How to get subcategories in symfony?

Question

symfony

There is a table with categories of the 2nd and 3rd levels.
id . parent_id . name
How to describe YML and write a request in the controller so that I can get the child categories of the 2nd and 3rd levels?

Answer 1

Have a look at https://github.com/KnpLabs/DoctrineBehaviors#tree

Answer 2

...\ProductCategory:
    type: entity
    table: product_categories
    ...
    manyToOne:
        parent:
            targetEntity: ...\ProductCategory
    id:
        id:
            type: integer
            id: true
            generator:
                strategy: AUTO
    fields:
        name:
            type: string
            length: 255
        ...