Choose the field to filter not a FilterClass

[Charlie-Lucas]

When you create a widget Filter you can choose a filter in the list but each filter is set for a specific association and a specific field name. So we need to re-create a filter every time we want filter on a property.
For me the best process to generate a filter is:

1. choose the listing
2. list fields of the entity listed and select
3. choose the default filter based on the field : string, onetomany, ... or a specific filter that was created for this type of relation.

Each filter can be define with a list of metadatas to define the relation it can be used:
services.yml

    acme.user_gender_filter:
        class: AcmeBundle\Filter\UserGenderFilter
        parent: victoire_filter.filter.many_to_one_filter
        tags:
            - { name: form.type }
            - { name: victoire_core.filter,  relation: ManyToOne, targetEntity: AcmeBundle\Entity\User}

Book.php

class Book
{
     /**
      * @ORM\ManyToOne(targetEntity="AcmeBundle\Entity\User", inversedBy="books")
      */
     private $author;

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $name;
}

Then in this example we can create a filter on a list of books like this:

If "Default" filter is the only available filter the select of filters is not display.