Fetching Relations

Hey @Farry

It's because Entities are proxied this allows to delay running sql query and the data will be loaded when you try to access this data. But if you want to see all data you can add fetch="EAGER" to the @ORM\OneToMany() annotation. It may cause performance issues.

Cheers!

So there is no valid way of doing this without risk of performance issues? I don't understand why this problem is caused specificly here, while chaining objects is a normal thing right?
Lets say you want user images and you only have the userID in the url. Then you write something like this:
$user->getPosts()->getImages();
On other places on my website, it works just fine. So I cant understand why I am getting this error on a specific part which is about machines in the factory.
$machine->getProduct()->getControlPlan();
Its not showing the controlplan for some reason.

oh that is tricky! You can try to make custom queries with QueryBuilder using joins and select all data you need explicitly. Than data you not selected will be queried lazyly, but everything mentioned in ->select() will be abvailable

This will allow you to bypass perrformance issues, but it really depends on you project and amount of data you trying select

Cheers!

Hey @Farry7!

I'm not sure why a composer update would cause this, but on a high level, this error means:

Hey! I see an annotation (e.g. @Slug) but there is no corresponding use statement in that class for it.

However, the fact that it lists the entire annotation class name - Gedmo\Mapping\Annotation\Slug - (and it's correct), leads me to think that the use statement IS there. In that case, it simply can't find this class in your project! Did you somehow uninstall the doctrine-extensions library (this class comes from https://github.com/doctrine-extensions/DoctrineExtensions, which is a dependency of the stof doctrine extensions bundle)?

Cheers!

Hey Farry,

Which trait did you use? There is one specific for entities, I believe it's called "TimestampableEntity". Give it a try and let me know

Cheers!

Thanks, the migration worked. But now when I am adding an input to the database, it gives an error saying that:
"An exception occurred while executing 'INSERT INTO measurement (measurement, created_at, updated_at, measurement_meetstaat_id) VALUES (?, ?, ?, ?)' with params [34, null, null, 125]:"

I also generated Getters and Setters on the Entity. Do I also need to do something else?

I believe you forgot to enable the doctrine extension. Here you can see how to do it https://symfony.com/doc/cur...

I did it. Now it says the following:
The Doctrine connection "other" referenced in service "stof_doctrine_extensions.listener.timestampable" does not exist. Available connections names: "default".

Do I have to manually add setCreatedAt(), setUpdatedAt() in the controller? I thought the trait would take care of some of it.

my stof_doctrine_extensions.yaml:

stof_doctrine_extensions:
    default_locale: en_US
    orm:
        default:
            sluggable: true
            tree: true
            timestampable: false # not needed: listeners are not enabled by default
        other:
            timestampable: true

EDIT: I just added a $date = new \DateTime(); and passed it through. Now it works. At first, I thought that Symfony might handle some of it in the background.

The extension bundle should take care of it. It works via Doctrine listeners. The problem is the other connection configuration is just an example, you should put it on the "default" one (unless you're using multiple databases)

Cheers!

Hey Farry,

The ParamConverter grabs the query parameter from the URL and try to fetch an object based on it. You can read more about it here https://symfony.com/doc/cur...

Cheers!

Hey Joe L.

We added the TimestampableEntity trait to the Comment class in the first video, you may have lost it but here it is :)
https://symfonycasts.com/screencast/doctrine-relations/comment-entity?playAt=237

Cheers!

Yeah - I retraced my steps and saw I missed one!!!! Thanks anyway!!!

Hey Szymon Z.

What you won't is to not fetch for the Article record automatically? If that's the case just change yourArticle $article argument to string $slug

Cheers!

Hey Stephansav,

So, Doctrine was not able to find the Article object. Please, make sure that an Article exist with the slug you specified in the URL. For this, you can check your article table in MySQL DB. Most probably you just have a typo in your slug

Cheers!

Hey Avraham M.

If you want to cache queries, you can use Doctrine cache to do it but I don't recommend it because you would have to purge the cache whenever your object changes and it can be very problematic. What you can do is to use the app.cache service and cache computed data. What I mean is if you want to cache the serialized version of an object, you can cache the result and probably add a TTL to it, or do whatever you need to be sure that you are not using old cached data

Cheers!

I started to use TagAWareCacheInterface cache, very interesting!
Thanks!

Hey hanen

If you already load the fixtures (or manually added some comments), you should see the comments. So, first double check the database records and if you see comments there, then maybe you are not fetching from the right repository. Double check you are injecting the CommenRepository.

Cheers!

Hi Diego
I already loaded my comments and when I use php bin/console doctrine:query:sql 'SELECT * FROM comment' it show up normally but in my controller when I fetching for comments it doesn't work

ArticleController.php on line 80:
[]
I think my problem is that I migrate comment table it produced following error ::
SQLSTATE[42S01]: Base table or view already exists: 1050 Table 'comment' already exists

And you are using the CommentRepository in your controller, right? Can you double check that you are on the dev environment? or that you loaded the fixtures for the dev environment
Another thing you can check is the profiler at the "Doctrine" tab, so you can see which queries are being executed

Thank you for your response
I think findBy method is not working but findAll returns records of comments

Ohh, the findBy() method expects a criteria, in other words, your WHERE clause, so it can filter the records. Probably you where passing something that matches nothing in your table? That's why I recommend you to inspect the executed queries via the profiler :)

Hi Diego
the doctrine connection had the access to database and in symfony profiler there are two queries that were executed

#▼ Time Info
2 1.00 ms
SELECT t0.id AS id_1, t0.author_name AS author_name_2, t0.content AS content_3, t0.created_at AS created_at_4, t0.updated_at AS updated_at_5, t0.article_id AS article_id_6 FROM comment t0 WHERE t0.article_id = ?
Parameters:
[▼
64
]
Hide formatted query Hide runnable query Explain query
SELECT
t0.id AS id_1,
t0.author_name AS author_name_2,
t0.content AS content_3,
t0.created_at AS created_at_4,
t0.updated_at AS updated_at_5,
t0.article_id AS article_id_6
FROM
comment t0
WHERE
t0.article_id = ?
SELECT t0.id AS id_1, t0.author_name AS author_name_2, t0.content AS content_3, t0.created_at AS created_at_4, t0.updated_at AS updated_at_5, t0.article_id AS article_id_6 FROM comment t0 WHERE t0.article_id = 64;
1 4.00 ms
SELECT t0.id AS id_1, t0.title AS title_2, t0.slug AS slug_3, t0.content AS content_4, t0.published_at AS published_at_5, t0.price AS price_6, t0.name AS name_7, t0.author AS author_8, t0.heart_count AS heart_count_9, t0.image_filename AS image_filename_10, t0.created_at AS created_at_11, t0.updated_at AS updated_at_12 FROM article t0 WHERE t0.slug = ? LIMIT 1
Parameters:

Hey hanen, sorry for the late reply

Your queries looks fine to me. The first one is trying to get all comments for given Article ID (64), and the second one is trying to find an Article from its slug field

If you think you have a problem with your DB, you can recreate it from scratch like this:

bin/console doctrine:database:drop --force
bin/console doctrine:database:create
bin/console doctrine:schema:create
bin/console doctrine:fixtures:load

Cheers!

Hi Diego
when I run this command php bin/console:schema:create I got this error:
Schema-Tool failed with Error 'An exception occurred while executing 'CREATE TABLE migration_versions (version VARCHAR(255) NOT NULL, PRIMARY KEY
(version)) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci ENGINE = InnoDB':
SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes' while executing DDL: CREATE TABL
E migration_versions (version VARCHAR(255) NOT NULL, PRIMARY KEY(version)) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci ENGINE = Inno
DB
SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes..
And thank you for your assistance :)))

Ohh, that's because of your MySql version, please upgrade to 5.7+ or if that's not possible you will have to limit the length of your fields to 181 characters I believe.

Hey Dominik!

You have two options for this:

1) You can add a fetch="EAGER" option to your OneToMany annotation. But that will fetch them "eager" in ALL cases.

2 Create a custom query that JOINs to the comments and fetches them. We do that here: https://symfonycasts.com/screencast/doctrine-relations/join-n-plus-one#solving-the-n-1-extra-queries-problem. Well, that is an example of starting with a Comment and joining back to an Article. You would do the opposite: start with an Article, then leftJoin over to comments.

Let me know if this helps!

Cheers!

I watch that video about join and it works. Thank you.

Hey Frank K.

I believe your DB schema is out of sync, I mean, you added a new property to your entity but didn't update the schema

php ./bin/console doctrine:schema:update --force```
 pass --dump-sql first so you can see the SQL which will be executed

Cheers!

I find it's

$article->getComments()->isEmpty()

Hey Dmitriy,

Yeah, you nailed it! That's exactly the best way to check it. The "empty($comments)" always returns false because you check that $comments variable is empty, but that's not true, it's always an object. And thanks for sharing your solution with others!

Cheers!