Simple Ktor ThymeLeaf server on Android doesn't render page while using ThymeLeaf variable pr-CodePudding

I was trying to create simple Android application using ktor as server on the device.

I have managed to add dependecies for ktor 1.6.8 in my android project and I have tried to follow the docs I have managed to host and render very basic html page, but when trying to use model data property with thymeleaf I encounter some strange problem - the page is not rendered at all.

I.E:

<html xmlns:th="http://www.thymeleaf.org">
<body>
<h1 th:text="'Hello, '   ${user}"></h1>
</body>
</html>

This renders Hello, ThymeleafUser(id=1, name=Scott) but changing to:

<html xmlns:th="http://www.thymeleaf.org">
<body>
<h1 th:text="'Hello, '   ${user.name}"></h1>
</body>
</html>

Doesn't render page at all (instead rendering expectedHello, Scott)

The code for Server is more or less something taken from ktor generator and I have putted it into single kotlin class:

package com.example.testapp

import io.ktor.application.*
import io.ktor.response.*
import io.ktor.routing.*
import io.ktor.server.engine.*
import io.ktor.server.netty.*
import io.ktor.thymeleaf.*
import org.thymeleaf.templateresolver.ClassLoaderTemplateResolver
import kotlin.concurrent.thread

class Server {
    companion object {
        fun startServer(){
            thread(start=true) {
                embeddedServer(Netty, host = "0.0.0.0", port = 12345) {
                    install(Thymeleaf){
                        setTemplateResolver(ClassLoaderTemplateResolver().apply {
                            prefix = "templates/"
                            suffix = ".html"
                            characterEncoding = "utf-8"
                        })
                    }
                    routing {
                        get("/html-thymeleaf") {
                            val sampleUser = ThymeleafUser(1, "Scott")
                            call.respond(ThymeleafContent("index", mapOf("user" to sampleUser)))
                        }

                    }
                }.start(wait = true)
            }
        }
    }
}
data class ThymeleafUser(val id: Int, val name: String)

The Server.startServer() is called in Andorid MainActivity onCreate method.

My question is: Why is this behavior occuring? Why I cannot access to property of the "user" as shown in examples or on github.

Perhaps this is just a noob question, but I don't see any logs, any stack trace, nothing to direct me how to solve this.

CodePudding user response：

Unfortunately, to evaluate expressions like ${user.name}, Thymeleaf uses classes from the java.beans package which aren't available on Android. In the Logcat I see the Unresolved exception class when finding catch block: java.beans.IntrospectionException.