The ctx.render() method

This method lets you render an Eta template as a string and send it as HTTP response.

import {eta} from "@cedx/koa-eta";
import Koa from "koa";
import {join} from "node:path";

const app = new Koa;
eta(app, {views: join(import.meta.dirname, "path/to/view/folder")});

app.use(async ctx => {
  const locals = {message: "Hello World!"};
  await ctx.render("view", locals);
});

Note

The content type of the HTTP response will automatically be set to text/html.

This method accepts up to three arguments, the first of which is mandatory. Its signature is as follows:

/**
 * @param view - The view name.
 * @param locals - The data that should be made available in the view.
 * @param options - The rendering options.
 * @returns The rendering result.
 */
render(view: string, locals: object = {}, options: RenderingOptions = {}): Promise<string>;

Rendering options

async: boolean = false

The view templates can use asynchronous expressions (i.e. await statements, or .then() calls). When this happens, you must inform the Eta engine to render the template asynchronously by setting the async option to true.

// The "view.eta" template contains asynchronous statements.
app.use(async ctx => {
  const locals = {message: "Hello World!"};
  await ctx.render("view", locals, {async: true});
});

writeResponse: boolean = true

By default, the method will write the rendering result in the body of the HTTP response, and set the content type as html.

But sometimes you'll want to leave the response body undefined and just get the final result, or use a different content type if your view template is not in HTML format.

You can do this by setting the writeResponse option to false.

// Use a different content type, such as `application/xml` for an XML view.
app.use(async ctx => {
  const locals = {items: ["one", "two", "three"]};
  ctx.body = await ctx.render("view", locals, {writeResponse: false});
  ctx.type = "xml";
});

// Or maybe use the rendering result to send a mail.
app.use(async ctx => {
  const {createTransport} = await import("nodemailer");
  await createTransport("smtp://user:pwd@smtp.example.com").sendMail({
    from: "foo@bar.xyz",
    to: "baz@qux.xyz",
    subject: "Hello World!",
    html: await ctx.render("view", {}, {writeResponse: false})
  });
	
  ctx.body = null; // 204 No Content.
});