Validation

Validation

Example 1 - displaying validation errors in a template

Here is the controller action;note that we are using annotations for validation

      public static void fun(@Required(message="Name is required") String name,
                       @Required(message="Age is required and should be >= 10") @Min(10) int age) {

          render(name, age);

      }

And here is the template:

  #{extends 'layout1.html' /}
  #{set title:'Testing validation' /}

  #{ifErrors}
  <h1>Oops!</h1>
  #{errors}
     <li>${error}</li>
  #{/errors}
  #{/ifErrors}

  #{else}
    Hello ${name}, your age is ${age}
  #{/else}

Trick for validating forms during a post and redisplaying the form

Read the official doc. It involves using params.flash() and validation.keep(). The first one stores http parameters in the "flash" and the second one makes the errors available in the next request. These are done using cookies.

Built-in validations

Check out official doc for a number of built-in validations.

Validating complex objects

We have a "model" class:

  package models;

  import java.util.*;
  import javax.persistence.*;

  import play.db.jpa.*;

  import play.data.validation.*;

  @Entity
  public class Client extends Model {

       @Required(message="Name is required")
       public String name;

       @Required
       @Min(10)
       public int age;

}

Note that we are annotating the fields with validations.

Now, we have a controller task:

    public static void fun(@Valid Client c) {

       if(validation.hasErrors())
          System.out.println("error in validation");
       render(c);

    }

The @Valid says that all the annotations in Client have to be verified.

Now, we have the template:

  #{extends 'layout1.html' /}
  #{set title:'Testing validation' /}

  #{ifErrors}
  <h1>Oops!</h1>
  #{errors}
     <li>${error}</li>
  #{/errors}
  #{/ifErrors}

  #{else}
    Hello ${c.name}, your age is ${c.age}
  #{/else}