Add support for "connection_init" 's payload

src/Linq2GraphQL.Client.Subscriptions/GraphSubscriptionExecute.cs

@@ -26,7 +26,7 @@ public async Task<IObservable<TResult>> StartAsync()
             return sseClient.Subscription.Select(e => ConvertResult(queryExecutor.ProcessResponse(e, QueryNode.Name, payload.Query)));
         }
 
-        var wsClient = new WSClient(client.SubscriptionUrl, client.SubscriptionProtocol, payload);
+        var wsClient = new WSClient(client, payload);
         await wsClient.Start();
         return wsClient.Subscription.Select(e => ConvertResult(queryExecutor.ProcessResponse(e, QueryNode.Name, payload.Query)));
     }

src/Linq2GraphQL.Client.Subscriptions/SSEClient.cs

@@ -1,4 +1,5 @@
 using System.Net.Http.Headers;
+using System.Net.Mime;
 using System.Reactive.Linq;
 using System.Reactive.Subjects;
 using System.Text;
@@ -34,7 +35,7 @@ public async Task Start()
 
         var request = new HttpRequestMessage(HttpMethod.Post, "")
         {
-            Content = new StringContent(json, Encoding.UTF8, "application/json")
+            Content = new StringContent(json, Encoding.UTF8, MediaTypeNames.Application.Json)
         };
 
         request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("text/event-stream"));

src/Linq2GraphQL.Client.Subscriptions/SubscribeCommands.cs

@@ -0,0 +1,8 @@
+namespace Linq2GraphQL.Client.Subscriptions
+{
+    internal class SubscribeCommands
+    {
+        internal const string SUBSCRIBE = "subscribe";
+        internal const string START = "start";
+    }
+}

src/Linq2GraphQL.Client.Subscriptions/SubscriptionProtocols.cs

@@ -0,0 +1,8 @@
+namespace Linq2GraphQL.Client.Subscriptions
+{
+    internal static class SubscriptionProtocols
+    {
+        internal const string GRAPGQL_TRANSPORT_WS = "graphql-transport-ws";
+        internal const string GRAPHQL_WS = "graphql-ws";
+    }
+}

src/Linq2GraphQL.Client.Subscriptions/WSClient.cs

@@ -1,4 +1,5 @@
-using System.Net.WebSockets;
+using System.Diagnostics;
+using System.Net.WebSockets;
 using System.Reactive.Linq;
 using System.Reactive.Subjects;
 using System.Text.Json;
@@ -9,19 +10,17 @@ namespace Linq2GraphQL.Client.Subscriptions;
 
 public class WSClient : IAsyncDisposable
 {
+    private readonly GraphClient _graphClient;
     private readonly GraphQLRequest payload;
-    private readonly SubscriptionProtocol subscriptionProtocol;
 
     private readonly Subject<string> subscriptionSubject = new();
-    private readonly string url;
     private readonly WebsocketClient client;
 
     private readonly JsonSerializerOptions jsonOptions;
 
-    public WSClient(string url, SubscriptionProtocol subprotocol, GraphQLRequest payload)
+    public WSClient(GraphClient graphClient, GraphQLRequest payload)
     {
-        this.url = url;
-        subscriptionProtocol = subprotocol;
+        _graphClient = graphClient;
         this.payload = payload;
         jsonOptions = new JsonSerializerOptions
         {
@@ -35,7 +34,7 @@ public WSClient(string url, SubscriptionProtocol subprotocol, GraphQLRequest pay
             return ws;
         });
 
-        client = new WebsocketClient(new Uri(url), factory)
+        client = new WebsocketClient(new Uri(_graphClient.SubscriptionUrl), factory)
         {
             ReconnectTimeout = TimeSpan.FromSeconds(30)
         };
@@ -66,15 +65,25 @@ public async Task Start()
         //Filter General response
         var tt = client.MessageReceived.Select(m => JsonSerializer.Deserialize<WebsocketResponse>(m.ToString()));
 
-        tt.Where(e => e.Type == "ping").Subscribe(msg => SendRequest(new WebsocketRequest("pong")));
+        tt.Where(e => e.Type == WebsocketRequestTypes.PING).Subscribe(msg => SendRequest(new WebsocketRequest(WebsocketRequestTypes.PONG)));
 
         tt.Where(e => !string.IsNullOrEmpty(e?.Id)).Subscribe(r =>
         {
             subscriptionSubject.OnNext(r.Payload?.ToString());
         });
 
         await client.Start();
-        SendRequest(new WebsocketRequest("connection_init"));
+
+        var initRequest = new WebsocketRequest(WebsocketRequestTypes.CONNECTION_INIT);
+        if (_graphClient.WSConnectionInitPayload is not null) 
+        {
+            var initPayload = await _graphClient.WSConnectionInitPayload(_graphClient);
+            if (initPayload is not null)
+            {
+                initRequest.Payload = initPayload;
+            }
+        }
+        SendRequest(initRequest);
 
         var subscriptionRequest = new WebsocketRequest(GetSubscribeCommand())
         {
@@ -87,37 +96,38 @@ public async Task Start()
 
     private string GetSubprotocolString()
     {
-        switch (subscriptionProtocol)
+        switch (_graphClient.SubscriptionProtocol)
         {
             case SubscriptionProtocol.GraphQLWebSocket:
-                return "graphql-transport-ws";
+                return SubscriptionProtocols.GRAPGQL_TRANSPORT_WS;
 
             case SubscriptionProtocol.ApolloWebSocket:
-                return "graphql-ws";
+                return SubscriptionProtocols.GRAPHQL_WS;
 
             default:
-                throw new Exception($"{subscriptionProtocol} is unknown");
+                throw new Exception($"{_graphClient.SubscriptionProtocol} is unknown");
         }
     }
 
     private string GetSubscribeCommand()
     {
-        switch (subscriptionProtocol)
+        switch (_graphClient.SubscriptionProtocol)
         {
             case SubscriptionProtocol.GraphQLWebSocket:
-                return "subscribe";
+                return SubscribeCommands.SUBSCRIBE;
 
             case SubscriptionProtocol.ApolloWebSocket:
-                return "start";
+                return SubscribeCommands.START;
 
             default:
-                throw new Exception($"{subscriptionProtocol} is unknown");
+                throw new Exception($"{_graphClient.SubscriptionProtocol} is unknown");
         }
     }
 
-    private void LogMessage(string message)
+    private static void LogMessage(string message)
     {
-        Console.WriteLine($"{message} - {DateTime.Now.ToString("T")}");
+        // Write logs to debug console
+        Debug.WriteLine($"{message} - {DateTime.Now.ToString("T")}");
     }
 
     private void SendRequest(WebsocketRequest request)

src/Linq2GraphQL.Client.Subscriptions/WebsocketRequest.cs

@@ -13,7 +13,7 @@ public WebsocketRequest(string type)
 
     [JsonPropertyName("type")] public string Type { get; set; }
 
-    [JsonPropertyName("payload")] public GraphQLRequest Payload { get; set; }
+    [JsonPropertyName("payload")] public object Payload { get; set; }
 }
 
 //public class WebsocketRequestPayload

src/Linq2GraphQL.Client.Subscriptions/WebsocketRequestTypes.cs

@@ -0,0 +1,10 @@
+namespace Linq2GraphQL.Client.Subscriptions
+{
+    internal class WebsocketRequestTypes
+    {
+        internal const string PING = "ping";
+        internal const string PONG = "pong";
+        internal const string CONNECTION_INIT = "connection_init";
+
+    }
+}

src/Linq2GraphQL.Client/GraphClient.cs

@@ -36,6 +36,7 @@ public GraphClient(HttpClient httpClient, IOptions<GraphClientOptions> options,
     public HttpClient HttpClient { get; }
     public JsonSerializerOptions SerializerOptions { get; }
 
+    public Func<GraphClient, Task<GraphQLRequest>> WSConnectionInitPayload => options.Value.WSConnectionInitPayload;
     private string GetSubscriptionUrl()
     {
         var baseUrl = HttpClient?.BaseAddress.ToString();

src/Linq2GraphQL.Client/GraphClientOptions.cs

@@ -1,7 +1,9 @@
+
 namespace Linq2GraphQL.Client;
 
 public class GraphClientOptions
 {
     public bool UseSafeMode { get; set; } = false;
     public SubscriptionProtocol SubscriptionProtocol { get; set; } = default;
+    public Func<GraphClient, Task<GraphQLRequest>> WSConnectionInitPayload { get; set; } = opts => null;
 }