How to treat 0 as truthy

[sellomkantjwa]

I tried using

testing Var: 
{{#if var includeZero=true}}
 var is set to {{var}}
{{/if}}

but I get

Unhandled Exception: System.InvalidOperationException: Sequence contains more than one element
 at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source)
 at HandlebarsDotNet.Compiler.ConditionalBlockAccumulatorContext..ctor(Expression startingNode)
 at HandlebarsDotNet.Compiler.BlockAccumulatorContext.Create(Expression item, HandlebarsConfiguration configuration)
 at HandlebarsDotNet.Compiler.BlockAccumulator.ConvertTokens(IEnumerable`1 sequence)+MoveNext()
 at System.Collections.Generic.List`1.AddEnumerable(IEnumerable`1 enumerable)
 at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
 at HandlebarsDotNet.Compiler.ExpressionBuilder.ConvertTokensToExpressions(IEnumerable`1 tokens)
 at HandlebarsDotNet.Compiler.HandlebarsCompiler.Compile(TextReader source)
 at HandlebarsDotNet.Handlebars.HandlebarsEnvironment.Compile(String template)

[rexm]

Handlebars doesn’t support arbitrary statements.

You could try an inverted #if helper like #not to test the value of var negatively.

[sellomkantjwa]

Cool thanks,
Turns out this syntax applies to the JS parser:
handlebars-lang/handlebars.js#608

[tyriker]

@rexm do you mean includeZero=true as being an arbitrary statement? The includeZero option has been a part of the #if helper since roughly 2014. https://handlebarsjs.com/guide/builtin-helpers.html#if

Should Handlebars.NET support this option? I expected it to work and saw the same result.

I believe the exception comes from here

Handlebars.Net/source/Handlebars/Compiler/Lexer/Converter/BlockAccumulators/ConditionalBlockAccumulatorContext.cs

Line 33 in 9cf1672

var argument = HandlebarsExpression.Boolish(helperExpression.Arguments.Single());

-- which is just the reason for the Exception, not the underlying problem/solution.

I have forked the repo to take a closer look, but can't promise anything and may opt for a workaround as it relates to my current needs.

[rexm]

I think I misunderstood what was originally being asked. I don’t think it would be terribly hard to extend the parser to handle this grammar.