Pages

The pages module allows the server to generate HTML pages (e.g. error messages or the directory listing) and can be used to render custom pages from a template, using Pebble as a rendering engine. Support for rendering websites in genhttp-kt is minimalistic, so you should not use this for a website project.

Page Rendering

The following example will show you how to use a Pebble template file to generate a web page with dynamic content via genhttp-kt.

import org.genhttp.api.content.io.Resource
import org.genhttp.api.protocol.Request
import org.genhttp.engine.internal.Host

import org.genhttp.modules.functional.*
import org.genhttp.modules.io.*
import org.genhttp.modules.pages.Renderer
import org.genhttp.modules.pages.getPage
import org.genhttp.modules.practices.defaults

suspend fun main() {
    val template = Renderer.from(Resource.fromClasspath("Template.html").build())

    val app = Inline.create()
        .get { request: Request ->
            val data = mapOf("users" to getUsers())

            request.getPage(template.render(data))
        }

    Host.create()
        .handler(app)
        .defaults()
        .development()
        .run()
}

data class User(val id: Int, val name: String)

fun getUsers(): List<User> = listOf(User(1, "Some User"))

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Users</title>
</head>
<body>

<table>
    <tr>
        <th>ID</th>
        <th>Name</th>
    </tr>
    {% for user in users %}
    <tr>
        <td>{{ user.id }}</td>
        <td>{{ user.name | escape }}</td>
    </tr>
    {% endfor %}
</table>

</body>
</html>

The template is read from the classpath (src/main/resources/Template.html) and compiled once; if the resource changes, it is compiled again on the next rendering. The model is a Map<String, Any?>: Pebble reads the properties of the objects in it, such as user.name of a data class, through their getters. As the output is not escaped automatically, apply the escape filter to values that may contain HTML, such as the name of a user.

Server-Styled Pages

Renderer.server is a built-in renderer using the same theme as the server’s own error pages and directory listings, so you can render a simple page without shipping a template of your own:

val app = Inline.create()
    .get { request: Request ->
        val page = Renderer.server.render("Maintenance", "<p>We'll be back shortly.</p>")

        request.getPage(page)
    }

Neither the title nor the content are escaped by the renderer; escaped() escapes a string for HTML if it contains user input (name.escaped()).