Validator Quickstart

To learn about validator features, let's look at a complete example of validating a form and displaying the error messages. I assume in this tutorial that your web framework is Spark but you can use what ever you want just read this page.

Defining context

Okay so we have a form to validate the inscription of an user. The fields are :

• Last ame
• First name
• Website (optional)
• Email
• Password
• Password confirmation

Let's code

First we need to defining the route :

post("/user/signin_validation", UserController::signup);

Next let's define UserController.signin() :

public static Object signup(Request req, Response res) {
    // Todo signup new user or throw error
}

Now need to instantiate a new Form to handle inputs from user :

public static Object signup(Request req, Response res) {
    SparkForm sp = new SparkForm(req);
}

For those who are wondering where the SparkForm comes from, this is a proposal to implement the Form class so that the Validator class can know where the information comes from or you need to create or find a class that implements Form and implement the behaviors of the interface.

Now we need to instantiate the Validator :

public static Object signup(Request req, Response res) {
    SparkForm sp = new SparkForm(req);
    Validator va = new Validator(sp);
}

By default language of error's message are in english. Consult this page page to know how to implement a language.

So now that we have our validator, we just need to add the rules that the user must follow. If one of the rules fails an error will return :

public static Object signup(Request req, Response res) {
    SparkForm sp = new SparkForm(req);
    Validator va = new Validator(sp);
    try { 
        va
            .addRule("lastname, firstname -> min_length: 3 | max_length: 25 | not_empty")
            .addRule("website             -> optional | url")
            .addRule("email               -> email | unique: users, email")
            .addRule("password            -> min_length: 5 | confirm");
    } catch (RuleParseException ex) {
        e.printStackTrace();
    }
}

And finally we need to check if the new user can be added to the database or if we need to return an error message :

public static Object signup(Request req, Response res) {    
    SparkForm sp = new SparkForm(req);
    Validator va = new Validator(sp);
    try { 
        va
            .addRule("lastname, firstname -> min_length: 3 | max_length: 25 | not_empty")
            .addRule("email               -> email | unique: users, email")
            .addRule("password            -> min_length: 5 | confirm");
    } catch (RuleParseException ex) {
        e.printStackTrace();
    }
    Map<String, String> check = va.check();
    if (check.isEmpty()) {
        // add user to the database
        return new JSONObject().put("success", true).toString();
    }
    else 
        return new Gson().toJson(check);
}

And that's it ! Now you can focus on only what the website do and not how can i handle this fu**** form... :D