Move JsonIgnore specification to interface

osu.Game/Beatmaps/BeatmapDifficulty.cs

@@ -1,7 +1,6 @@
 // Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
-using Newtonsoft.Json;
 using osu.Game.Database;
 
 namespace osu.Game.Beatmaps
@@ -13,7 +12,6 @@ namespace osu.Game.Beatmaps
         /// </summary>
         public const float DEFAULT_DIFFICULTY = 5;
 
-        [JsonIgnore]
         public int ID { get; set; }
 
         public float DrainRate { get; set; } = DEFAULT_DIFFICULTY;

osu.Game/Beatmaps/BeatmapInfo.cs

@@ -15,7 +15,6 @@ namespace osu.Game.Beatmaps
     [Serializable]
     public class BeatmapInfo : IEquatable<BeatmapInfo>, IJsonSerializable, IHasPrimaryKey
     {
-        [JsonIgnore]
         public int ID { get; set; }
 
         public int BeatmapVersion;
@@ -29,7 +28,6 @@ namespace osu.Game.Beatmaps
             set => onlineBeatmapID = value > 0 ? value : null;
         }
 
-        [JsonIgnore]
         public int BeatmapSetInfoID { get; set; }
 
         public BeatmapSetOnlineStatus Status { get; set; } = BeatmapSetOnlineStatus.None;

osu.Game/Database/IHasPrimaryKey.cs

@@ -2,11 +2,13 @@
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
 using System.ComponentModel.DataAnnotations.Schema;
+using Newtonsoft.Json;
 
 namespace osu.Game.Database
 {
     public interface IHasPrimaryKey
     {
+        [JsonIgnore]
         [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
         int ID { get; set; }
     }

osu.Game/Rulesets/RulesetInfo.cs

@@ -2,15 +2,12 @@
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
 using System;
-using System.ComponentModel.DataAnnotations.Schema;
 using Newtonsoft.Json;
 
 namespace osu.Game.Rulesets
 {
     public class RulesetInfo : IEquatable<RulesetInfo>
     {
-        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
-        [JsonIgnore]
         public int? ID { get; set; }
 
         public string Name { get; set; }

osu.Game/Scoring/ScoreInfo.cs

@@ -17,7 +17,6 @@ namespace osu.Game.Scoring
 {
     public class ScoreInfo : IHasFiles<ScoreFileInfo>, IHasPrimaryKey, ISoftDelete
     {
-        [JsonIgnore]
         public int ID { get; set; }
 
         public ScoreRank Rank { get; set; }