Symfony3 Doctrine2 Column cannot be null - sql

Question

[PROBLEM SOLVED]
Hey folks I need your help on a symfony project.
I have two entities, "article" and "image", article can have several images so I made a relationship OneToMany on the article side and ManyToOne on the image side. Doctrine generates for me an "article_id" column on the image table.
I made a form to create an article with one or more images... however when I execute it I have an error that is thrown :
An exception occurred while executing 'INSERT INTO image (url, alt, article_id) VALUES (?,?,?) 'with params ["jpeg", "untitled.jpg", null]: SQLSTATE [23000]: Integrity constraint violation: 1048 Column' article_id 'can not be null.
When I look to the profiler logs debug, I can see that I have an "INSERT INTO article[...]" (so the article is created with an ID ?) and just after this I have the famous "INSERT INTO image[...]" where the error occurs.
Thank you for your help.
EDIT In bold you will find the lines I added to solve this problem.
I added into the ArticleType form, in the images collection options this :
'by_reference' => false
And I added to the addImage method into the Article entity this :
$image->setArticle($this);
$this->images->add($image);

Answer 1

This is a very common question but surprisingly difficult to search for. In fact the first ten or so search results had incorrect answers.
In any event, you need to make sure that image is linked to the article.
class Article
public function addImage($image) {
$this->images[] = $image;
$image->setArticle($this); // ADD THIS

Answer 2

I think #Cerad's answer is very wrong, although I can't blame him because OP hasn't posted enough code, don't be shy with it, we're here to help. It also helps to briefly mention if you're just starting out (as I suspect you are) as it will help us gauge whether its a novice problem or something deeper.
Since I'm assuming it's a novice problem here is the novice solution.
With they way you've mapped (which I believe is correct) you are basically telling Doctrine to Tell your RDBMS (MySql/MariaDB/PostgreSQL) that an article CAN have many images, but an image MUST belong to an article.
This means that if you attempt to save an image without specifying the owning article, it will throw an error.
This is what I think you are doing evident in the line
(url, alt, article_id) VALUES (?,?,?) 'with params ["jpeg", "untitled.jpg", null]
the value "null" is where the issue is coming about because you are not specifying the owning article.
You have 2 options
1.) When saving image, if you have the article object at hand just do
$image->setArticle($article);
2.) When saving the image, if you have the article_id at hand just do
$image->setArticle($em->getReference('AppBundle\Entity\Articles', $article_id));
You must follow one of the above when saving an image directly.
My general experience has been that Doctrine does a really good job of generating entities from command line that you really don't need to change much unless adding some advanced functionality like second_level_cache or MySQL point type.
Cheers.

Answer 3

The problem is that when you submit your form, the first image is attached to the article but the others are not, so you get an SQL error.
You have to do a "foreach loop" for every image and attched the article to each one.
Look here at the addAction function
https://github.com/ismail1432/TheGoodLoc/blob/master/Symfony/src/VTC/AnnonceBundle/Controller/AdvertController.php