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Doctrine is an ORM: an object relational mapper.

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That's a fancy way of saying that,
for each table in the database,

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we will have a corresponding class in PHP.

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And for each column on that table,
there will be a property in that class.

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When you query for a row in a table,
Doctrine will give you an object

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with that row's data set on the properties.

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So if you want to create a database table
in Doctrine, the way you do that is actually

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by creating the class it will map to.

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These "classes" that map to tables
have a special name: entity classes.

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You can create an entity class by hand -
there's nothing very special about them.

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But... come on!

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There's a much easier way.

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Find your terminal and run one of
my favorite bin/console commands:

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php bin/console make:entity You can also run:
symfony console make:entity It doesn't matter

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in this case, because this command won't
talk directly to the database, and so,

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it doesn't need the environment variables.

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This command just generates code.

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Now remember: the whole point of
our site is for witches and wizards

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to ask questions and then post answers.

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So the very first thing we
need is a Question entity.

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So, a question table in the database.

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Enter Question.

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The command immediately starts asking
what properties we want, which really,

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also means what columns we want in the table.

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Let's add a few.

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Call the first one name - that
will be the short name or "title"

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of the question like "Reversing a Spell".

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The command then asks what "type" we want.

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Doctrine has its own type system: enter "?"

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to see the full list.

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These aren't MySQL column
types, but each maps to one.

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For example, a string maps
to a VARCHAR in MySQL.

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And there are a bunch more.

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In our case, choose string: that's good
for any text 255 characters or less.

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For the column length, I'll use the default 255.

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The next question says: Can this
field be nullable in the database?

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Say "No". This means that the column
will be required in the database.

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And... congrats!

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We just added our first field!

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Let's add a few more.

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Call the next slug: this will be the URL-safe
version of the name that shows up in the URL.

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It will also be a string, let's
set its length to 100 and,

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once again, I'll say "no" to "nullable".

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For the actual body of the
question, let's call it question.

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This will be long, so we
can't use the string type.

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Instead, use text...

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and make this also required in the database.

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Add one more field: askedAt.

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This will be a date field - kind
of like a "published at" field.

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For the type, ooh!

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It recommends datetime -
that is exactly what we want!

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Hit enter and this time say "yes" to nullable.

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The idea is that users will be able to start
writing a question and save it to the database

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with a null askedAt because it's not finished.

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When the user is finished and ready to
post it, then we would set that value.

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And... we're done!

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Hit enter one more time to exit make:entity.

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So... what did this do?

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Well, first, I'll tell you that this made
absolutely no changes to our database:

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we do not have a question database table yet.

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If you scroll back up to the top of the
command, you can see that it created 2 files:

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src/Entity/Question.php and
src/Repository/QuestionRepository.php.

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For now, completely ignore the
repository class: it's not important

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yet and we'll talk about it later.

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This entity class, however, is super important.

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Go open it up: src/Entity/Question.php.

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As we talked about, we're going
to have one class per table.

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The first thing I want you to notice is that...

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there's nothing special about this class.

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It's a boring, normal class...

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it doesn't even extend a base class!

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It has several private properties and, to
access those, the command generated getter

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and setter methods, like
getName(), getSlug() and setSlug().

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It's just about the most
boring class you'll ever see.

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But of course, if Doctrine is going
to map this class and its properties

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to a database table, it's
needs to know a few things.

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For example, it needs to know
that the name property should map

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to a name column and that its type is a string.

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The way that Doctrine does
this is by reading annotations.

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Well, you can also use XML,
but I love annotations.

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For example, the @ORM\Entity() above the
class is what actually tells Doctrine: Hey!

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This is not just a normal, boring PHP class.

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This is an "entity": a class that I want
to be able to store in the database.

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Then, the @ORM\Column() above the
properties is how Doctrine knows

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which properties should be stored
in the table and their types.

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Now, there are a bunch of different annotations
and options you can use to configure Doctrine.

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Most are pretty simple - but let
me show you am awesome reference.

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Search for doctrine annotations reference
to find a really nice spot on their site

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where you can see a list of all the different
possible annotations and their options.

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For example, @Column() tells
you all the different options

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that you can pass to it, like a name option.

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So if you wanted to control
the name of the slug column -

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instead of letting Doctrine
determine it automatically -

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you would do that by adding a name option.

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One of the other annotations
that you'll see here is @Table.

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Oh, and notice, in the docs, the
annotation will be called @Table.

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But inside Symfony, we always use @ORM\Table.

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Those are both referring to the same thing.

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Anyways, if you wanted to control the name
of the table, we could say @ORM\Table()

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and pass it name="" with some cool table name.

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But I won't bother doing that because Doctrine
will guess a good table name from the class.

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Oh, and by the way, the auto-completion that
you're seeing on the annotations comes from the

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"PHP Annotations" plugin in PhpStorm.

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Ok: status check!

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The make:entity command helped
us create this new entity class,

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but it did not talk to the database.

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There is still no question table.

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How do we create the table?

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By generating a migration.

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Doctrine's migrations system is amazing.

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It will even allow us to perform table
changes with basically zero work.

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Let's find out how next.