Tiny Scala web framework, inspired by Sinatra
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Scalatra is a tiny Scala web framework inspired by Sinatra and originally based on some code I found on an awesome blog post.

Comments, issues, and pull requests are welcome. Please also see the scalatra-user mailing list, or drop in on IRC at #scalatra on irc.freenode.org


package org.scalatra

class ScalatraExample extends ScalatraServlet {

  // send a text/html content type back each time
  before {
    contentType = "text/html"

  // parse matching requests, saving things prefixed with ':' as params
  get("/date/:year/:month/:day") {
      <li>Year: {params("year")}</li>
      <li>Month: {params("month")}</li>
      <li>Day: {params("day")}</li>

  // produce a simple HTML form
  get("/form") {
    <form action='/post' method='POST'>
      Post something: <input name='submission' type='text'/>
      <input type='submit'/>

  // handle POSTs from the form generated above
  post("/post") {
    <h1>You posted: {params("submission")}</h1>

  // respond to '/' with a greeting
  get("/") {
    <h1>Hello world!</h1>

  // send redirect headers
  get("/see_ya") {

  // set a session var
  get("/set/:session_val") {
    session("val") = params("session_val")
    <h1>Session var set</h1>

  // see session var
  get("/see") {
    session("val") match {
      case Some(v:String) => v
      case _ => "No session var set"

  // Actions that return byte arrays render a binary response
  get("/report.pdf") {
    contentType = "application/pdf"
    val pdf = generatePdf()

  notFound {
    "Not found"

Quick Start

  1. Install Java
You'll need Java installed; I have it running with 1.5
  1. Install simple-build-tool
Scalatra uses sbt (0.7 or above), a fantastic tool for building Scala programs.  For instructions, see [the sbt site](http://code.google.com/p/simple-build-tool/wiki/Setup)
  1. Run sbt
In the directory you downloaded Scalatra to, run `sbt`.
sbt will download core dependencies, and Scala itself if it needs to.
  1. Download dependencies
At the sbt prompt, type `update`.  This will download required dependencies.
  1. Try it out
At the sbt prompt, type `jetty-run`.  This will run Scalatra with the example servlet on port 8080.
  1. Navigate to http://localhost:8080
You should see "Hello world."  You can poke around the example code in example/src/main/scala/TemplateExample.scala to see what's going on.

Maven Repository

To make usage of Scalatra as a dependency convenient, Maven hosting is now available courtesy of Sonatype.

Supported Methods

  • before

    Run some block before a request is returned.

  • get(path)

    Respond to a GET request.

    Specify the route to match, with parameters to store prefixed with : like Sinatra. "/match/this/path/and/save/:this" would match that GET request, and provide you with a params("this") in your block.

  • post(path)

    Respond to a POST request.

    Posted variables are available in the params hash.

  • delete(path)

    Respond to a DELETE request.

  • put(path)

    Respond to a PUT request.

  • error

    Run some block when an error is caught. The error is available in the variable caughtThrowable.

  • after

    Run some block after the matching get/post/delete/put block is run.


Session support has recently been added. To see how to use sessions in your Scalatra apps, check out the test servlet, at core/src/test/scala/ScalatraTest.scala

Flash scope

Flash scope is available by mixing in FlashScopeSupport, which provides a mutable map named flash. Values put into flash scope during the current request are stored in the session through the next request and then discarded. This is particularly useful for messages when using the Post/Redirect/Get pattern.

File Upload Support

File uploads are now supported.

File upload dependencies

  • scalatra-fileupload.jar
  • commons-fileupload.jar
  • commons-io.jar


  • Mix in org.scalatra.fileupload.FileUploadSupport.
  • Be sure that your form has an enctype of multipart/form-data
  • Uploaded files will be available in a map of fileParams or fileMultiParams


import org.scalatra.ScalatraServlet
import org.scalatra.fileupload.FileUploadSupport

class MyApp extends ScalatraServlet with FileUploadSupport {
  get("/") {
    <form method="post" enctype="multipart/form-data">
      <input type="file" name="foo" />
      <input type="submit" />

  post("/") {

Scalate Integration

Scalatra has experimental support for integration with Scalate.

Scalate Dependencies

  • scalatra-scalate.jar
  • scalate-core-1.2.jar
  • a slf4j binding; I like logback


  • Mix in ScalateSupport
  • Create template in src/main/webapp
  • Call renderTemplate with a path to the template (relative to webapp) and attributes


import org.scalatra.ScalatraServlet
import org.scalatra.scalate.ScalateSupport

class MyApp extends ScalatraServlet with ScalateSupport {
  get("/") {
    renderTemplate("index.scaml", "content" -> "yada yada yada")

Testing Your Scalatra Applications

Scalatra includes a test framework for writing the unit tests for your Scalatra application. The framework lets you send requests to your app and examine the response. It can be mixed into the test framework of your choosing; integration with ScalaTest and Specs is already provided. ScalatraTests supports HTTP GET/POST tests with or without request parameters and sessions. For more examples, please refer to core/src/test/scala.



  • scalatra-scalatest


Mix in ShouldMatchers or MustMatchers to your taste...

class MyScalatraServletTests extends ScalatraSuite with ShouldMatchers {
  // `MyScalatraServlet` is your app which extends ScalatraServlet
  addServlet(classOf[MyScalatraServlet], "/*")

  test("simple get") {
    get("/path/to/something") {
      status should equal (200)
      body should include ("hi!")



  • scalatra-specs


object MyScalatraServletTests extends ScalatraSpecification {
  addServlet(classOf[MyScalatraServlet], "/*")
  "MyScalatraServlet when using GET" should {
    "/path/to/something should return 'hi!'" in {
      get("/") {
        status mustEqual(200)
        body mustEqual("hi!")

Other test frameworks


  • scalatra-test

Usage guide

Create an instance of org.scalatra.test.ScalatraTests. Be sure to call start() and stop() before and after your test suite.


There is a new authentication middleware in the scentry directory, to be documented soon. See an example at usage example.

To use it from an SBT project, add the following to your project:

val auth = "org.scalatra" %% "scalatra-auth" % "2.0.0-SNAPSHOT"


While Scalatra can be run standalone for testing and meddling, you can also package it up in a .jar for use in other projects. At the sbt prompt, type package. Scalatra's only dependency is a recent version of the servlet API. For more information, see the sbt site

Migrating from Step to Scalatra

Scalatra was renamed from Step to Scalatra to avoid a naming conflict with (an unrelated web framework)[http://sourceforge.net/stepframework]. scalatra-1.2.0 is identical to step-1.2.0 with the following exceptions:

  1. The package has changed from com.thinkminimo.step to org.scalatra.
  2. The Step class has been renamed to ScalatraServlet.
  3. All other Step* classes have been renamed to Scalatra*.