Scroll down to the script below, click on any sentence (including terminal blocks!) to jump to that spot in the video!Cool, got it!
Is the relationship required in the database? I mean, could I save a
without setting a
Genus on it? Actually, I could! Unlike a normal column, relationship
columns - for whatever reason - are optional by default. But does it make sense
to allow a
GenusNote without a
Genus? No! That's crazy talk! Let's prevent it.
ManyToOne annotation and add a new annotation below it:
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JoinColumn annotation controls how the foreign key looks in the database.
And obviously, it's optional. Another option is
onDelete: that literally
ON DELETE behavior in your database - the default is
but you can also use
Anyways, we just made a schema change - so time to generate a migration!
This time, I'll be lazy and trust that it's correct. Run it!
Ah, it explodes! Null value not allowed? Why? Think about what's happening: we have
a bunch of existing
GenusNote rows in the database, and each still has a
genus_id. We can't set that column to
NOT NULL because of the data that's already
in the database.
If the app were already deployed to production, we would need to fix the migration:
maybe UPDATE each existing
genus_note and set the
genus_id to the first
in the table.
But, alas! We haven't deployed to production yet: so there isn't any existing production database that we'll need to migrate. Instead, just start from scratch: drop the database completely, re-create it, and re-migrate from the beginning:
./bin/console doctrine:database:drop --force
Phew! Now it works great.
If you still get an error while running the migration, it's because of a MySQL change! Find the details here: http://bit.ly/migrations-tweak
Last step! Our fixtures are broken: we need to associate each
GenusNote with a
Genus. We know how to set normal properties, like
But how can we set relations? As usual with Alice: it's so nice. Use
then the internal name of one of the 10 genuses - like
genus_1. That's it!
But, you know what? That's not awesome enough. I really want this to be a random
Genus. Ok: change that
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Alice will now look at the 10 Genus objects matching this pattern and select a random one each time.
Reload the fixtures:
It's alive! Check out the results again with
./bin/console doctrine:query:sql 'SELECT * FROM genus_note'
Every single one has a random genus. Do you love it? I love it.