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08.

Persisting to the Database

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We have a beautiful entity class and, thanks to the migrations that we just executed, we have a corresponding question table in the database. Time to insert some data!

Think "Classes", not "Tables"

One of the key philosophies of Doctrine is that it doesn't want you to think about tables and columns. Doctrine wants you to think about classes and properties... and then leave all the details of saving and querying to a database table up to it to worry about.

So instead of asking:

How can I insert a new row in the question table?

We need to think:

Let's create a Question object, populate it with data and then ask Doctrine to save it.

Creating a Question Endpoint

To play with all of this, let's add a new, sort of, fake page - /questions/new. When we go there, I want a new question to be added to the database.

Open up src/Controller/QuestionController.php, which already holds the homepage and show page. At the bottom, add public function and... let's call it new(). Above, say @Route() with /questions/new.

64 lines | src/Controller/QuestionController.php
// ... lines 1 - 10
class QuestionController extends AbstractController
{
// ... lines 13 - 55
/**
* @Route("/questions/new")
*/
public function new()
{
// ... line 61
}
}

To keep things simple, return a new Response() - the one from HttpFoundation - with Time for some Doctrine magic!

64 lines | src/Controller/QuestionController.php
// ... lines 1 - 7
use Symfony\Component\HttpFoundation\Response;
// ... lines 9 - 10
class QuestionController extends AbstractController
{
// ... lines 13 - 55
/**
* @Route("/questions/new")
*/
public function new()
{
return new Response('Time for some Doctrine magic!');
}
}

There's no Doctrine logic yet, but this should work. At the browser, hit enter and... woh! It doesn't work! There's no error, but this is not the page we expected. It looks like the question show page. And, in fact, if you look down on the web debug toolbar... yea! The route is app_question_show!

The problem is that the url /questions/new does match this route! It look like "new" is the slug. Routes match from top to bottom and Symfony stops as soon as it finds the first matching route. So the easiest fix is to just move the more specific route above this one.

64 lines | src/Controller/QuestionController.php
// ... lines 1 - 10
class QuestionController extends AbstractController
{
// ... lines 13 - 25
public function homepage()
{
// ... line 28
}
// ... line 30
/**
* @Route("/questions/new")
*/
public function new()
{
return new Response('Time for some Doctrine magic!');
}
/**
* @Route("/questions/{slug}", name="app_question_show")
*/
public function show($slug, MarkdownHelper $markdownHelper)
{
// ... lines 44 - 61
}
}

This doesn't happen too often, but this is how I handle it.

Now when we go refresh... got it!

Creating the Question Object

Ok: time to work! Eventually - in a future tutorial - this page will render a form where the user can fill out all the information about their question. When they submit, we will save that question to the database.

But we're not going to talk about Symfony forms yet. Instead, let's "fake it" inside the controller. Let's create a Question object, set some hardcoded data on it and ask Doctrine to save it.

And because there is nothing special about our entity class, instantiating it looks exactly like you would expect: $question = new Question() and I'll auto-complete this so that PhpStorm adds the Question use statement.

87 lines | src/Controller/QuestionController.php
// ... lines 1 - 4
use App\Entity\Question;
// ... lines 6 - 11
class QuestionController extends AbstractController
{
// ... lines 14 - 34
public function new()
{
$question = new Question();
// ... lines 38 - 59
}
// ... lines 61 - 85
}

Next, call $question->setName('Missing pants') - an unfortunate magical side effect of an incorrect spell.

87 lines | src/Controller/QuestionController.php
// ... lines 1 - 4
use App\Entity\Question;
// ... lines 6 - 11
class QuestionController extends AbstractController
{
// ... lines 14 - 34
public function new()
{
$question = new Question();
$question->setName('Missing pants')
// ... lines 39 - 59
}
// ... lines 61 - 85
}

And ->setSlug('missing-pants') with a random number at the end so that each one is unique.

87 lines | src/Controller/QuestionController.php
// ... lines 1 - 4
use App\Entity\Question;
// ... lines 6 - 11
class QuestionController extends AbstractController
{
// ... lines 14 - 34
public function new()
{
$question = new Question();
$question->setName('Missing pants')
->setSlug('missing-pants-'.rand(0, 1000))
// ... lines 40 - 59
}
// ... lines 61 - 85
}

For the main part of the question, call ->setQuestion() and, because this is long, I'll use the multiline syntax - <<<EOF - and paste in some content. You can copy this from the code block on this page or use any text.

87 lines | src/Controller/QuestionController.php
// ... lines 1 - 4
use App\Entity\Question;
// ... lines 6 - 11
class QuestionController extends AbstractController
{
// ... lines 14 - 34
public function new()
{
$question = new Question();
$question->setName('Missing pants')
->setSlug('missing-pants-'.rand(0, 1000))
->setQuestion(<<<EOF
Hi! So... I'm having a *weird* day. Yesterday, I cast a spell
to make my dishes wash themselves. But while I was casting it,
I slipped a little and I think `I also hit my pants with the spell`.
When I woke up this morning, I caught a quick glimpse of my pants
opening the front door and walking out! I've been out all afternoon
(with no pants mind you) searching for them.
Does anyone have a spell to call your pants back?
EOF
);
// ... lines 52 - 59
}
// ... lines 61 - 85
}

The last field is $askedAt. Let's add some randomness to this: if a random number between 1 and 10 is greater than 2, then call $question->setAskedAt(). Remember: askedAt is allowed to be null in the database... and if it is, we want that to mean that the user hasn't published the question yet. This if statement will give us a nice mixture of published and unpublished questions.

87 lines | src/Controller/QuestionController.php
// ... lines 1 - 4
use App\Entity\Question;
// ... lines 6 - 11
class QuestionController extends AbstractController
{
// ... lines 14 - 34
public function new()
{
$question = new Question();
$question->setName('Missing pants')
->setSlug('missing-pants-'.rand(0, 1000))
->setQuestion(<<<EOF
// ... lines 41 - 49
EOF
);
if (rand(1, 10) > 2) {
// ... line 54
}
// ... lines 56 - 59
}
// ... lines 61 - 85
}

Also remember that the $askedAt property is a datetime field. This means that it will be a DATETIME type in MySQL: a field that is ultimately set via a date string. But in PHP, instead of dealing with strings, thankfully we get to deal with DateTime objects. Let's say new \DateTime() and add some randomness here too: sprintf('-%d days') and pass a random number from 1 to 100.

87 lines | src/Controller/QuestionController.php
// ... lines 1 - 4
use App\Entity\Question;
// ... lines 6 - 11
class QuestionController extends AbstractController
{
// ... lines 14 - 34
public function new()
{
$question = new Question();
$question->setName('Missing pants')
->setSlug('missing-pants-'.rand(0, 1000))
->setQuestion(<<<EOF
// ... lines 41 - 49
EOF
);
if (rand(1, 10) > 2) {
$question->setAskedAt(new \DateTime(sprintf('-%d days', rand(1, 100))));
}
// ... lines 56 - 59
}
// ... lines 61 - 85
}

So, the askedAt will be anywhere from 1 to 100 days ago.

Ok! Our Question object is done! Add a dd($question) at the bottom:

87 lines | src/Controller/QuestionController.php
// ... lines 1 - 4
use App\Entity\Question;
// ... lines 6 - 11
class QuestionController extends AbstractController
{
// ... lines 14 - 34
public function new()
{
$question = new Question();
$question->setName('Missing pants')
->setSlug('missing-pants-'.rand(0, 1000))
->setQuestion(<<<EOF
// ... lines 41 - 49
EOF
);
if (rand(1, 10) > 2) {
$question->setAskedAt(new \DateTime(sprintf('-%d days', rand(1, 100))));
}
dd($question);
// ... lines 58 - 59
}
// ... lines 61 - 85
}

then move over, refresh and... hello nice, boring Question object! Notice that the id property is still null because we haven't saved it to the database yet.

The EntityManagerInterface Service

So... how do we ask Doctrine to save this? When we installed Doctrine, one of the packages we downloaded was DoctrineBundle. From the Symfony Fundamentals course, you might remember that the main thing that a bundle gives us is new services in the container. And even though Doctrine is super powerful, it turns out that there is just one Doctrine service that we'll use 99% of the time. This one service is capable of both saving and fetching... which... is really all Doctrine does.

To find the service, head to your terminal and run:

php bin/console debug:autowiring doctrine

This returns several services, but most are lower level. The one we want - which is the most important service by far in Doctrine - is EntityManagerInterface.

Let's go use it! Back in the controller, add a new argument to autowire this: EntityManagerInterface $entityManager.

93 lines | src/Controller/QuestionController.php
// ... lines 1 - 6
use Doctrine\ORM\EntityManagerInterface;
// ... lines 8 - 12
class QuestionController extends AbstractController
{
// ... lines 15 - 35
public function new(EntityManagerInterface $entityManager)
{
// ... lines 38 - 65
}
// ... lines 67 - 91
}

persist() and flush()

Below, remove the dd(). How do we save? Call $entityManager->persist() and pass the object to save. And then $entityManager->flush().

93 lines | src/Controller/QuestionController.php
// ... lines 1 - 6
use Doctrine\ORM\EntityManagerInterface;
// ... lines 8 - 12
class QuestionController extends AbstractController
{
// ... lines 15 - 35
public function new(EntityManagerInterface $entityManager)
{
// ... lines 38 - 57
$entityManager->persist($question);
$entityManager->flush();
// ... lines 60 - 65
}
// ... lines 67 - 91
}

Yes, you need both lines. The persist() call simply says:

Hey Doctrine! Please be "aware" of this Question object.

The persist line does not make any queries. The INSERT query happens when we call flush(). The flush() method says:

Yo Doctrine! Please look at all of the objects that you are "aware" of and make all the queries you need to save those.

So this is how saving looks: a persist() and flush() right next to each other. If you ever needed to, you could call persist() on 5 different objects and then call flush() once at the end to make all of those queries at the same time.

Anyways, now that we have a Question object, let's make the Response more interesting. I'll say sprintf with:

Well hallo! The shiny new question is id #%d, slug: %s

Passing $question->getId() for the first placeholder and $question->getSlug() for the second.

93 lines | src/Controller/QuestionController.php
// ... lines 1 - 6
use Doctrine\ORM\EntityManagerInterface;
// ... lines 8 - 12
class QuestionController extends AbstractController
{
// ... lines 15 - 35
public function new(EntityManagerInterface $entityManager)
{
// ... lines 38 - 57
$entityManager->persist($question);
$entityManager->flush();
return new Response(sprintf(
'Well hallo! The shiny new question is id #%d, slug: %s',
$question->getId(),
$question->getSlug()
));
}
// ... lines 67 - 91
}

Ok, back at the browser, before saving, the Question object had no id value. But now when we refresh... yes! It has an id! After saving, Doctrine automatically sets the new id on the object. We can refresh over and over again to add more and more question rows to the table.

Let's go see them! If you ever want to make a query to see something, Doctrine has a handy bin/console command for that:

symfony console doctrine:query:sql 'SELECT * FROM question'

And... yes! Here is a dump of the 8 rows in the table.

Next: we know how to save. So how can we query to fetch data?