Update Query & Rich vs Anemic Models

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On the show page, we can now up vote or down vote the question... mostly. In the controller, we read the direction POST parameter to know which button was clicked and change the vote count. This doesn't save to the database yet, but we'll do that in a few minutes.

Adding upVote and downVote Methods

Before we do, we have another opportunity to improve our code. The logic inside the controller to increase or decrease the vote isn't complex, but it could be simpler and more descriptive.

In Question, at the bottom, add a new public function called upVote(). I'm going make this return self. Inside, say $this->votes++. Then, return $this... just because that allows method chaining - all of the setter methods return $this.

Copy this, paste, and create another called downVote() that will do $this->votes--. I'm not going to bother adding any PHP documentation above these, because... their names are already so descriptive: upVote() and downVote()!

I love doing this because it makes the code in our controller so nice. If the direction is up, $question->upVote(). If it's down, $question->downVote().

How beautiful is that? And when we move over to try it... we're still good!

Rich vs Anemic Models

We've now added three custom methods to Question: upVote(), downVote() and getVotesString(). And this touches on a somewhat controversial topic related to entities. Notice that every property in our entity has a getter and setter method. This makes the entity super flexible: you can get or set any field you want.

But sometimes you might not need - or even want - a getter or setter method. For example, do we really want a setVotes() method? Should anything in our app be able to set the vote directly to any number? Probably not. Probably we will always want to use upVote() or downVote().

Now, I will keep this method... but only because we're using it in QuestionController. In the new() method... we're using it to set the fake data.

But this touches on a really interesting idea: by removing any unnecessary getter or setter methods in your entity and replacing them with more descriptive methods that fit your business logic - like upVote() and downVote() - you can, little by little, give your entities more clarity. upVote(), and downVote() are very clear & descriptive. Someone calling these doesn't even need to know or care how they work internally.

Some people take this to an extreme and have almost zero getter and setter methods on their entities. Here at Symfonycasts, we tend to be more pragmatic. We usually have getters and setters method, but we always look for ways to be more descriptive - like upVote() and downVote().

Updating an Entity in the Database

Okay, let's finish this! In our controller, back down in questionVote(), how can we execute an update query to save the new vote count to the database? Well, no surprise, whenever we need to save something in Doctrine, we need the entity manager.

Add another argument: EntityManagerInterface $entityManager. Then, below, replace the dd($question) with $entityManager->flush().

Done! Seriously! Doctrine is smart enough to realize that the Question object already exists in the database and make an update query instead of an insert. We don't need to worry about "is this an insert or an update" at all? Doctrine has that covered.

No persist() on Update?

But wait, didn't I forget the persist() call? Up in the new() action, we learned that to insert something, we need to get the entity manager and then call persist() and flush().

This time, we could have added persist(), but we don't need to. Scroll back up to new(). Remember: the point of persist() is to make Doctrine aware of your object so that when you call flush(), it knows to check that object and execute whatever query it needs to save that into the database, whether that is an INSERT of UPDATE query.

Down in questionVote(), because Doctrine was used to query for this Question object... it's already aware of it! When we call flush(), it already knows to check the Question object for changes and performs an UPDATE query. Doctrine is smart.


Ok, now that this is saving... what should our controller return? Well, usually after a form submit, we will redirect somewhere. Let's do that. How? return $this->redirectToRoute() and then pass the name of the route that we want to redirect to. Let's use app_question_show to redirect to the show page and then pass any wildcard values as the second argument: slug set to $question->getSlug().

Two things about this. First, until now, we've only generated URLs from inside of Twig, by using the {{ path() }} function. We pass the same arguments to redirectToRoute() because, internally, it generates a URL just like path() does.

And second... more of a question. On a high level... what is a redirect? When a server wants to redirect you to another page, how does it do that?

A redirect is nothing more than a special type of response. It's a response that has a 301 or 302 status code and a Location header that tells your browser where to go.

Let's do some digging and find out how redirectToResponse() does this. Hold Command or Ctrl and click redirectToRoute() to jump to that method inside of AbstractController. This apparently calls another method: redirect(). Hold Command or Ctrl again to jump to that.

Ah, here's the answer: this returns a RedirectResponse object. Hold Command or Ctrl one more time to jump into this class.

RedirectResponse live deep in the core of Symfony and it extends Response! Yes this is just a special subclass of Response that's really good at creating redirect responses.

Let's close all of these core classes. The point is: the redirectToRoute() method doesn't do anything magical: it simply returns a Response object that's really good at redirecting.

Ok: testing time! Spin over to your browser and go back to the show page. Right now this has 10 votes. Hit "up vote" and... 11! Do it again: 12! Then... 13! Downvote... 12. We got it!

Like I said earlier, in a real app, when we have user authentication, we might prevent someone from voting multiple times. But, we can worry about that later.

Next: we have created a way to load dummy data into our database via the /questions/new page. But... it's pretty hacky.

Let's replace this with a proper fixtures system.

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