Symfony form: The selected choice is invalid - php

Question

My symfony app have this entity:
<?php
namespace App\Entity;
class Lead
{
private ?string $zipCode;
private ?string $city;
public function getZipCode(): ?string
{
return $this->zipCode;
}
public function setZipCode(string $zipCode): self
{
$this->zipCode = $zipCode;
return $this;
}
public function getCity(): ?string
{
return $this->city;
}
public function setCity(string $city): self
{
$this->city = $city;
return $this;
}
}
And the Form LeadType is :
$builder->add('zipCode', TextType::class, [
'attr' => [
'placeholder' => 'Ex : 44000',
'onchange' => 'cityChoices(this.value)',
]
])
->add('city', ChoiceType::class, [
'choices' => [],
'attr' => ['class' => 'form-control'],
'choice_attr' => function () {return ['style' => 'color: #010101;'];},
]);
When the user enters a zip code, the javascript function cityChoices() add the select options using an external api like:
My problem is in the controller that the form is invalid. Because the user has selected a city that was not offered in the choices of LeadType ('choices' => []).
Here is the error:
0 => Symfony\Component\Form\FormError {#3703 ▼
#messageTemplate: "The selected choice is invalid."
#messageParameters: array:1 [▼
"{{ value }}" => "Bar-le-Duc"
]
How to make the choice valid?

Answer 1

Completly #craight
I add to the form :
->addEventListener(FormEvents::PRE_SUBMIT, function(FormEvent$event){
$form = $event->getForm();
$city = $event->getData()['city'];
if($city){
$form->add('city', ChoiceType::class, ['choices' => [$city => $city]]);
}
})
When pre submit, I update choices and I put only the user select 'choices' => ['Bar-le-Duc' => 'Bar-le-Duc'],
The form becomes valid in the controller