Helper not registered first time

[joamla96]

I've implemented a fairly simple helper to handle if conditions.
For some reason, when i run the code first time, it ends up throwing an exception that this specific helper is not registered. If I hit the endpoint again, it works perfectly fine and continues to work fine until I restart the application, where it will then throw the exception again the first time.

Don't think it'll help, but cant hurt, the exception it throws:

HandlebarsDotNet.HandlebarsRuntimeException: Template references a helper that is not registered. Could not find helper 'ifCond'
   at HandlebarsDotNet.Compiler.HelperFunctionBinder.LateBindHelperExpression(BindingContext context, String helperName, IEnumerable`1 arguments)
   at lambda_method(Closure , TextWriter , Object )
   at HandlebarsDotNet.Compiler.DeferredSectionVisitor.RenderSection(Object value, BindingContext context, Action`2 body, Action`2 inversion)
   at lambda_method(Closure , TextWriter , Object )
   at HandlebarsDotNet.Handlebars.HandlebarsEnvironment.<>c__DisplayClass7_0.<Compile>b__0(Object context)
   at FileGeneratorService.Service.GeneratePDF(VM_Quote quote) in D:\Users\jola\Source\Repos\Utility Portal\FileGeneratorService\Service.cs:line 224
   at WebAPI.Controllers.QuotesController.GetExport(Int32 id, String type) in D:\Users\jola\Source\Repos\Utility Portal\WebAPI\Controllers\QuotesController.cs:line 293
   at Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.TaskOfIActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at System.Threading.Tasks.ValueTask`1.get_Result()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeActionMethodAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeNextActionFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.InvokeInnerFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware.Invoke(HttpContext httpContext)
   at WebAPI.MiddlewareDeveloperException.Invoke(HttpContext context) in D:\Users\jola\Source\Repos\Utility Portal\WebAPI\MiddlewareDeveloperException.cs:line 23

and the helper itself:

Handlebars.RegisterHelper("ifCond", (writer, options, context, arguments) =>
{
	if (arguments[0] == null || arguments[1] == null)
	{
		options.Inverse(writer, (object)context);
		return;
	}

	if (arguments[0].ToString() == arguments[1].ToString())
	{
		options.Template(writer, (object)context);
	} else {
		options.Inverse(writer, (object)context);
	}
});

[rexm]

Can you please also share the template and the code where it is being compiled and invoked?

[joamla96]

A template where its being used looks like this:

		<!-- Spacing Element, because floats are weird -->
		<div style="clear: both; padding-top: 15px;">&nbsp;</div>

        {{Quote.FreeText}}

		{{#productGroups}}
		{{ifCond Category.SystemType 'eq' 'iaas'}}
		{{> ProductGroupsIaas}}
		{{else}}
		{{> ProductGroups}}
		{{/ifCond}}
		{{/productGroups}}

		<br /><br />

		<table>
			<thead>

and the invocation is set up like this:

var bodyTask = File.ReadAllTextAsync(path + "/Body.html");
var headerTask = File.ReadAllTextAsync(path + "/Header.html");
var footerTask = File.ReadAllTextAsync(path + "/Footer.html");

var bodyTemplate = Handlebars.Compile(await bodyTask);
var headerTemplate = Handlebars.Compile(await headerTask);
var footerTemplate = Handlebars.Compile(await footerTask);

Handlebars.RegisterHelper("ifCond", (writer, options, context, arguments) =>
            {
                if (arguments[0] == null || arguments[1] == null || arguments[2] == null)
                {
                    options.Inverse(writer, (object)context);
                    return;
                }

                var passed = false;

                switch (arguments[1])
                {
                    case "eq":
                        if (arguments[0].ToString() == arguments[2].ToString()) passed = true;
                        break;

                    case "grt":
                        if (decimal.Parse(arguments[0].ToString()) > decimal.Parse(arguments[2].ToString())) passed = true;
                        break;
                }


                if (passed)
                {
                    options.Template(writer, (object)context);
                }
                else
                {
                    options.Inverse(writer, (object)context);
                }
            });
var data = new BodyData();
data.Quote = quote;

var dataHF = new DataHeaderFooter();
dataHF.Quote = quote;
dataHF.LogoPath = this.config["LogoPath"];

var bodyHtml = bodyTemplate(data);
var headerHtml = headerTemplate(dataHF);
var footerHtml = footerTemplate(dataHF);

var render = new HtmlToPdf();

var header = new HtmlHeaderFooter() { HtmlFragment = headerHtml, LoadStylesAndCSSFromMainHtmlDocument = true, Height = 30, DrawDividerLine = false };
var footer = new HtmlHeaderFooter() { HtmlFragment = footerHtml, LoadStylesAndCSSFromMainHtmlDocument = true };

render.PrintOptions.MarginTop = header.Height;
render.PrintOptions.MarginBottom = footer.Height;
render.PrintOptions.MarginLeft = 0;
render.PrintOptions.MarginRight = 0;

var result = render
	.RenderHtmlAsPdf(bodyHtml)
	.AddHTMLHeaders(header)
	.AddHTMLFooters(footer);

return result.Stream;

Sorry for the late reply, it got drowned in my feed :D

[artemutin]

I had kind of similar issue, and I was able to fix it by moving helper registration before compilation of any templates