other in entity choice list form - php

Question

I'm new to symfony. I have a drop down in a form with data fetched from DB.
$builder->add('category', 'entity', array(
'label' => 'category',
'class' => 'MyBundle:category',
'expanded' => false,
'multiple' => false,
'mapped' => false,
'empty_value' => 'category'
));
$builder->add('other_category', 'text', array(
'label' => 'category',
'required' => false,
'invalid_message' => 'Please enter a valid category',
'mapped' => false,
));
the user can also add new category to the table. when other is selected from drop down, the 'other_category' input field is shown, else its hidden.
'Other' was added to drop down with the help of this code.
public function finishView(FormView $view, FormInterface $form, array $options)
{
$new_choice = new ChoiceView(array(), 'other', 'Other');
$view->children['category']->vars['choices'][] = $new_choice;
}
If a option is selected from drop down the form works fine. Data gets stored without any error. But if user selects 'other' and enters a new category the page reloads with 'This value is no valid' under the category options and there is no form validation for the 'other_category' entered by user.
Can someone help me with the form validation and also entering of a new category or suggest a better way to implement the above functionality.

Answer 1

The validation error is happening because the form field type is Entity, but there is no "MyBundle:category" entity with the identifying value "other".
You've not specified the "choice_label" property in your Entity form type so I'll assume your "MyBundle:category" entity has a __toString() function. This would mean none of the "MyBundle:category" entities return "other" in their __toString() function.
I can think of two options to work around this right now:
1) Add a "MyBundle:category" entity with value "other". This is the easiest way, but it's fairly assumed you don't want such a category to exist in your database.
2) Load the list of "MyBundle:category" entities in advance from your controller, build them into an associative array, append your "other" option to the array, then pass that array to the form. You'd need to swap the Entity form type for a Choice type and use the categories array as the choices.
If your form is a FormType class you'll need to pass the array in with the class constructor.
If you don't mind having a new category with an "other" value in your category table, just add it. Otherwise go for option 2, which won't make much difference to what you do after receiving the submitted form as this form field isn't mapped to an entity property anyway.