My_form_demo

Activity

• Create a new module named my_form_demo.
• Recreate the ColourForm example we saw in the previous unit.
• You'll need to create a form class and a form route.
• Name the class ColourForm.

Copy/pasting the example code from the previous unit without some modifications won't work: you'll need to ensure the module name, form class name, and route name are correct.

Activity

In your ColourForm, implement the submit handler (make it do something useful):

• Retrieve the submitted colour value.
• Redirect the user to /colour/<favourite colour>, replacing <favourite colour> with the value the user submitted.

1. Retrieving submitted values

The $form array that you receive in your submitForm() method contains the original form definition, including all of the fields' default values, if any. The $form_state object that you receive in your submitForm() method contains all the submitted values.

You can retrieve submitted values using $form_state->getValue(), passing along the name of the field whose value you want to retrieve:

$submitted_colour = $form_state->getValue('fav_colour');

2. Redirecting the user after form submit

Have a look at the reference documentation for FormStateInterface, and inspect the available properties and methods.

Two methods that look suitable for redirecting after submit are:

• setRedirect()
• setRedirectUrl()

You are going to use setRedirect() because it involves slightly less code than using setRedirectUrl().

From the setRedirect() documentation you learn:

• This method needs at least one parameter: the full name of the route you want to redirect to.
• This method accepts an optional 2nd parameter: an array with route parameter values.

In other words, you'll need to do something like:

• Parameter 1: the name you gave to the route you created in 2A.
• Parameter 2: an array with one element: ['key' => 'value']
  • key: the name of the route parameter as you used it in the route definition (you specified '/colour/{fav}', so 'fav' is the name of your route parameter
  • value: the submitted colour value.

The code will be similar to this:

$submitted_value = $form_state->getValue('name_of_field');
$form_state->setRedirect('full_name_of_route', [
 'param_name_in_route' => $submitted_value,
]);

→ be sure to replace 'full_name_of_route' and 'param_name_in_route' with the correct names as you specified them in your route definition.