Health propagation between API an UI not possible due to sealed & un(de)serializable

[ibruynin]

I'm trying to propagate the degraded health from the API to the UI (using that API) as follows:

API:8080/health returns JsonSerializer.Serialize<HealthReport>(result)

UI:8080/health returns health info based on the result of the API

var s = await response.Content.ReadAsStringAsync();                
var hr = JsonNode.Parse(s).AsObject();
var entries = hr["Entries"];
var entry = entries["API_XYZ"];
var hres = Int32.Parse(entry["Status"].ToString());
HealthStatus status = (HealthStatus)hres;
return status switch
{
    HealthStatus.Healthy => HealthCheckResult.Healthy("Degraded API up"),
    HealthStatus.Degraded => HealthCheckResult.Degraded("Degraded API up, but degraded"),
    HealthStatus.Unhealthy => HealthCheckResult.Unhealthy("Degraded API unavailable")
};

It would be cleaner (and more typesafe) if the following was possible:

var s = await response.Content.ReadAsStringAsync();                
var hr = JsonSerializer.Deserialize<HealthReport>(s);

But that's not possible due to the lack of a default constructor:
System.NotSupportedException: 'Deserialization of types without a parameterless constructor, a singular parameterized constructor, or a parameterized constructor annotated with 'JsonConstructorAttribute' is not supported. Type 'Microsoft.Extensions.Diagnostics.HealthChecks.HealthReport'.

Extending the type is also not a workaround, since the class is sealed.

Are we trying to do something that's not intended to do?
Thoughts welcome.

[surgicalcoder]

@ibruynin I ran into the same problem, I managed to get around it by getting GH Copilot to write a custom JSON Converter:

public class HealthReportJsonConverter : JsonConverter<HealthReport>
{
    public override HealthReport Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        if (reader.TokenType != JsonTokenType.StartObject)
        {
            throw new JsonException();
        }

        var entries = new Dictionary<string, HealthReportEntry>();
        TimeSpan totalDuration = TimeSpan.Zero;
        HealthStatus status = HealthStatus.Healthy;

        while (reader.Read())
        {
            if (reader.TokenType == JsonTokenType.EndObject)
            {
                return new HealthReport(entries, status, totalDuration);
            }

            if (reader.TokenType != JsonTokenType.PropertyName)
            {
                throw new JsonException();
            }

            string propertyName = reader.GetString();
            reader.Read();

            switch (propertyName.ToLowerInvariant())
            {
                case "entries":
                    entries = JsonSerializer.Deserialize<Dictionary<string, HealthReportEntry>>(ref reader, new JsonSerializerOptions { Converters = { new HealthReportEntryJsonConverter() } });
                    break;
                case "totalduration":
                    totalDuration = JsonSerializer.Deserialize<TimeSpan>(ref reader, options);
                    break;
                case "status":
                    status = (HealthStatus)reader.GetInt32();
                    break;
                default:
                    throw new JsonException($"Unexpected property: {propertyName}");
            }
        }

        throw new JsonException();
    }

    public override void Write(Utf8JsonWriter writer, HealthReport value, JsonSerializerOptions options)
    {
        writer.WriteStartObject();

        writer.WritePropertyName("Entries");
        JsonSerializer.Serialize(writer, value.Entries, options);

        writer.WritePropertyName("TotalDuration");
        JsonSerializer.Serialize(writer, value.TotalDuration, options);

        writer.WritePropertyName("Status");
        writer.WriteNumberValue((int)value.Status);

        writer.WriteEndObject();
    }
}


public class HealthReportEntryJsonConverter : JsonConverter<HealthReportEntry>
{
    public override HealthReportEntry Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        if (reader.TokenType != JsonTokenType.StartObject)
        {
            throw new JsonException();
        }

        HealthStatus status = HealthStatus.Healthy;
        string? description = null;
        TimeSpan duration = TimeSpan.Zero;
        Exception? exception = null;
        var data = new Dictionary<string, object>();
        IEnumerable<string>? tags = null;

        while (reader.Read())
        {
            if (reader.TokenType == JsonTokenType.EndObject)
            {
                return new HealthReportEntry(status, description, duration, exception, data, tags);
            }

            if (reader.TokenType != JsonTokenType.PropertyName)
            {
                throw new JsonException();
            }

            string propertyName = reader.GetString();
            reader.Read();

            switch (propertyName.ToLowerInvariant())
            {
                case "status":
                    status = (HealthStatus)reader.GetInt32();
                    break;
                case "description":
                    description = reader.GetString();
                    break;
                case "duration":
                    duration = JsonSerializer.Deserialize<TimeSpan>(ref reader, options);
                    break;
                case "exception":
                    exception = JsonSerializer.Deserialize<Exception>(ref reader, options);
                    break;
                case "data":
                    data = JsonSerializer.Deserialize<Dictionary<string, object>>(ref reader, options);
                    break;
                case "tags":
                    tags = JsonSerializer.Deserialize<IEnumerable<string>>(ref reader, options);
                    break;
                default:
                    throw new JsonException($"Unexpected property: {propertyName}");
            }
        }

        throw new JsonException();
    }

    public override void Write(Utf8JsonWriter writer, HealthReportEntry value, JsonSerializerOptions options)
    {
        writer.WriteStartObject();

        writer.WritePropertyName("Status");
        writer.WriteNumberValue((int)value.Status);

        writer.WritePropertyName("Description");
        writer.WriteStringValue(value.Description);

        writer.WritePropertyName("Duration");
        JsonSerializer.Serialize(writer, value.Duration, options);

        writer.WritePropertyName("Exception");
        JsonSerializer.Serialize(writer, value.Exception, options);

        writer.WritePropertyName("Data");
        JsonSerializer.Serialize(writer, value.Data, options);

        writer.WritePropertyName("Tags");
        JsonSerializer.Serialize(writer, value.Tags, options);

        writer.WriteEndObject();
    }
}

Seems to have done the trick for me, hope it helps.