How to pass partial as an argument to the helper function?

[Bipinoli]

How can I pass the partial defined in the template as a function argument to a helper function?

For example say I have a helper function "greeter". I want to do something like this.

{{#*inline "my_partial"}}{{#each something}}({{this}}){{/each}}{{/inline}}
{{greeter {{>my_partial}}}}

[YannikSc]

Hey, this is not a builtin functionality in Handlebars as far as I know, but to work around that you could create a custom helper which renders the partial and pass the result of that helper to your helper, like so:

// Register this as `.register_helper("eval", Box::new(EvaluatePartialHelper))`
struct EvaluatePartialHelper;

impl handlebars::HelperDef for EvaluatePartialHelper {
    fn call_inner<'reg: 'rc, 'rc>(
        &self,
        h: &handlebars::Helper<'rc>,
        reg: &'reg Handlebars<'reg>,
        ctx: &'rc handlebars::Context,
        rc: &mut handlebars::RenderContext<'reg, 'rc>,
    ) -> Result<handlebars::ScopedJson<'rc>, handlebars::RenderError> {
        let Some(name) = h.param(0) else {
            return Err(handlebars::RenderErrorReason::MissingVariable(
                "partial name".to_string().into(),
            )
            .into());
        };

        let partial_name = name
            .value()
            .as_str()
            .ok_or(RenderErrorReason::InvalidParamType("String"))?;
        let mut str_out = StringOutput::new();
        rc.get_partial(partial_name)
            .ok_or_else(|| RenderErrorReason::PartialNotFound(partial_name.to_string()))?
            .render(reg, ctx, rc, &mut str_out)?;

        Ok(handlebars::ScopedJson::Derived(Value::String(
            str_out.into_string()?,
        )))
    }
}

{{#*inline "my_partial"}}
Something that is renderered in this partial.
It can use {{variables}} and {{helpers variables}}.
{{/inline}}

{{greeter (eval "my_partial")}}

Everything that happens in the partial will still affect and use the main template context as it would when it is rendered in a normal {{>my_partial}} include.