Docs

Metadata and OG images

Compose titles, descriptions, and social preview images.

Proa metadata is resolved from the current route context. Layouts and pages can both provide metadata; the framework precomputes a metadata map from the route specification and exposes helpers for rendering the current route's head tags.

Title-Only Pages

Route::page creates title-only metadata:

Route::page("/pricing", "Pricing", get(pricing))

Use this for simple pages where layout defaults provide the rest.

Custom Metadata

Implement Metadata for full control:

use proa_framework_axum::{
    CascadeOpenGraph, CascadeValue, Metadata, OpenGraphImage,
};

pub struct PricingMeta;

impl Metadata for PricingMeta {
    fn title(&self) -> CascadeValue<&'static str> {
        CascadeValue::Set("Pricing")
    }

    fn description(&self) -> CascadeValue<&'static str> {
        CascadeValue::Set("Plans and deployment options for Proa.")
    }

    fn open_graph(&self) -> CascadeOpenGraph {
        static IMAGES: [OpenGraphImage; 1] = [
            OpenGraphImage::new("https://proa.so/static/og/pricing.png")
                .with_dimensions(1200, 630)
                .with_alt("Proa pricing"),
        ];

        CascadeOpenGraph {
            images: CascadeValue::Set(&IMAGES),
            ..Default::default()
        }
    }
}

static PRICING_META: PricingMeta = PricingMeta;

let route = Route::page_with_metadata("/pricing", get(pricing), &PRICING_META);

Layout Metadata

Layouts implement Metadata as well as Layout, so they can provide defaults:

impl Metadata for AppLayout {
    fn title(&self) -> CascadeValue<&'static str> {
        CascadeValue::Set("%s - Proa")
    }

    fn description(&self) -> CascadeValue<&'static str> {
        CascadeValue::Set("A Proa application.")
    }
}

Use layout metadata for site-wide title templates, default descriptions, and default Open Graph fields.

Rendering Head Tags

Inside a document layout, call the helpers while route context is installed:

use proa_framework_axum::{render_css_link, render_metadata_head};

fn render_head(cx: &mut proa_core::WebContext) {
    render_metadata_head(cx);
    render_css_link(cx);
}

render_metadata_head reads the resolved metadata for the current route. render_css_link reads the CSS asset path from the current IslandManifest.

Clearing Inherited Values

Use CascadeValue::Tombstone to explicitly clear an inherited field. This is useful for pages that should not inherit layout-level Open Graph images.

CascadeOpenGraph {
    images: CascadeValue::Tombstone,
    ..Default::default()
}

Use tombstones deliberately. Most routes should inherit sensible layout defaults.