fix ModFolder not being JSON-serializable

docs/release-notes.md

@@ -12,6 +12,9 @@
   * In multiplayer, the game/SMAPI window titles now show whether you're the main player or a farmhand.
   * Fixed logged SMAPI errors not having line numbers on Linux/macOS.
 
+* For SMAPI toolkit users:
+  * Fixed `ModFolder` not being JSON-serializable.
+
 ## 3.18.3
 Released 09 April 2023 for Stardew Valley 1.5.6 or later.
 

src/SMAPI.Toolkit/Framework/ModScanning/ModFolder.cs

@@ -1,6 +1,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using Newtonsoft.Json;
 using StardewModdingAPI.Toolkit.Serialization.Models;
 using StardewModdingAPI.Toolkit.Utilities;
 
@@ -9,14 +10,25 @@ namespace StardewModdingAPI.Toolkit.Framework.ModScanning
     /// <summary>The info about a mod read from its folder.</summary>
     public class ModFolder
     {
+        /*********
+        ** Fields
+        *********/
+        /// <summary>The backing field for <see cref="Directory"/>.</summary>
+        private DirectoryInfo? DirectoryImpl;
+
+
         /*********
         ** Accessors
         *********/
         /// <summary>A suggested display name for the mod folder.</summary>
         public string DisplayName { get; }
 
+        /// <summary>The folder path containing the mod's manifest.json.</summary>
+        public string DirectoryPath { get; }
+
         /// <summary>The folder containing the mod's manifest.json.</summary>
-        public DirectoryInfo Directory { get; }
+        [JsonIgnore]
+        public DirectoryInfo Directory => this.DirectoryImpl ??= new DirectoryInfo(this.DirectoryPath);
 
         /// <summary>The mod type.</summary>
         public ModType Type { get; }
@@ -52,7 +64,8 @@ namespace StardewModdingAPI.Toolkit.Framework.ModScanning
         public ModFolder(DirectoryInfo root, DirectoryInfo directory, ModType type, Manifest? manifest, ModParseError manifestParseError, string? manifestParseErrorText)
         {
             // save info
-            this.Directory = directory;
+            this.DirectoryImpl = directory;
+            this.DirectoryPath = directory.FullName;
             this.Type = type;
             this.Manifest = manifest;
             this.ManifestParseError = manifestParseError;
@@ -64,6 +77,24 @@ namespace StardewModdingAPI.Toolkit.Framework.ModScanning
                 : PathUtilities.GetRelativePath(root.FullName, directory.FullName);
         }
 
+        /// <summary>Construct an instance.</summary>
+        /// <param name="displayName">A suggested display name for the mod folder.</param>
+        /// <param name="directoryPath">The folder path containing the mod's manifest.json.</param>
+        /// <param name="type">The mod type.</param>
+        /// <param name="manifest">The mod manifest.</param>
+        /// <param name="manifestParseError">The error which occurred parsing the manifest, if any.</param>
+        /// <param name="manifestParseErrorText">A human-readable message for the <paramref name="manifestParseError"/>, if any.</param>
+        [JsonConstructor]
+        public ModFolder(string displayName, string directoryPath, ModType type, Manifest? manifest, ModParseError manifestParseError, string? manifestParseErrorText)
+        {
+            this.DisplayName = displayName;
+            this.DirectoryPath = directoryPath;
+            this.Type = type;
+            this.Manifest = manifest;
+            this.ManifestParseError = manifestParseError;
+            this.ManifestParseErrorText = manifestParseErrorText;
+        }
+
         /// <summary>Get the update keys for a mod.</summary>
         /// <param name="manifest">The mod manifest.</param>
         public IEnumerable<string> GetUpdateKeys(Manifest manifest)