Question

I’ve got to say I’m a little confused about how to handle request parameter using the new Play Framework 2. The data comes from different origins regarding how the request is made. So far, here’s the possibilities :

1 – If you do a simple GET :

ctx().request().queryString()

2 – If you do a POST using an HTML Form :

The form :

<form method="post" action="/">
    <input type="hidden" name="foo" value="bar" />
    <input type="hidden" name="t" value="1" />
    <input type="hidden" name="bool" value="true" />
    <input type="submit" name="submit" value="Submit" />
</form>

The method :

public static Result test() {
    ctx().request().queryString();             // {} ; As expected
    ctx().request().body();                    // contains data
    ctx().request().body().asFormUrlEncoded(); // contains data
    ctx().request().body().asJson();           // empty
    return ok();
}

This seems normal.

Now if I add @BodyParser.Of(BodyParser.Json.class) (suppose I accept both Ajax POST and normal POST for fallback in Non-JS case) :

@BodyParser.Of(BodyParser.Json.class)
public static Result test() {
    ctx().request().queryString();             // {} ; as Expected
    ctx().request().body();                    // contains data
    ctx().request().body().asFormUrlEncoded(); // empty : Shouldn't this contains data since I posted them via a simple form ?!
    ctx().request().body().asJson();           // empty
    return ok();
}

And then, the hell hapened : How can I get the values of a simple form if none of them are filled (asJson, asFormUrlEncoded, etc) ?!

3 – If you do a POST via AJAX :

// Code in JS used :
$.ajax({
    'url': '/',
    'dataType': 'json',
    'type': 'POST',
    'data': {'foo': 'bar', 't': 1, 'bool': true}
});

Result :

public static Result test() {
    ctx().request().queryString();             // {}
    ctx().request().body();                    // contains data
    ctx().request().body().asFormUrlEncoded(); // contains data
    ctx().request().body().asJson();           // empty
    return ok();
}

With the @BodyParser.Of(BodyParser.Json.class) :

@BodyParser.Of(BodyParser.Json.class)
public static Result test() {
    ctx().request().queryString();             // {}
    ctx().request().body();                    // contains data
    ctx().request().body().asFormUrlEncoded(); // empty
    ctx().request().body().asJson();           // empty : Shouldn't this contains data since I espect JSON ?!
    return ok();
}

Here the inconsistencies is the asJson() method that should return the data since, according to the doc

Note: This way, a 400 HTTP response will be automatically returned for non JSON requests. (http://www.playframework.org/documentation/2.0/JavaJsonRequests)

What I’d like to know is what is the best decorator+method for a POST that would accept a simple post from HTML or an Ajax Request with POST?

Answer 1

I would recommend to use the Form classes provided by PlayFramework.
The Form will bind its values to the provided request data.

There are two different Form implementations:

1. DynamicForm: POST data is available through Map accessors methods

2. Form: the generic form of Form will map the POST data to an instance of an entity class [more information]

   The form also provides some usefull features like automatic type conversion, validation, error reporting and so on.

a simple example with a dynamic form:

ajax request:

$.post("@routes.Application.movetodo()", 
    { "id": 123, "destination": destination }, function(data)
        {
           // do something when request was successfull
        });

Routes file:

GET     /                           controllers.Application.index()
POST    /movetodo                   controllers.Application.movetodo()

Controller implementation:

public static Result movetodo()
{
    DynamicForm data = form().bindFromRequest(); // will read each parameter from post and provide their values through map accessor methods
    // accessing a not defined parameter will result in null
    String id = data.get("id");
    String destination = data.get("destination");

    return ok();
}