Trait Render 

pub trait Render:
    Send
    + Sync
    + 'static {
    type View<'a>: ?Sized;

    // Required methods
    fn template(&self, name: &str) -> Option<TemplateId>;
    fn render(
        &self,
        template: TemplateId,
        view: &Self::View<'_>,
        out: &mut Output<'_>,
    ) -> Result<(), RenderError>;

    // Provided method
    fn error_page(
        &self,
        page: &ErrorPage<'_>,
        out: &mut Output<'_>,
    ) -> Result<bool, RenderError> { ... }
}

A template engine.

The view type is the engine’s: an engine that reads any view through web-net’s View trait (an adapter for a dynamic engine) uses type View = dyn View; an engine that compiles templates against the application’s own types uses that type, and reads it directly.

use web_net::{Output, Render, RenderError, TemplateId, Value, View};

/// Writes the view's `title` field and nothing else.
struct TitleOnly;

impl Render for TitleOnly {
    type View<'a> = dyn View + 'a;
    fn template(&self, name: &str) -> Option<TemplateId> {
        (name == "title").then_some(TemplateId(0))
    }
    fn render(&self, _t: TemplateId, view: &dyn View, out: &mut Output<'_>) -> Result<(), RenderError> {
        let key = view.shape().key("title").ok_or(RenderError::new("demo.no_title"))?;
        match view.get(key) {
            Value::Text(t) => out.write(t.as_bytes()), // a real engine escapes here
            _ => Err(RenderError::new("demo.not_text")),
        }
    }
}

Required Associated Types

type View<'a>: ?Sized

What a handler hands the engine, for any lifetime of the data it borrows: dyn View + 'a for a dynamic engine, the application’s own type (Page, or Page<'a>) for a typed one.

Required Methods

fn template(&self, name: &str) -> Option<TemplateId>

Resolves a template name. Called at build time for every template a route names, so an unknown name stops the application from starting.

fn render( &self, template: TemplateId, view: &Self::View<'_>, out: &mut Output<'_>, ) -> Result<(), RenderError>

Renders template against view into out.

Errors

A RenderError; the request is answered with a 500 error page and the detail goes to the events, never to the visitor.

Provided Methods

fn error_page( &self, page: &ErrorPage<'_>, out: &mut Output<'_>, ) -> Result<bool, RenderError>

Writes the page for a refusal or an error, from the facts web-net shows a visitor. Ok(false) (the default) leaves it to web-net’s built-in page; so does an error, which is not reported further.

Errors

A RenderError; web-net then sends its built-in page.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl Render for NoRender

type View<'a> = dyn View + 'a