[RFC] [Form] custom choice loader article

[HeahDude]

Hey all,

I'm thinking about writing a short article pointing an example of a custom ChoiceLoaderInterface to optimize performances in form submission using a custom choice_value option.

I've some (maybe dumb) questions:

• do you think it would be useful?

• do you think it should be part of the doc?

• can I host an article directly on GitHub, or should I handle a blog on my website?

  Thanks!

[xabbuh]

If we have a real use case that calls for custom implementation of the interface, I would be 👍 for adding an article to the docs.

[HeahDude]

Currently the EntityType has an example in the introduction with users and a custom query builder ordering them by username.
We could use the same example, which implies to not use choice_value option so ids are used to load only selected users.
I propose some changes to the EntityType reference:

1. in Basic Usage section, explicit the option multiple => true, since the fields is called "users" anyway
2. mention that ids are used as choices values to optimize loading done in [Form] fixed EntityType choice options #6444
3. add a link or a section following Using a Custom Query for the Entities, with a custom choice_name option to submit a username instead of an id through API, but needs a custom loader to optimize the query when loading the submitted values.
4. maybe change the section Using Choices, to suggest using ChoiceType with loaded choices, and a transformer to return an ArrayCollection in model data (dealing with DataTransformer cookbook – strip_tags is a bad example? #6431 at the same time?).
5. maybe keep using users instead of categories in the choice_label option example ?

[HeahDude]

Ok I've updated previous post to take #6444 into account. I could maybe handle more there too.

[HeahDude]

Maybe off topic but what about a UsersType in the SecurityBundle taking the user provider as argument and using it in a custom choice loader implementation ?