Merge pull request #274 from bjorg/issue_262

Blazor WebAssembly support: added try-catch for unsupported properties

Author: rose-a

README.md

@@ -139,3 +139,9 @@ subscription.Dispose();
 * [GitHub GraphQL API Docs](https://developer.github.com/v4/guides/forming-calls/)
 * [GitHub GraphQL Explorer](https://developer.github.com/v4/explorer/)
 * [GitHub GraphQL Endpoint](https://api.github.com/graphql)
+
+## Blazor WebAssembly Limitations
+
+Blazor WebAssembly differs from other platforms as it does not support all features of other .NET runtime implementations. For instance, the following WebSocket options properties are not supported and will not be set:
+* [ClientCertificates](https://docs.microsoft.com/en-us/dotnet/api/system.net.websockets.clientwebsocketoptions.clientcertificates?view=netcore-3.1#System_Net_WebSockets_ClientWebSocketOptions_ClientCertificates)
+* [UseDefaultCredentials](https://docs.microsoft.com/en-us/dotnet/api/system.net.websockets.clientwebsocketoptions.usedefaultcredentials?view=netcore-3.1)

src/GraphQL.Client/Websocket/GraphQLHttpWebSocket.cs

@@ -407,8 +407,22 @@ public Task InitializeWebSocket()
 #else
                 _clientWebSocket = new ClientWebSocket();
                 _clientWebSocket.Options.AddSubProtocol("graphql-ws");
-                _clientWebSocket.Options.ClientCertificates = ((HttpClientHandler)Options.HttpMessageHandler).ClientCertificates;
-                _clientWebSocket.Options.UseDefaultCredentials = ((HttpClientHandler)Options.HttpMessageHandler).UseDefaultCredentials;
+                try
+                {
+                    _clientWebSocket.Options.ClientCertificates = ((HttpClientHandler)Options.HttpMessageHandler).ClientCertificates;
+                }
+                catch (PlatformNotSupportedException)
+                {
+                    Debug.WriteLine("unable to set Options.ClientCertificates property; platform does not support it");
+                }
+                try
+                {
+                    _clientWebSocket.Options.UseDefaultCredentials = ((HttpClientHandler)Options.HttpMessageHandler).UseDefaultCredentials;
+                }
+                catch (PlatformNotSupportedException)
+                {
+                    Debug.WriteLine("unable to set Options.UseDefaultCredentials property; platform does not support it");
+                }
                 Options.ConfigureWebsocketOptions(_clientWebSocket.Options);
 #endif
                 return _initializeWebSocketTask = ConnectAsync(_internalCancellationToken);