feat: Add primitive handling to CompiledQuery result writer

src/Http/Wolverine.Http.Marten/CompiledQueryWriterPolicy.cs

@@ -2,6 +2,7 @@
 using JasperFx.CodeGeneration.Frames;
 using JasperFx.CodeGeneration.Model;
 using JasperFx.Core.Reflection;
+using Marten;
 using Marten.Linq;
 using Wolverine.Http.Resources;
 using QueryableExtensions = Marten.AspNetCore.QueryableExtensions;
@@ -31,17 +32,51 @@ public bool TryApply(HttpChain chain)
         if (compiledQueryClosure is null) return false;
 
         var arguments = compiledQueryClosure.GetGenericArguments();
+
+        // If we're dealing with a primitive return type we need to write its string representation directly
+        if (arguments[1].IsPrimitive)
+        {
+            // This call runs the query
+            var queryCall =
+                typeof(MartenQueryMethodCall<,>).CloseAndBuildAs<MethodCall>(result, arguments);
+            chain.Postprocessors.Add(queryCall);
 
-        var methodCall = typeof(MartenWriteArrayMethodCall<,>).CloseAndBuildAs<MethodCall>(result, (_responseType, _successStatusCode), arguments);
+            // This call writes the response directly to the HttpContext as a string
+            var writeStringCall = MethodCall.For<HttpHandler>(handler => HttpHandler.WriteString(null!, ""));
+            writeStringCall.Arguments[1] = new Variable(queryCall.ReturnVariable!.VariableType,
+                $"{queryCall.ReturnVariable.Usage}.ToString()", queryCall);
+            chain.Postprocessors.Add(writeStringCall);
+        }
+        else
+        {
+
+            var writeJsonCall =
+                typeof(MartenWriteJsonToStreamMethodCall<,>).CloseAndBuildAs<MethodCall>(result,
+                    (_responseType, _successStatusCode), arguments);
+            chain.Postprocessors.Add(writeJsonCall);
+        }
 
-        chain.Postprocessors.Add(methodCall);
         return true;
     }
 }
 
-public class MartenWriteArrayMethodCall<TDoc, TOut> : MethodCall
+public class MartenQueryMethodCall<TDoc, TOut> : MethodCall
+{
+    public MartenQueryMethodCall(Variable resultVariable) : base(typeof(IDocumentSession), FindMethod())
+    {
+        Arguments[0] = resultVariable;
+    }
+
+    static MethodInfo FindMethod()
+    {
+        return ReflectionHelper.GetMethod<IDocumentSession>(x =>
+            x.QueryAsync((ICompiledQuery<TDoc, TOut>)null!, default))!;
+    }
+}
+
+public class MartenWriteJsonToStreamMethodCall<TDoc, TOut> : MethodCall
 {
-    public MartenWriteArrayMethodCall(Variable resultVariable, (string responseType, int successStatusCode) options) : base(typeof(QueryableExtensions), FindMethod(resultVariable))
+    public MartenWriteJsonToStreamMethodCall(Variable resultVariable, (string responseType, int successStatusCode) options) : base(typeof(QueryableExtensions), FindMethod(resultVariable))
     {
         Arguments[1] = resultVariable;
         Arguments[3] = Constant.ForString(options.responseType);

src/Http/Wolverine.Http.Tests/Marten/compiled_query_writer.cs

@@ -43,6 +43,28 @@ public async Task endpoint_returning_compiled_list_query_should_return_query_res
         approvedInvoiceList.ShouldNotBeNull();
         approvedInvoiceList.Count.ShouldBe(approvedInvoices);
     }
+
+    [Fact]
+    public async Task endpoint_returning_compiled_primitive_query_should_return_query_result()
+    {
+        await using var session = Store.LightweightSession();
+        int invoicesCount = 5;
+        for (int i = 0; i < invoicesCount; i++)
+        {
+            var invoice =
+                new Invoice()
+                {
+                };
+            session.Store(invoice);
+        }
+
+        await session.SaveChangesAsync();
+
+        var approvedInvoiceList = await Host.GetAsText("/invoices/compiled/count");
+        approvedInvoiceList.ShouldNotBeNull();
+        int.TryParse(approvedInvoiceList, out var result).ShouldBeTrue();
+        result.ShouldBe(invoicesCount);
+    }
 
     [Fact]
     public async Task endpoint_returning_compiled_query_should_return_query_result()

src/Http/WolverineWebApi/Internal/Generated/WolverineHandlers/GET_invoices_compiled_count.cs

@@ -0,0 +1,47 @@
+// <auto-generated/>
+#pragma warning disable
+using Microsoft.AspNetCore.Routing;
+using System;
+using System.Linq;
+using Wolverine.Http;
+using Wolverine.Marten.Publishing;
+using Wolverine.Runtime;
+
+namespace Internal.Generated.WolverineHandlers
+{
+    // START: GET_invoices_compiled_count
+    public class GET_invoices_compiled_count : Wolverine.Http.HttpHandler
+    {
+        private readonly Wolverine.Http.WolverineHttpOptions _wolverineHttpOptions;
+        private readonly Wolverine.Runtime.IWolverineRuntime _wolverineRuntime;
+        private readonly Wolverine.Marten.Publishing.OutboxedSessionFactory _outboxedSessionFactory;
+
+        public GET_invoices_compiled_count(Wolverine.Http.WolverineHttpOptions wolverineHttpOptions, Wolverine.Runtime.IWolverineRuntime wolverineRuntime, Wolverine.Marten.Publishing.OutboxedSessionFactory outboxedSessionFactory) : base(wolverineHttpOptions)
+        {
+            _wolverineHttpOptions = wolverineHttpOptions;
+            _wolverineRuntime = wolverineRuntime;
+            _outboxedSessionFactory = outboxedSessionFactory;
+        }
+
+
+
+        public override async System.Threading.Tasks.Task Handle(Microsoft.AspNetCore.Http.HttpContext httpContext)
+        {
+            var messageContext = new Wolverine.Runtime.MessageContext(_wolverineRuntime);
+            // Building the Marten session
+            await using var documentSession = _outboxedSessionFactory.OpenSession(messageContext);
+
+            // The actual HTTP request handler execution
+            var compiledCountQuery = WolverineWebApi.Marten.InvoicesEndpoint.GetCompiledCount();
+
+            var result_of_QueryAsync = await documentSession.QueryAsync<WolverineWebApi.Marten.Invoice, int>(compiledCountQuery, httpContext.RequestAborted).ConfigureAwait(false);
+            await Wolverine.Http.HttpHandler.WriteString(httpContext, result_of_QueryAsync.ToString()).ConfigureAwait(false);
+        }
+
+    }
+
+    // END: GET_invoices_compiled_count
+
+
+}
+

src/Http/WolverineWebApi/Marten/Documents.cs

@@ -70,6 +70,12 @@ public static ByIdCompiled GetCompiled(Guid id)
     {
         return new ByIdCompiled(id);
     } 
+
+    [WolverineGet("/invoices/compiled/count")]
+    public static CompiledCountQuery GetCompiledCount()
+    {
+        return new CompiledCountQuery();
+    } 
 }
 
 public class Invoice
@@ -104,4 +110,12 @@ public ByIdCompiled(Guid id)
     {
         return q => q.FirstOrDefault(x => x.Id == Id);
     }
-}
+}
+
+public class CompiledCountQuery : ICompiledQuery<Invoice, int>
+{
+    public Expression<Func<IMartenQueryable<Invoice>, int>> QueryIs()
+    {
+        return q => q.Count();
+    }
+}