fix: serialize and deserialize enum members correctly

Author: kyleratti

WebApi/Models/SerializableLinkType.cs

@@ -1,15 +1,15 @@
-using System.Runtime.Serialization;
-using System.Text.Json.Serialization;
+using System.Text.Json.Serialization;
+using WebApi.Util;
 
 #pragma warning disable CS1591
 
 namespace WebApi.Models;
 
-[JsonConverter(typeof(JsonStringEnumConverter))]
+[JsonConverter(typeof(JsonEnumConverter<SerializableLinkType>))]
 public enum SerializableLinkType
 {
-	[EnumMember(Value = "mirror")]
+	[JsonEnumValue("mirror")]
 	Mirror = 1,
-	[EnumMember(Value = "download")]
+	[JsonEnumValue("download")]
 	Download = 2
 }

WebApi/Util/JsonEnumConverter.cs

@@ -0,0 +1,87 @@
+using System.Reflection;
+using System.Runtime.Serialization;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using FruityFoundation.Base.Structures;
+
+namespace WebApi.Util;
+
+/// <summary>
+/// A serializable and deserializable value for an enum value
+/// </summary>
+[AttributeUsage(AttributeTargets.Field, AllowMultiple = false, Inherited = true)]
+public class JsonEnumValueAttribute : Attribute
+{
+	/// <summary>
+	/// The string value.
+	/// </summary>
+	public string Value { get; }
+	/// <summary>
+	/// The comparison mode to use if performing string comparisons against <see cref="Value"/>.
+	/// </summary>
+	public StringComparison ComparisonMode { get; }
+
+	/// <summary>
+	/// A serializable and deserializable value for an enum value
+	/// </summary>
+	/// <param name="value">The string value of this member</param>
+	/// <param name="comparisonMode">The comparison mode to use.</param>
+	public JsonEnumValueAttribute(string value, StringComparison comparisonMode = StringComparison.OrdinalIgnoreCase)
+	{
+		Value = value;
+		ComparisonMode = comparisonMode;
+	}
+}
+
+/// <summary>
+/// Serialize and deserialize enums using string members
+/// </summary>
+public class JsonEnumConverter<T> : JsonConverter<T> where T : struct, Enum
+{
+	/// <inheritdoc />
+	public override T Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+	{
+		var jsonValue = reader.GetString();
+
+		if (jsonValue is null)
+			throw new SerializationException("value was null");
+
+		if (!FindEnumByJsonValue(jsonValue).Try(out var enumValue))
+			throw new SerializationException($"Unable to map value to type ({typeof(T).FullName}): {jsonValue}");
+
+		return enumValue;
+	}
+
+	/// <inheritdoc />
+	public override void Write(Utf8JsonWriter writer, T value, JsonSerializerOptions options)
+	{
+		writer.WriteStringValue(GetJsonValueForEnum(value));
+	}
+
+	/// <inheritdoc />
+	public override bool CanConvert(Type typeToConvert) =>
+		typeToConvert.IsEnum;
+
+	private static string GetJsonValueForEnum(T enumValue) =>
+		FindJsonValueForEnum(enumValue)
+			.Map(x => x.Value)
+			.OrThrow($"Missing {nameof(JsonEnumValueAttribute)} on member: {enumValue.GetType().FullName}.{enumValue.ToString("G")}");
+
+	private static Maybe<JsonEnumValueAttribute> FindJsonValueForEnum(T enumValue)
+	{
+		var enumName = Enum.GetName(enumValue.GetType(), enumValue) ?? throw new ApplicationException($"Unable to find enum member {enumValue} on type {enumValue.GetType().FullName}");
+
+		return enumValue.GetType()
+			.GetMember(enumName)
+			.Select(x => x.GetCustomAttribute<JsonEnumValueAttribute>(inherit: true))
+			.Where(x => x is not null)
+			.Cast<JsonEnumValueAttribute>()
+			.FirstOrEmpty();
+	}
+
+	private static Maybe<T> FindEnumByJsonValue(string input) =>
+		Enum.GetValues<T>()
+			.Select(x => (EnumValue: x, JsonValue: FindJsonValueForEnum(x)))
+			.FirstOrEmpty(x => x.JsonValue.Try(out var jsonValue) && jsonValue.Value.Equals(input, jsonValue.ComparisonMode))
+			.Map(x => x.EnumValue);
+}