EntityType: Custom Query

Right click and "Inspect Element". Look at the value of each option: it's the id of that user in the database. So, when we choose an author, this is the value that will be submitted to the server: this number. Just remember that.

Time to author another award-winning article:

Pluto: I didn't want to be a Planet Anyways

Set the publish date to today at any time, select an author and... create! Yes! The author is spacebar3@example.com and it is published.

This is way more amazing than it might look at first! Sure, the EntityType is cool because it makes it easy to create a drop-down that's populated from the database. Blah, blah, blah. That's fine. But the truly amazing part of EntityType is its data transformer. It's the fact that, when we submit a number to the server - like 17 - it queries the database and transforms that into a User object. That's important because the form system will eventually call setAuthor(). And this method requires a User object as an argument - not the number 17. The data transformer is the magic that makes that happen.

Creating a Custom Query

We can use this new knowledge to our advantage! Go back to the create form. What if we don't want to show all of the users in this drop-down? Or, what if we want to control their order. How can we do that?

Normally, when you use the EntityType, you don't need to pass the choices option. Remember, if you look at ChoiceType, the choices option is how you specify which, ah, choices you want to show in the drop-down. But EntityType queries for the choices and basically sets this option for us.

To control that query, there's an option called query_builder. Or, you can do what I do: be less fancy and simply override the choices option entirely. Yep, you basically say:

Hey EntityType! Thanks... but I can handle querying for the choices myself. But, have a super day.

Injecting Dependencies

To do this, we need to execute a query from inside of our form class. And to do that, we need the UserRepository. But... great news! Form types are services! So we can use our favorite pattern: dependency injection.

Create an __construct() method with an UserRepository argument. I'll hit alt+enter, and select "Initialize Fields" to create that property and set it. Down below, pass choices set to $this->userRepository and I'll call a new method ->findAllEmailAlphabetical().

Copy that name, go to src/Repository/, open UserRepository, and create that method. Use the query builder: return $this->createQueryBuilder('u') and then ->orderBy('u.email', 'ASC'). Finish with ->getQuery() and ->execute().

Above the method, we know that this will return an array of User objects. So, let's advertise that!

I love it! This makes our ArticleFormType class happy. I think we should try it! Refresh! Cool! The admin users are first, then the others.

So... is EntityType Still Needed?

But... wait. Now that we're manually setting the choices option... do we even need to use EntityType anymore? Couldn't we switch to ChoiceType instead?

Actually... no! There is one super critical thing that EntityType is still giving us: data transformation. When we submit the form, we still need the submitted id to be transformed back into the correct User object. So, even though we're querying for the options manually, it is still doing this very important job for us. Remember: the true power of a field type is this data transformation ability.

Next: let's add some form validation! It might work a little differently than you expect.