How to build nested forms in symfony?

@denis 

To build nested forms in Symfony, you would need to create separate form classes for each nested form and then connect them together in the parent form.

Here is a step-by-step guide to build nested forms in Symfony:

1. Create a Form for the Parent Entity: Generate a form class for the parent entity using the command:

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php bin/console make:form ParentEntity

1. Add Child Form Type Class: Generate a form class for the child entity using the command:

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php bin/console make:form ChildEntity

1. Connect Child Form to Parent Form: In the Parent form class, add the child form as a field using the EntityType or CollectionType field type:

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$builder->add('childEntity', ChildEntityType::class);

1. Configure Child Form Options: In the parent form class, configure the options for the child form:

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$builder->add('childEntity', ChildEntityType::class, [
    'data_class' => ChildEntity::class
]);

1. Render Child Form in Parent Form Template: In the parent form template (e.g., parent_entity_form.html.twig), render the child form using the form_row() or form_widget() function:

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{{ form_row(form.childEntity) }}

1. Process Form Submissions: In the controller handling the form submission, process the parent and child form submissions separately:

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$form = $this->createForm(ParentEntityType::class, $parentEntity);
$form->handleRequest($request);

if ($form->isSubmitted() && $form->isValid()) {
    // Handle parent form submission

    // Access child form data
    $childData = $form->get('childEntity')->getData();
    // Handle child form submission
}

By following these steps, you can create nested forms in Symfony and connect multiple form entities together for complex form structures.