Receiving form params to Ktor server - kotlin

Question

I'm new to Java and Kotlin, trying to build a contact form with Ktor, so I enabled the insecure connection of my gmail from here, and built the app below:
blogApp.kt:
package blog
import org.jetbrains.ktor.netty.*
import org.jetbrains.ktor.routing.*
import org.jetbrains.ktor.application.*
import org.jetbrains.ktor.features.*
import org.jetbrains.ktor.host.*
import org.jetbrains.ktor.http.*
import org.jetbrains.ktor.response.*
import org.apache.commons.mail.*
fun Application.module() {
install(DefaultHeaders)
install(CallLogging)
install(Routing) {
get("/") {
call.respondText("""
My Example Blog2
<form action="/contact-us" method="post">
<input name="subject" placeholder="Subject">
<br>
<textarea name="message" placeholder="Your message ..."></textarea>
<br>
<button>Submit</button>
</form>
""", ContentType.Text.Html)
}
post("/contact-us") {
SimpleEmail().apply {
setHostName("smtp.gmail.com")
setSmtpPort(465)
setAuthenticator(DefaultAuthenticator("my_alias#gmail.com", "my_gmil_passoword"))
setSSLOnConnect(true)
setFrom("my_alias#gmail.com")
setSubject("subject") // I need to use formParam
setMsg("message") // I need to use formParam
addTo("my_alias#gmail.com")
}.send() // will throw email-exception if something is wrong
call.respondRedirect("/contact-us/success")
}
get("/contact-us/success") {
call.respondText("Your message was sent", ContentType.Text.Html)
}
}
}
fun main(args: Array<String>) {
embeddedServer(Netty, 8080, watchPaths = listOf("BlogAppKt"), module = Application::module).start()
}
build.gradle:
group 'Example'
version 'alpha'
buildscript {
ext.kotlin_version = '1.1.4-3'
repositories {
mavenCentral()
}
dependencies {
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
}
}
apply plugin: 'java'
apply plugin: 'kotlin'
sourceCompatibility = 1.8
ext.ktor_version = '0.4.0'
repositories {
mavenCentral()
maven { url "http://dl.bintray.com/kotlin/ktor" }
maven { url "https://dl.bintray.com/kotlin/kotlinx" }
}
dependencies {
compile "org.jetbrains.kotlin:kotlin-stdlib-jre8:$kotlin_version"
compile "org.jetbrains.ktor:ktor-core:$ktor_version"
compile "org.jetbrains.ktor:ktor-netty:$ktor_version"
compile "org.apache.commons:commons-email:1.4"
compile "org.slf4j:slf4j-simple:1.7.25"
compile "ch.qos.logback:logback-classic:1.2.1"
testCompile group: 'junit', name: 'junit', version: '4.12'
}
compileKotlin {
kotlinOptions.jvmTarget = "1.8"
}
compileTestKotlin {
kotlinOptions.jvmTarget = "1.8"
}
kotlin {
experimental {
coroutines "enable"
}
}
jar {
baseName 'abc'
manifest {
attributes 'Main-Class': 'blog.BlogAppKt'
}
from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
}
and things gone smoothly with it, I was able to send an email to myself then redirect to the success page, but the message got sent is with pre-set data:
setSubject("subject") // I need to use formParam
setMsg("message") // I need to use formParam
how can I make the Ktor receive the data the user really entered in the form, how can I read the form params?

Answer 1

You can use call.receive<ValuesMap>() and introspect the data:
import org.jetbrains.ktor.request.* // for recieve
import org.jetbrains.ktor.util.* // for ValuesMap
post("/contact-us") {
val post = call.receive<ValuesMap>()
val subj = post["subject"]
val msg = post["message"]
SimpleEmail().apply { ... }
}
NOTE: ValuesMap is deprecated in latest ktor version, so use the following code:
val post = call.receiveParameters()

Answer 2

Well although the above answer would have been correct at that point of time, today when I am going through kotlin + Ktor, I see that the above answer is not valid anymore.
What you need now is something like this:
call.receive< Parameters >()["PARAM_NAME"]
Parameters class is in the following package: io.ktor.http.Parameters
Nikhil