Use a templating engine

Example showing how to use the Templating modules - in this case Handlebars, both by standard response manipulation and via a typesafe view lens.

Gradle setup

dependencies {
    implementation(platform("org.http4k:http4k-bom:5.16.2.0"))
    implementation("org.http4k:http4k-core")
    implementation("org.http4k:http4k-template-handlebars")
}

Code

package guide.howto.use_a_templating_engine

import org.http4k.core.Body
import org.http4k.core.ContentType.Companion.TEXT_HTML
import org.http4k.core.HttpHandler
import org.http4k.core.Method.GET
import org.http4k.core.Request
import org.http4k.core.Response
import org.http4k.core.Status.Companion.OK
import org.http4k.core.with
import org.http4k.template.HandlebarsTemplates
import org.http4k.template.ViewModel
import org.http4k.template.viewModel

// this view has the default template path of: guide/howto/using_templates/Person.hbs,
// although that is overridable by setting the template property from ViewModel
data class Person(val name: String, val age: Int) : ViewModel

fun main() {

    val renderer = HandlebarsTemplates().HotReload("src/docs")

    val view = Body.viewModel(renderer, TEXT_HTML).toLens()

    val app: HttpHandler = {
        val viewModel = Person("Bob", 45)
        Response(OK).body(renderer(viewModel))
        // OR:
        Response(OK).with(view of viewModel)
    }

    println(app(Request(GET, "/someUrl")))
}