§Handling form submission

§Defining a form

The play.data package contains several helpers to handle HTTP form data submission and validation. The easiest way to handle a form submission is to define a play.data.Form that wraps an existing class:

public class User {
    public String email;
    public String password;
}

Form<User> userForm = form(User.class);

Note: The underlying binding is done using Spring data binder.

This form can generate a User result value from HashMap<String,String> data:

Map<String,String> anyData = new HashMap();
anyData.put("email", "[email protected]");
anyData.put("password", "secret");

User user = userForm.bind(anyData).get();

If you have a request available in the scope, you can bind directly from the request content:

User user = userForm.bindFromRequest().get();

§Defining constraints

You can define additional constraints that will be checked during the binding phase using JSR-303 (Bean Validation) annotations:

public class User {
    
    @Required
    public String email;
    public String password;
}

Tip: The play.data.validation.Constraints class contains several built-in validation annotations.

You can also define an ad-hoc validation by adding a validate method to your top object:

public class User {
    
    @Required
    public String email;
    public String password;
    
    public String validate() {
        if(authenticate(email,password) == null) {
            return "Invalid email or password";
        }
        return null;
    }
}

§Handling binding failure

Of course if you can define constraints, then you need to be able to handle the binding errors.

if(userForm.hasErrors()) {
    return badRequest(form.render(userForm));
} else {
    User user = userForm.get();
    return ok("Got user " + user);
}

§Filling a form with initial default values

Sometimes you’ll want to fill a form with existing values, typically for editing:

userForm = userForm.fill(new User("[email protected]", "secret"))

Tip: Form objects are immutable - calls to methods like bind() and fill() will return a new object filled with the new data.

§Register a custom DataBinder

In case you want to define a mapping from a custom object to a form field string and vice versa you need to register a new Formatter for this object.
For an object like JodaTime’s LocalTime it could look like this:

Formatters.register(LocalTime.class, new SimpleFormatter<LocalTime>() {

    private Pattern timePattern = Pattern.compile(
        "([012]?\\\\d)(?:[\\\\s:\\\\._\\\\-]+([0-5]\\\\d))?"
    ); 
    
    @Override
    public LocalTime parse(String input, Locale l) throws ParseException {
        Matcher m = timePattern.matcher(input);
        if (!m.find()) throw new ParseException("No valid Input",0);
        int hour = Integer.valueOf(m.group(1));
        int min = m.group(2) == null ? 0 : Integer.valueOf(m.group(2));
        return new LocalTime(hour, min);
    }
    
    @Override
    public String print(LocalTime localTime, Locale l) {
        return localTime.toString("HH:mm");
    }
  
});

Next: Using the form template helpers