Question

Using play framework 2.0 in Java mode and I want to pass a list of strings to a Controller using the URL parameters.

Given a URL such as:

http://localhost:9000/echo?messages=hello&messages=world

I want to call my Controller method:

public static Result echo(List<String> messages){
    return ok("Size: " + messages.size());
}

My routes file looks like this:

GET      /echo             controllers.Application.echo(messages: List[String])

But it doesn’t work. I get errors claiming there is no QueryString binder for List[String]. This doesn’t seem right to me as this was pretty standard functionality in the previous version. Does anybody know how I can pass a list of strings to the controller using a Java project?

Answer 1

For now you can retrieve them from the query string:

public static Result echo(){
    String[] messages = request().queryString().get("messages");
    return ok("Size: " + messages.length);
}

Update: A list binder has been added, so you can just write the following:

public static Result echo(List<String> messages) {
  return ok("Size:" + messages.size());
}

Be sure your route definition looks like the following:

GET   /echo      controllers.Application.echo(messages: java.util.List[String])