JetStream enum PascalCase serializer (#225)

* JetStream enum PascalCase serializer

System.Text.Json serializer has some difficult settings serializing enums.
Before we just relied on unconventional property names in code but proper
way is to use PascalCase. Unfortunately the JSON options also did not allow
snake_case conversion also I didn't want to force System.Text.Json v8 onto
net6.0 targets (if that supports it). Hence we now have a JetStream specific
JSON enum convertor.

* net8.0 supports snake_case enums

NATS.Client.sln.DotSettings

@@ -9,4 +9,5 @@
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=HMSG/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=HPUB/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=Msgs/@EntryIndexedValue">True</s:Boolean>
-	<s:Boolean x:Key="/Default/UserDictionary/Words/=Nuid/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Nuid/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/UserDictionary/Words/=Workqueue/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>

sandbox/Example.JetStream.PullConsumer/Program.cs

@@ -19,7 +19,7 @@
 
 var js = new NatsJSContext(nats);
 
-var consumer = await js.CreateConsumerAsync("s1", new ConsumerConfig { Name = "c1", DurableName = "c1", AckPolicy = ConsumerConfigAckPolicy.@explicit });
+var consumer = await js.CreateConsumerAsync("s1", new ConsumerConfig { Name = "c1", DurableName = "c1", AckPolicy = ConsumerConfigAckPolicy.Explicit });
 
 var idle = TimeSpan.FromSeconds(5);
 var expires = TimeSpan.FromSeconds(10);

src/NATS.Client.JetStream/Internal/NatsJSJsonSerializer.cs

@@ -1,3 +1,4 @@
+using System.Text.Json;
 using System.Text.Json.Serialization;
 using NATS.Client.Core;
 using NATS.Client.JetStream.Models;
@@ -6,7 +7,23 @@ namespace NATS.Client.JetStream.Internal;
 
 internal static class NatsJSJsonSerializer<T>
 {
+#if NET6_0
     public static readonly INatsSerializer<T> Default = new NatsJsonContextSerializer<T>(NatsJSJsonSerializerContext.Default);
+#else
+    public static readonly INatsSerializer<T> Default = new NatsJsonContextSerializer<T>(new NatsJSJsonSerializerContext(new JsonSerializerOptions
+    {
+        Converters =
+        {
+            new JsonStringEnumConverter<ConsumerConfigDeliverPolicy>(JsonNamingPolicy.SnakeCaseLower),
+            new JsonStringEnumConverter<ConsumerConfigAckPolicy>(JsonNamingPolicy.SnakeCaseLower),
+            new JsonStringEnumConverter<ConsumerConfigReplayPolicy>(JsonNamingPolicy.SnakeCaseLower),
+            new JsonStringEnumConverter<StreamConfigCompression>(JsonNamingPolicy.SnakeCaseLower),
+            new JsonStringEnumConverter<StreamConfigDiscard>(JsonNamingPolicy.SnakeCaseLower),
+            new JsonStringEnumConverter<StreamConfigRetention>(JsonNamingPolicy.SnakeCaseLower),
+            new JsonStringEnumConverter<StreamConfigStorage>(JsonNamingPolicy.SnakeCaseLower),
+        },
+    }));
+#endif
 }
 
 [JsonSerializable(typeof(AccountInfoResponse))]
@@ -86,3 +103,218 @@ internal static class NatsJSJsonSerializer<T>
 internal partial class NatsJSJsonSerializerContext : JsonSerializerContext
 {
 }
+
+#if NET6_0
+internal class NatsJSJsonStringEnumConverter<TEnum> : JsonConverter<TEnum>
+    where TEnum : struct, Enum
+{
+    public override TEnum Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+    {
+        if (reader.TokenType != JsonTokenType.String)
+        {
+            throw new InvalidOperationException();
+        }
+
+        var stringValue = reader.GetString();
+
+        if (typeToConvert == typeof(ConsumerConfigDeliverPolicy))
+        {
+            switch (stringValue)
+            {
+            case "all":
+                return (TEnum)(object)ConsumerConfigDeliverPolicy.All;
+            case "last":
+                return (TEnum)(object)ConsumerConfigDeliverPolicy.Last;
+            case "new":
+                return (TEnum)(object)ConsumerConfigDeliverPolicy.New;
+            case "by_start_sequence":
+                return (TEnum)(object)ConsumerConfigDeliverPolicy.ByStartSequence;
+            case "by_start_time":
+                return (TEnum)(object)ConsumerConfigDeliverPolicy.ByStartTime;
+            case "last_per_subject":
+                return (TEnum)(object)ConsumerConfigDeliverPolicy.LastPerSubject;
+            }
+        }
+
+        if (typeToConvert == typeof(ConsumerConfigAckPolicy))
+        {
+            switch (stringValue)
+            {
+            case "none":
+                return (TEnum)(object)ConsumerConfigAckPolicy.None;
+            case "all":
+                return (TEnum)(object)ConsumerConfigAckPolicy.All;
+            case "explicit":
+                return (TEnum)(object)ConsumerConfigAckPolicy.Explicit;
+            }
+        }
+
+        if (typeToConvert == typeof(ConsumerConfigReplayPolicy))
+        {
+            switch (stringValue)
+            {
+            case "instant":
+                return (TEnum)(object)ConsumerConfigReplayPolicy.Instant;
+            case "original":
+                return (TEnum)(object)ConsumerConfigReplayPolicy.Original;
+            }
+        }
+
+        if (typeToConvert == typeof(StreamConfigCompression))
+        {
+            switch (stringValue)
+            {
+            case "none":
+                return (TEnum)(object)StreamConfigCompression.None;
+            case "s2":
+                return (TEnum)(object)StreamConfigCompression.S2;
+            }
+        }
+
+        if (typeToConvert == typeof(StreamConfigDiscard))
+        {
+            switch (stringValue)
+            {
+            case "old":
+                return (TEnum)(object)StreamConfigDiscard.Old;
+            case "new":
+                return (TEnum)(object)StreamConfigDiscard.New;
+            }
+        }
+
+        if (typeToConvert == typeof(StreamConfigRetention))
+        {
+            switch (stringValue)
+            {
+            case "limits":
+                return (TEnum)(object)StreamConfigRetention.Limits;
+            case "interest":
+                return (TEnum)(object)StreamConfigRetention.Interest;
+            case "workqueue":
+                return (TEnum)(object)StreamConfigRetention.Workqueue;
+            }
+        }
+
+        if (typeToConvert == typeof(StreamConfigStorage))
+        {
+            switch (stringValue)
+            {
+            case "file":
+                return (TEnum)(object)StreamConfigStorage.File;
+            case "memory":
+                return (TEnum)(object)StreamConfigStorage.Memory;
+            }
+        }
+
+        throw new InvalidOperationException($"Reading unknown enum type {typeToConvert.Name} or value {stringValue}");
+    }
+
+    public override void Write(Utf8JsonWriter writer, TEnum value, JsonSerializerOptions options)
+    {
+        if (value is ConsumerConfigDeliverPolicy consumerConfigDeliverPolicy)
+        {
+            switch (consumerConfigDeliverPolicy)
+            {
+            case ConsumerConfigDeliverPolicy.All:
+                writer.WriteStringValue("all");
+                return;
+            case ConsumerConfigDeliverPolicy.Last:
+                writer.WriteStringValue("last");
+                return;
+            case ConsumerConfigDeliverPolicy.New:
+                writer.WriteStringValue("new");
+                return;
+            case ConsumerConfigDeliverPolicy.ByStartSequence:
+                writer.WriteStringValue("by_start_sequence");
+                return;
+            case ConsumerConfigDeliverPolicy.ByStartTime:
+                writer.WriteStringValue("by_start_time");
+                return;
+            case ConsumerConfigDeliverPolicy.LastPerSubject:
+                writer.WriteStringValue("last_per_subject");
+                return;
+            }
+        }
+        else if (value is ConsumerConfigAckPolicy consumerConfigAckPolicy)
+        {
+            switch (consumerConfigAckPolicy)
+            {
+            case ConsumerConfigAckPolicy.None:
+                writer.WriteStringValue("none");
+                return;
+            case ConsumerConfigAckPolicy.All:
+                writer.WriteStringValue("all");
+                return;
+            case ConsumerConfigAckPolicy.Explicit:
+                writer.WriteStringValue("explicit");
+                return;
+            }
+        }
+        else if (value is ConsumerConfigReplayPolicy consumerConfigReplayPolicy)
+        {
+            switch (consumerConfigReplayPolicy)
+            {
+            case ConsumerConfigReplayPolicy.Instant:
+                writer.WriteStringValue("instant");
+                return;
+            case ConsumerConfigReplayPolicy.Original:
+                writer.WriteStringValue("original");
+                return;
+            }
+        }
+        else if (value is StreamConfigCompression streamConfigCompression)
+        {
+            switch (streamConfigCompression)
+            {
+            case StreamConfigCompression.None:
+                writer.WriteStringValue("none");
+                return;
+            case StreamConfigCompression.S2:
+                writer.WriteStringValue("s2");
+                return;
+            }
+        }
+        else if (value is StreamConfigDiscard streamConfigDiscard)
+        {
+            switch (streamConfigDiscard)
+            {
+            case StreamConfigDiscard.Old:
+                writer.WriteStringValue("old");
+                return;
+            case StreamConfigDiscard.New:
+                writer.WriteStringValue("new");
+                return;
+            }
+        }
+        else if (value is StreamConfigRetention streamConfigRetention)
+        {
+            switch (streamConfigRetention)
+            {
+            case StreamConfigRetention.Limits:
+                writer.WriteStringValue("limits");
+                return;
+            case StreamConfigRetention.Interest:
+                writer.WriteStringValue("interest");
+                return;
+            case StreamConfigRetention.Workqueue:
+                writer.WriteStringValue("workqueue");
+                return;
+            }
+        }
+        else if (value is StreamConfigStorage streamConfigStorage)
+        {
+            switch (streamConfigStorage)
+            {
+            case StreamConfigStorage.File:
+                writer.WriteStringValue("file");
+                return;
+            case StreamConfigStorage.Memory:
+                writer.WriteStringValue("memory");
+                return;
+            }
+        }
+
+        throw new InvalidOperationException($"Writing unknown enum value {value.GetType().Name}.{value}");
+    }
+}
+#endif

src/NATS.Client.JetStream/Internal/NatsJSOrderedPushConsumer.cs

@@ -36,7 +36,7 @@ internal record NatsJSOrderedPushConsumerOpts
     /// </summary>
     public TimeSpan IdleHeartbeat { get; init; } = TimeSpan.FromSeconds(5);
 
-    public ConsumerConfigDeliverPolicy DeliverPolicy { get; init; } = ConsumerConfigDeliverPolicy.all;
+    public ConsumerConfigDeliverPolicy DeliverPolicy { get; init; } = ConsumerConfigDeliverPolicy.All;
 
     public bool HeadersOnly { get; init; } = false;
 }
@@ -338,8 +338,8 @@ private async ValueTask CreatePushConsumer(string origin)
         var config = new ConsumerConfig
         {
             Name = Consumer,
-            DeliverPolicy = ConsumerConfigDeliverPolicy.all,
-            AckPolicy = ConsumerConfigAckPolicy.none,
+            DeliverPolicy = ConsumerConfigDeliverPolicy.All,
+            AckPolicy = ConsumerConfigAckPolicy.None,
             DeliverSubject = _sub.Subject,
             FilterSubject = _filter,
             FlowControl = true,
@@ -348,15 +348,15 @@ private async ValueTask CreatePushConsumer(string origin)
             MaxDeliver = 1,
             MemStorage = true,
             NumReplicas = 1,
-            ReplayPolicy = ConsumerConfigReplayPolicy.instant,
+            ReplayPolicy = ConsumerConfigReplayPolicy.Instant,
         };
 
         config.DeliverPolicy = _opts.DeliverPolicy;
         config.HeadersOnly = _opts.HeadersOnly;
 
         if (sequence > 0)
         {
-            config.DeliverPolicy = ConsumerConfigDeliverPolicy.by_start_sequence;
+            config.DeliverPolicy = ConsumerConfigDeliverPolicy.ByStartSequence;
             config.OptStartSeq = sequence + 1;
         }
 

src/NATS.Client.JetStream/Models/ConsumerConfig.cs

@@ -1,3 +1,5 @@
+using NATS.Client.JetStream.Internal;
+
 namespace NATS.Client.JetStream.Models;
 
 public record ConsumerConfig
@@ -10,16 +12,14 @@ public ConsumerConfig(string name)
     {
         Name = name;
         DurableName = name;
-        AckPolicy = ConsumerConfigAckPolicy.@explicit;
+        AckPolicy = ConsumerConfigAckPolicy.Explicit;
     }
 
     [System.Text.Json.Serialization.JsonPropertyName("deliver_policy")]
     [System.Text.Json.Serialization.JsonIgnore(Condition = System.Text.Json.Serialization.JsonIgnoreCondition.Never)]
     [System.ComponentModel.DataAnnotations.Required(AllowEmptyStrings = true)]
 #if NET6_0
-    [System.Text.Json.Serialization.JsonConverter(typeof(System.Text.Json.Serialization.JsonStringEnumConverter))]
-#else
-    [System.Text.Json.Serialization.JsonConverter(typeof(System.Text.Json.Serialization.JsonStringEnumConverter<ConsumerConfigDeliverPolicy>))]
+    [System.Text.Json.Serialization.JsonConverter(typeof(NatsJSJsonStringEnumConverter<ConsumerConfigDeliverPolicy>))]
 #endif
     public ConsumerConfigDeliverPolicy DeliverPolicy { get; set; } = default!;
 
@@ -67,11 +67,9 @@ public ConsumerConfig(string name)
     [System.Text.Json.Serialization.JsonIgnore(Condition = System.Text.Json.Serialization.JsonIgnoreCondition.Never)]
     [System.ComponentModel.DataAnnotations.Required(AllowEmptyStrings = true)]
 #if NET6_0
-    [System.Text.Json.Serialization.JsonConverter(typeof(System.Text.Json.Serialization.JsonStringEnumConverter))]
-#else
-    [System.Text.Json.Serialization.JsonConverter(typeof(System.Text.Json.Serialization.JsonStringEnumConverter<ConsumerConfigAckPolicy>))]
+    [System.Text.Json.Serialization.JsonConverter(typeof(NatsJSJsonStringEnumConverter<ConsumerConfigAckPolicy>))]
 #endif
-    public ConsumerConfigAckPolicy AckPolicy { get; set; } = ConsumerConfigAckPolicy.none;
+    public ConsumerConfigAckPolicy AckPolicy { get; set; } = ConsumerConfigAckPolicy.None;
 
     /// <summary>
     /// How long (in nanoseconds) to allow messages to remain un-acknowledged before attempting redelivery
@@ -107,11 +105,9 @@ public ConsumerConfig(string name)
     [System.Text.Json.Serialization.JsonIgnore(Condition = System.Text.Json.Serialization.JsonIgnoreCondition.Never)]
     [System.ComponentModel.DataAnnotations.Required(AllowEmptyStrings = true)]
 #if NET6_0
-    [System.Text.Json.Serialization.JsonConverter(typeof(System.Text.Json.Serialization.JsonStringEnumConverter))]
-#else
-    [System.Text.Json.Serialization.JsonConverter(typeof(System.Text.Json.Serialization.JsonStringEnumConverter<ConsumerConfigReplayPolicy>))]
+    [System.Text.Json.Serialization.JsonConverter(typeof(NatsJSJsonStringEnumConverter<ConsumerConfigReplayPolicy>))]
 #endif
-    public ConsumerConfigReplayPolicy ReplayPolicy { get; set; } = NATS.Client.JetStream.Models.ConsumerConfigReplayPolicy.instant;
+    public ConsumerConfigReplayPolicy ReplayPolicy { get; set; } = NATS.Client.JetStream.Models.ConsumerConfigReplayPolicy.Instant;
 
     [System.Text.Json.Serialization.JsonPropertyName("sample_freq")]
     [System.Text.Json.Serialization.JsonIgnore(Condition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingDefault)]

src/NATS.Client.JetStream/Models/ConsumerConfigAckPolicy.cs

@@ -1,15 +1,8 @@
 namespace NATS.Client.JetStream.Models;
 
-// TODO: enum member naming with JSON serialization isn't working for some reason
-#pragma warning disable SA1300
 public enum ConsumerConfigAckPolicy
 {
-    [System.Runtime.Serialization.EnumMember(Value = @"none")]
-    none = 0,
-
-    [System.Runtime.Serialization.EnumMember(Value = @"all")]
-    all = 1,
-
-    [System.Runtime.Serialization.EnumMember(Value = @"explicit")]
-    @explicit = 2,
+    None = 0,
+    All = 1,
+    Explicit = 2,
 }