The implementation of a very simplistic form development will consist of two actions (the names are fictitious and used just as an example):

• A "show" action, to display the form
• A "save" action, which deals with the form data (after a submit) and displays the result

But in most cases, to respond properly to errors, in order to prevent the use of buttons "refresh" browsers which then execute same processing on forms datas ("save" action), etc. ..., it is better to have such action list:

• A "prepare" action that prepares data for a new form (in session initialization for example, with reading of the original data in a database, for example) and redirects to "show"
• A "show" action that displays the form with data sessions, and displays any data entry errors.
• A "save" action which verifies the data entered. If there are errors, saves them in session and redirects to "show", or save the data (in a database for example) and redirects to "end"
• An "end" action, which cleans data in session, and displays a confirmation page, or redirects to another action whatsoever ...

You generally use a template in which you put your html tags forms. For example:

  <form action="index.php/monmodule/default/save" method="POST">
  <fieldset> <legend>Indicate your identity</legend>
     <table>
      <tr>
        <td><label for="name-field">Your name</label></td>
        <td><input type="text" name="name" id="name-field" /></td>
      </tr>
      <tr>
        <td><label for="surname-field">Your surname</label></td>
        <td><input type="text" name="surname" id="surname-field" /></td>
      </tr>
      </table>
  </fieldset>
  <p><input type="submit" value="Ok" />
  </form>

Of course you can add javascript to check the data entered by the user and use all types of HTML fields.

However, the example is not entirely correct, because the url is written entirely in the form. This is problematic when you change for example the url in the configuration, or when you want to reuse the module in other projects.

It is therefore preferable to use the template plugins formurl and formurlparam, to which you specify the selector and parameters of the action which will process the form datas after the submission. The first is used to generate the url to put into action the attribute, and the other to generate hidden fields containing any additional parameters to the action. You should always use two sets. The form then becomes:

  <form action="{formurl 'mymodule~default:save'}" method="POST">
  <fieldset> <legend>Indicate your identity</legend>
     {formurlparam}
     <table>
      ...
      </table>
  </fieldset>
  <p><input type="submit" value="Ok" />
  </form>

The resulting form will be the same as the first example, but the module is more portable.

In the action used to process the data, you retrieve data through $this->param('a_field') in your controller. You have other similar methods, like $this->intParam('a_field'), $this->floatParam('a_field') and $this->boolParam('a_field'), which can directly retrieve values from a particular type (see the page on controllers).

You can use also jFilter, which is a class to verify the format of the data (it uses PHP's filter extension). Example:

    function save() {
       $email = $this->param('email');
       if ($email === null) {
             //.. here error, the email is missing
       }
       if(!jFilter::isEmail($email)){
             // error, the email is bad
       }
       //....
    }

See the documentation reference jFilter.