Struct HeadLink 

pub struct HeadLink { /* private fields */ }

A <link> for the page’s head that is not an asset of the build: an icon, a canonical URL, a feed. The typed home for what ksx Studio splices before </head>.

Its rel is one or more of a closed list of link types, none of which loads style or script:

Link types	Why they are kept
icon, apple-touch-icon, mask-icon	An image the browser shows for the page, fetched under the policy’s img-src
manifest	The web app manifest; see below
canonical, alternate, author, license	Metadata: the browser fetches and runs nothing
preconnect, dns-prefetch	A connection hint to an origin the page will use: nothing is fetched or run

Everything else is refused, with a code: stylesheet, modulepreload, preload, prefetch, prerender and import load style or script, and a page’s stylesheets and module preloads come from the build’s manifest (HEAD-101); any other word, shortcut included (write icon), is not on the list (HEAD-102). Link types are matched without regard to case and written in lower case. Every value is escaped for its attribute, and a script URL is refused, so a head link is never markup and never runs anything. Add it to a render with RenderCtx::with_head_link; it is written after the route’s stylesheets and preloads, in the order added.

manifest needs a policy the default does not give. The browser fetches a web app manifest under manifest-src, which falls back to the strict policy’s default-src 'none', so the default policy blocks it. PolicyExtensions has no manifest source (it names image and frame sources, a form target and the opener policy), so a page that links a manifest today sees it refused, with a policy violation in the console.

use forma_server::{HeadLink, RenderCtx};

let ctx = RenderCtx::new()
    .with_head_link(HeadLink::new("icon", "/favicon.svg")?.with_type("image/svg+xml"))
    .with_head_link(HeadLink::new("apple-touch-icon", "/apple-touch-icon.png")?);

Verified by: crates/forma-server/tests/internal_renderer/typed_homes.rs > “head_links_are_written_escaped_in_the_head_in_the_order_added” Verified by: crates/forma-server/tests/internal_renderer/typed_homes.rs > “a_head_link_carries_only_the_listed_link_types”

Implementations

impl HeadLink

pub fn new(rel: &str, href: &str) -> Result<HeadLink, HeadLinkError>

A link of type rel (one or more of HeadLink’s link types, separated by whitespace) to href.

Errors

A HeadLinkError with its code:

Code	Cause
HEAD-101	rel names a link type that loads style or script
HEAD-102	rel names no link type, or one outside the list
HEAD-103	href is a javascript: or vbscript: URL, in any case and with any tab, newline or leading control character a browser strips
HEAD-104	href is empty

Verified by: crates/forma-server/tests/internal_renderer/typed_homes.rs > “a_head_link_carries_only_the_listed_link_types” Verified by: crates/forma-server/tests/internal_renderer/typed_homes.rs > “a_head_link_refuses_a_script_url_and_keeps_every_other”

pub fn with_type(self, mime: &str) -> Self

Add a type attribute, such as image/svg+xml.

pub fn with_sizes(self, sizes: &str) -> Self

Add a sizes attribute, such as 180x180.

Trait Implementations

impl Clone for HeadLink

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for HeadLink

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for HeadLink

impl PartialEq for HeadLink

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for HeadLink