Passing a filtered array to each?

[pdaoust]

Hi, I'm working on someone else's code, and the context passed into one template (let's call it a Bar) contains one property foos which is a Vec<Foo>. Each Foo has a property widget which is used to filter in some {{#each}} blocks but not others. It'd be no problem if the template were simply generating content like this: {{#each foos}}{{#if widget}}<p>{{name}}</p>{{/if}}{{/each}}, but in some cases it's used to create a comma-separated list:

{{#each foos}}{{#if widget}}{{name}}{{#unless @last}}, {{/unless}}{{/if}}{{/each}}

As you can see, if the second-to-last foo is a widget, but the last one is not, there'll be a trailing comma, which causes the generated file to be invalid (it's generating JS code).

I'd like to avoid creating a new foos_that_are_widgets field on the context, so I'm wondering if it's possible to either:

• define a foos_that_are_widgets() function in the impl for Bar that returns the filtered vec
• filter foos during or before {{#each}}

[sunng87]

hi @pdaoust, currently it's not possible to use function as data field directly in handlebars-rust. Because internally we transformed all data into serde_json's Value type so we don't call any function of the data structure.

I will suggest you to filter foo before rendering the template

[pdaoust]

Hi, thanks for the response. I ended up creating a filter helper which serves my needs -- takes a value and a filter-predicate-in-a-string, and renders a very tiny template that checks the truthiness of the predicate for each item in the array. I don't know Rust, but I managed to cargo-cult my way past rustc's complaints about ownership and create a working helper!