refactor: Simplify field initialization in Songs and SongData records

Author: Yushu2606

src/Prober/DivingFish/Models/Song.cs

@@ -34,8 +34,6 @@ public record Song
 
 internal record Songs
 {
-    private static Songs? _shared;
-
     private readonly DateTimeOffset _pullTime;
     private readonly ImmutableArray<Song> _songs;
     private readonly FrozenDictionary<string, Song> _songsById;
@@ -51,15 +49,15 @@ private static Songs SharedSongs
     {
         get
         {
-            if (_shared is not null && DateTimeOffset.Now.AddHours(10).Date == _shared._pullTime.AddHours(10).Date)
+            if (field is not null && DateTimeOffset.Now.AddHours(10).Date == field._pullTime.AddHours(10).Date)
             {
-                return _shared;
+                return field;
             }
 
             DfResourceClient resource = new();
-            _shared = (Songs)resource.GetSongsAsync().Result;
+            field = (Songs)resource.GetSongsAsync().Result;
 
-            return _shared;
+            return field;
         }
     }
 

src/Prober/Lxns/Models/SongData.cs

@@ -7,10 +7,6 @@ public record SongData
 {
     private readonly DateTimeOffset _pullTime = DateTimeOffset.Now;
 
-    private FrozenDictionary<int, Song>? _songsById;
-
-    private FrozenDictionary<int, Version>? _versionsByGroup;
-
     [JsonPropertyName("songs")]
     public required List<Song> Songs { get; set; }
 
@@ -20,9 +16,9 @@ public record SongData
     [JsonPropertyName("versions")]
     public required List<Version> Versions { get; set; }
 
-    public FrozenDictionary<int, Song> SongsById => _songsById ??= Songs.ToFrozenDictionary(x => x.Id);
+    public FrozenDictionary<int, Song> SongsById => field ??= Songs.ToFrozenDictionary(x => x.Id);
 
-    public FrozenDictionary<int, Version> VersionsByGroup => _versionsByGroup ??=
+    public FrozenDictionary<int, Version> VersionsByGroup => field ??=
         Versions.GroupBy(x => x.VersionNumber / 100).ToFrozenDictionary(x => x.Key, x => x.First());
 
     public static SongData Shared