In a project I'm working on, CoPilot suggested some jinja syntax for handling an optional field (Option<i64>) as:

#[derive(Template)
struct Foo {
    bar: Option<i64>,
}

{{ bar | default(value="No bar", boolean=true) }}

Currently in askama this would require:

{% if let Some(bar) = bar %}
  {{ bar }}
{% else %}
  No bar
{% endif %}

The downside to using the name default here is that the jinja filter is about undefined or false variables, not Option variables. So the semantics are a little different between jinja and askama.

Jinja docs for default:
https://jinja.palletsprojects.com/en/stable/templates/#jinja-filters.default

jinja-filters.default(value: V, default_value: V = '', boolean: bool = False) → V

If the value is undefined it will return the passed default value, otherwise the value of the variable:

{{ my_variable|default('my_variable is not defined') }}

This will output the value of my_variable if the variable was defined, otherwise 'my_variable is not defined'. If you want to use default with variables that evaluate to false you have to set the second parameter to true:

{{ ''|default('the string was empty', true) }}

So I'd suggest either:

1. accept that askama's syntax and features are oriented around Rust's semantics and so use default to interact with Option. I think this makes the most sense.
2. bikeshed a different name rather than default to make it clear that the filter is different from jinja filter with the same name