Invalid expression term on nullable property

[ghost]

For a reason, I have some string properties on my document type, as these have a Label as their editor. The values of these properties are imported (and should not be editable in Umbraco). I'm using ModelsBuilder but when I define the following on my model, the ModelBuilder fails with the message below.

[IgnorePropertyType("purchasePrice")]
[IgnorePropertyType("resalePrice")]
public partial class ProductVariantContentModel
{
    [ImplementPropertyType("purchasePrice")]
    public decimal? PurchasePrice
    {
        get
        {
            if (this.HasValue("purchasePrice") == false)
                return null;

            var value = this.GetPropertyValue<string>("purchasePrice");
            if (decimal.TryParse(value, NumberStyles.Any, CultureInfo.InvariantCulture, out decimal result))
                return result;

            return null;
        }
    }

    [ImplementPropertyType("resalePrice")]
    public decimal? ResalePrice
    {
        get
        {
            if (this.HasValue("resalePrice") == false)
                return null;

            var value = this.GetPropertyValue<string>("resalePrice");
            if (decimal.TryParse(value, NumberStyles.Any, CultureInfo.InvariantCulture, out decimal result))
                return result;

            return null;
        }
    }
}

This results in the following message:

UmbracoModelsBuilder: UmbracoModelsBuilder failed to generate code: Exception: Response status code does not indicate success (InternalServerError)
{"Message":"An error has occurred.","ExceptionMessage":"Invalid expression term 'decimal'","ExceptionType":"Umbraco.ModelsBuilder.Building.CompilerException","StackTrace":"   at Umbraco.ModelsBuilder.Building.Compiler.ThrowExceptionFromDiagnostic(String path, String code, Diagnostic diagnostic) in D:\\d\\Zbu ModelsBuilder-7\\Umbraco.ModelsBuilder\\Building\\Compiler.cs:line 161\r\n   at Umbraco.ModelsBuilder.Building.Compiler.<>c__DisplayClass12_0.<GetCompilation>b__0(KeyValuePair`2 x) in D:\\d\\Zbu ModelsBuilder-7\\Umbraco.ModelsBuilder\\Building\\Compiler.cs:line 48\r\n   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()\r\n   at System.Linq.Buffer`1..ctor(IEnumerable`1 source)\r\n   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)\r\n   at Umbraco.ModelsBuilder.Building.Compiler.GetCompilation(String assemblyName, IDictionary`2 files, SyntaxTree[]& trees) in D:\\d\\Zbu ModelsBuilder-7\\Umbraco.ModelsBuilder\\Building\\Compiler.cs:line 46\r\n   at Umbraco.ModelsBuilder.Building.CodeParser.Parse(IDictionary`2 files, IEnumerable`1 references) in D:\\d\\Zbu ModelsBuilder-7\\Umbraco.ModelsBuilder\\Building\\CodeParser.cs:line 38\r\n   at Umbraco.ModelsBuilder.Api.ApiHelper.GetModels(String modelsNamespace, IDictionary`2 files) in D:\\d\\Zbu ModelsBuilder-7\\Umbraco.ModelsBuilder\\Api\\ApiHelper.cs:line 16\r\n   at Umbraco.ModelsBuilder.Api.ModelsBuilderApiController.GetModels(GetModelsData data) in D:\\d\\Zbu ModelsBuilder-7\\Umbraco.ModelsBuilder.Api\\ModelsBuilderApiController.cs:line 65\r\n   at lambda_method(Closure , Object , Object[] )\r\n   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance, Object[] methodParameters)\r\n   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary`2 arguments, CancellationToken cancellationToken)\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__0.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Filters.ActionFilterAttribute.<CallOnActionExecutedAsync>d__5.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n   at System.Web.Http.Filters.ActionFilterAttribute.<CallOnActionExecutedAsync>d__5.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Filters.ActionFilterAttribute.<ExecuteActionFilterAsyncCore>d__0.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Filters.AuthorizationFilterAttribute.<ExecuteAuthorizationFilterAsyncCore>d__2.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()"}
UmbracoModelsBuilder:    at Umbraco.ModelsBuilder.Api.ApiClient.EnsureSuccess(HttpResponseMessage result)
   at Umbraco.ModelsBuilder.Api.ApiClient.GetModels(Dictionary`2 ourFiles, String modelsNamespace)
   at Umbraco.ModelsBuilder.CustomTool.CustomTool.UmbracoModelsBuilder.GenerateRaw(String wszInputFilePath, String wszDefaultNamespace, IntPtr[] rgbOutputFileContents, UInt32& pcbOutput, String& errMsg)

Commenting out the properties resolves the issue, and having them as nullable too. But that's not really an option...

[zpqrtbnk]

going to guess here... what happens if you replace the lines

if (decimal.TryParse(value, NumberStyles.Any, CultureInfo.InvariantCulture, out decimal result))
  return result;

with

decimal result;
if (decimal.TryParse(value, NumberStyles.Any, CultureInfo.InvariantCulture, out result))
  return result;

?

The error we're seeing is, we fail to parse your code. And yet, your code is valid. But the syntax you used was introduced in C# version I-cannot-remember. In order for your syntax to be supported, you may want to experiment with the Umbraco.ModelsBuilder.LanguageVersion configuration setting (see Install And Configure) and use something like CSharp7.

Does this help?

[ghost]

Yup, that helps! I was under the impression that it was due to the nullable return type, but indeed it was the usage of the so-called Out variables introduced in C# 7.

We have ModelsBuilder 3.0.10 installed but changing the Umbraco.ModelsBuilder.LanguageVersion value to CSharp7 throws an "Invalid language version 'CSharp7'" ConfigurationErrorsException. In what version of ModelsBuilder is support for C# 7 introduced? Or am I missing another setting somewhere?

[ConfigurationErrorsException: Invalid language version "CSharp7".]
   Umbraco.ModelsBuilder.Configuration.Config..ctor() in D:\d\Zbu ModelsBuilder-7\Umbraco.ModelsBuilder\Configuration\Config.cs:126
   Umbraco.ModelsBuilder.Configuration.<>c.<ModelsBuilder>b__1_0() in D:\d\Zbu ModelsBuilder-7\Umbraco.ModelsBuilder\Configuration\UmbracoConfigExtensions.cs:24
   System.Threading.LazyInitializer.EnsureInitializedCore(T& target, Func`1 valueFactory) +21
   Umbraco.ModelsBuilder.Configuration.UmbracoConfigExtensions.ModelsBuilder(UmbracoConfig umbracoConfig) in D:\d\Zbu ModelsBuilder-7\Umbraco.ModelsBuilder\Configuration\UmbracoConfigExtensions.cs:25
   Umbraco.ModelsBuilder.Umbraco.LiveModelsProvider.get_IsEnabled() in D:\d\Zbu ModelsBuilder-7\Umbraco.ModelsBuilder\Umbraco\LiveModelsProvider.cs:26
   Umbraco.ModelsBuilder.Umbraco.LiveModelsProviderModule.Install() in D:\d\Zbu ModelsBuilder-7\Umbraco.ModelsBuilder\Umbraco\LiveModelsProvider.cs:132

[InvalidOperationException: The pre-application start initialization method Install on type Umbraco.ModelsBuilder.Umbraco.LiveModelsProviderModule threw an exception with the following error message: Invalid language version "CSharp7"..]
   System.Web.Compilation.BuildManager.InvokePreStartInitMethodsCore(ICollection`1 methods, Func`1 setHostingEnvironmentCultures) +850
   System.Web.Compilation.BuildManager.InvokePreStartInitMethods(ICollection`1 methods) +162
   System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath, Boolean& isRefAssemblyLoaded) +128
   System.Web.Compilation.BuildManager.ExecutePreAppStart() +170
   System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +820

[HttpException (0x80004005): The pre-application start initialization method Install on type Umbraco.ModelsBuilder.Umbraco.LiveModelsProviderModule threw an exception with the following error message: Invalid language version "CSharp7"..]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +523
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +107
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +688

[zpqrtbnk]

Roslyn as shipped with ModelsBuilder for v7 stops at CSharp6 and does not support C# 7 indeed.

And... there is no plan to change this for v7.

[ghost]

Allright, then this issue can be closed ;-) And I think one should update the documentation on ModelsBuilder with this limitation.