the Playlists class for interacting with the playlist documents in MongoDB.
+"""
+from app.db.mongodb import convert_many
+from app.db.mongodb import convert_one
+from app.db.mongodb import MongoPlaylists
+from app.helpers import create_new_date
+from bson import ObjectId
+
+
+class Playlists(MongoPlaylists):
+    """
+    The class for all playlist-related database operations.
+    """
+
+    def insert_playlist(self, playlist: dict) -> None:
+        """
+        Inserts a new playlist object into the database.
+        """
+        return self.collection.update_one(
+            {
+                "name": playlist["name"]
+            },
+            {
+                "$set": playlist
+            },
+            upsert=True,
+        ).upserted_id
+
+    def get_all_playlists(self) -> list:
+        """
+        Returns all the playlists in the database.
+        """
+        playlists = self.collection.find()
+        return convert_many(playlists)
+
+    def get_playlist_by_id(self, id: str) -> dict:
+        """
+        Returns a single playlist matching the id in the query params.
+        """
+        playlist = self.collection.find_one({"_id": ObjectId(id)})
+        return convert_one(playlist)
+
+    def add_track_to_playlist(self, playlistid: str, track: dict) -> None:
+        """
+        Adds a track to a playlist.
+        """
+        date = create_new_date()
+
+        return self.collection.update_one(
+            {
+                "_id": ObjectId(playlistid),
+            },
+            {
+                "$push": {
+                    "pre_tracks": track
+                },
+                "$set": {
+                    "lastUpdated": date
+                }
+            },
+        )
+
+    def get_playlist_by_name(self, name: str) -> dict:
+        """
+        Returns a single playlist matching the name in the query params.
+        """
+        playlist = self.collection.find_one({"name": name})
+        return convert_one(playlist)
+
+    def update_playlist(self, playlistid: str, playlist: dict) -> None:
+        """
+        Updates a playlist.
+        """
+        return self.collection.update_one(
+            {"_id": ObjectId(playlistid)},
+            {"$set": playlist},
+        )