1 files changed, 57 insertions, 0 deletions
diff --git a/src/Cepis/LenientStringConverter.cs b/src/Cepis/LenientStringConverter.cs
new file mode 100644
index 0000000..f76c917
--- /dev/null
+++ b/src/Cepis/LenientStringConverter.cs
@@ -0,0 +1,57 @@
+using System.Buffers;
+using System.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Cepis;
+
+/// <summary>
+/// Reads any scalar as a string, and a JSON <c>null</c> as the empty string.
+/// </summary>
+/// <remarks>
+/// The API documents every text field as a string and an absent one as
+/// <c>""</c>, never null. This converter makes a client that meets a
+/// <c>null</c>, or a code sent as a number, degrade to the documented shape
+/// instead of throwing: none of those is worth failing a whole lookup over.
+/// </remarks>
+internal sealed class LenientStringConverter : JsonConverter<string>
+{
+    public override bool HandleNull => true;
+
+    public override string Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        switch (reader.TokenType)
+        {
+            case JsonTokenType.String:
+                return reader.GetString() ?? "";
+            case JsonTokenType.Null:
+                return "";
+            case JsonTokenType.True:
+                return "true";
+            case JsonTokenType.False:
+                return "false";
+            case JsonTokenType.Number:
+                var raw = reader.HasValueSequence
+                    ? reader.ValueSequence.ToArray()
+                    : reader.ValueSpan.ToArray();
+                return Encoding.UTF8.GetString(raw);
+            default:
+                throw new JsonException($"expected a string, got {reader.TokenType}");
+        }
+    }
+
+    public override void Write(Utf8JsonWriter writer, string value, JsonSerializerOptions options)
+    {
+        ArgumentNullException.ThrowIfNull(writer);
+        writer.WriteStringValue(value);
+    }
+
+    public override string ReadAsPropertyName(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) =>
+        reader.GetString() ?? "";
+
+    public override void WriteAsPropertyName(Utf8JsonWriter writer, string value, JsonSerializerOptions options)
+    {
+        ArgumentNullException.ThrowIfNull(writer);
+        writer.WritePropertyName(value);
+    }
+}