我需要在树枝 Symfony 中检索用户

Question

My Blog
在这里，我在 Twig 中检索用户的代码有点问题，我在文章 table 和用户 table 之间有一个 ManyToOne 关系 ，我想检索文章的作者，但我做不到。在数据库中一切都很好，但在 Twig 中我不知道该怎么做。
星期一代码

ArticleController.php

/**
     * @Route("/add-article", name="add_article", methods={"GET","POST"})
     */
    public function new(Request $request): Response
    {

        $article = new Article();
        $form = $this->createForm(ArticleFormType::class, $article);
        $form->handleRequest($request);

        if ($form->isSubmitted() && $form->isValid())
         {

            $article->setUsers($this->getUser());
            $entityManager = $this->getDoctrine()->getManager();
            $entityManager->persist($article);
            $entityManager->flush();

            return $this->redirectToRoute('blog_articles');
        }

        return $this->render('articles/Article-form.html.twig', [            
            'form_title'=> 'Ajouter un Article',
            'form_article' => $form->createView(),
        ]);
    }

我的树枝

{% for  article in articles %}
        <div class="col-md-6 col-lg-4">
            <div class="card mb-4 shadow-sm">
                <!-- CONDITIONS POUR L'AFFICHAGE DES PHOTOS-->
                {% if article.photo is defined and article.photo is not null %}
                <img src="{{asset('images/')}}{{ article.photo }}" class="img-fluid" width="100%" height="225">
                {% else %}
                <img src="{{asset('images/img-17.jpg')}}" class="img-fluid" width="100%" height="225">
                {% endif %}
                <div class="card-body">
                    <!--BOUCLE POUR RECUPERER LE CATEGORIE DE CHAQUE ARTICLE-->
                    {% for categorie in article.categories %}
                    <span class="text-left" style="color: grey;">{{ categorie.nom }}</span>
                    {% endfor %}
                    <!-- FIN DE LA BOUCLE-->
                    <h4 class="text-center titre">
                        <a href="{{ path('blog_article', {'id': article.id}) }}"> {{ article.titre }} </a>
                    </h4>
                    <p class="card-text">{{ article.description }}</p>

                    <div class="d-flex justify-content-between align-items-center">
                        <!-- Post Author -->

                        <p class="text-muted">{{ article.users.nom }} - {{ article.createdAt| date('d/m/Y')}}</p>

                        <div class="social">
                            <ul class="list-inline">
                                <a href="" class="mr-4"><i class="fa fa-heart" aria-hidden="true"></i> 3 </a>
                                <a href=""><i class="fas fa-comments" aria-hidden="true"></i> 5 </a>
                            </ul>
                        </div>
                    </div>
                </div>
            </div>
        </div>
        {% endfor %}
        <!-- FIN DE LA BOUCLE POUR LES ARTICLES-->

我得到了什么

Impossible to access an attribute ("nom") on a null variable.

Article.php

<?php

namespace App\Entity;

use App\Repository\ArticleRepository;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass=ArticleRepository::class)
 */
class Article
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\Column(type="string", length=50)
     */
    private $titre;

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $description;

    /**
     * @ORM\Column(type="text")
     */
    private $contenu;

    /**
     * @ORM\Column(type="string", length=255, nullable=true)
     */
    private $photo;
    

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $slug;

    /**
     * @ORM\Column(type="datetime")
     */
    private $created_at;

    /**
     * @ORM\Column(type="datetime", nullable=true)
     */
    private $updated_at;

    /**
     * @ORM\OneToMany(targetEntity=Commentaire::class, mappedBy="articles", orphanRemoval=true)
     */
    private $commentaires;

    /**
     * @ORM\ManyToMany(targetEntity=Categorie::class, inversedBy="articles")
     */
    private $categories;

    /**
     * @ORM\ManyToOne(targetEntity=User::class, inversedBy="articles")
     */
    private $users;

    public function __construct()
    {
        $this->commentaires = new ArrayCollection();
        $this->categories = new ArrayCollection();
        $this->created_at= new \DateTime('now');
    }

    public function getId(): ?int
    {
        return $this->id;
    }

    public function getTitre(): ?string
    {
        return $this->titre;
    }

    public function setTitre(string $titre): self
    {
        $this->titre = $titre;

        return $this;
    }

    public function getDescription(): ?string
    {
        return $this->description;
    }

    public function setDescription(string $description): self
    {
        $this->description = $description;

        return $this;
    }

    public function getContenu(): ?string
    {
        return $this->contenu;
    }

    public function setContenu(string $contenu): self
    {
        $this->contenu = $contenu;

        return $this;
    }

    public function getPhoto(): ?string
    {
        return $this->photo;
    }

    public function setPhoto(?string $photo): self
    {
        $this->photo = $photo;

        return $this;
    }

    public function getSlug(): ?string
    {
        return $this->slug;
    }

    public function setSlug(string $slug): self
    {
        $this->slug = $slug;

        return $this;
    }

    public function getCreatedAt(): ?\DateTimeInterface
    {
        return $this->created_at;
    }

    public function setCreatedAt(\DateTimeInterface $created_at): self
    {
        $this->created_at = $created_at;

        return $this;
    }

    public function getUpdatedAt(): ?\DateTimeInterface
    {
        return $this->updated_at;
    }

    public function setUpdatedAt(?\DateTimeInterface $updated_at): self
    {
        $this->updated_at = $updated_at;

        return $this;
    }

    /**
     * @return Collection|Commentaire[]
     */
    public function getCommentaires(): Collection
    {
        return $this->commentaires;
    }

    public function addCommentaire(Commentaire $commentaire): self
    {
        if (!$this->commentaires->contains($commentaire)) {
            $this->commentaires[] = $commentaire;
            $commentaire->setArticles($this);
        }

        return $this;
    }

    public function removeCommentaire(Commentaire $commentaire): self
    {
        if ($this->commentaires->removeElement($commentaire)) {
            // set the owning side to null (unless already changed)
            if ($commentaire->getArticles() === $this) {
                $commentaire->setArticles(null);
            }
        }

        return $this;
    }

    /**
     * @return Collection|categorie[]
     */
    public function getCategories(): Collection
    {
        return $this->categories;
    }

    public function addCategory(categorie $category): self
    {
        if (!$this->categories->contains($category)) {
            $this->categories[] = $category;
        }

        return $this;
    }

    public function removeCategory(categorie $category): self
    {
        $this->categories->removeElement($category);

        return $this;
    }

    public function getUsers(): ?user
    {
        return $this->users;
    }

    public function setUsers(?user $users): self
    {
        $this->users = $users;

        return $this;
    }
}

User.php

<?php

namespace App\Entity;

use App\Repository\UserRepository;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;
use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;
use Symfony\Component\Security\Core\User\UserInterface;

/**
 * @ORM\Entity(repositoryClass=UserRepository::class)
 * @UniqueEntity(fields={"email"}, message="There is already an account with this email")
 */
class User implements UserInterface
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\Column(type="string", length=180, unique=true)
     */
    private $email;

    /**
     * @ORM\Column(type="json")
     */
    private $roles = [];

    /**
     * @var string The hashed password
     * @ORM\Column(type="string")
     */
    private $password;

    /**
     * @ORM\Column(type="boolean")
     */
    private $isVerified = false;

    /**
     * @ORM\Column(type="string", length=50)
     */
    private $nom;

    /**
     * @ORM\Column(type="string", length=50)
     */
    private $prenom;

    /**
     * @ORM\OneToMany(targetEntity=Article::class, mappedBy="users")
     */
    private $articles;

    /**
     * @ORM\OneToMany(targetEntity=Commentaire::class, mappedBy="users", orphanRemoval=true)
     */
    private $commentaires;

    public function __construct()
    {
        $this->articles = new ArrayCollection();
        $this->commentaires = new ArrayCollection();
    }

    public function __toString()
    {
        return $this->prenom . ' ' . $this->nom; 
    }


    public function getId(): ?int
    {
        return $this->id;
    }

    public function getEmail(): ?string
    {
        return $this->email;
    }

    public function setEmail(string $email): self
    {
        $this->email = $email;

        return $this;
    }

    /**
     * A visual identifier that represents this user.
     *
     * @see UserInterface
     */
    public function getUsername(): string
    {
        return (string) $this->email;
    }

    /**
     * @see UserInterface
     */
    public function getRoles(): array
    {
        $roles = $this->roles;
        // guarantee every user at least has ROLE_USER
        $roles[] = 'ROLE_USER';

        return array_unique($roles);
    }

    public function setRoles(array $roles): self
    {
        $this->roles = $roles;

        return $this;
    }

    /**
     * @see UserInterface
     */
    public function getPassword(): string
    {
        return (string) $this->password;
    }

    public function setPassword(string $password): self
    {
        $this->password = $password;

        return $this;
    }

    /**
     * @see UserInterface
     */
    public function getSalt()
    {
        // not needed when using the "bcrypt" algorithm in security.yaml
    }

    /**
     * @see UserInterface
     */
    public function eraseCredentials()
    {
        // If you store any temporary, sensitive data on the user, clear it here
        // $this->plainPassword = null;
    }

    public function isVerified(): bool
    {
        return $this->isVerified;
    }

    public function setIsVerified(bool $isVerified): self
    {
        $this->isVerified = $isVerified;

        return $this;
    }

    public function getNom(): ?string
    {
        return $this->nom;
    }

    public function setNom(string $nom): self
    {
        $this->nom = $nom;

        return $this;
    }

    public function getPrenom(): ?string
    {
        return $this->prenom;
    }

    public function setPrenom(string $prenom): self
    {
        $this->prenom = $prenom;

        return $this;
    }

    /**
     * @return Collection|Article[]
     */
    public function getArticles(): Collection
    {
        return $this->articles;
    }

    public function addArticle(Article $article): self
    {
        if (!$this->articles->contains($article)) {
            $this->articles[] = $article;
            $article->setUsers($this);
        }

        return $this;
    }

    public function removeArticle(Article $article): self
    {
        if ($this->articles->removeElement($article)) {
            // set the owning side to null (unless already changed)
            if ($article->getUsers() === $this) {
                $article->setUsers(null);
            }
        }

        return $this;
    }

    /**
     * @return Collection|Commentaire[]
     */
    public function getCommentaires(): Collection
    {
        return $this->commentaires;
    }

    public function addCommentaire(Commentaire $commentaire): self
    {
        if (!$this->commentaires->contains($commentaire)) {
            $this->commentaires[] = $commentaire;
            $commentaire->setUsers($this);
        }

        return $this;
    }

    public function removeCommentaire(Commentaire $commentaire): self
    {
        if ($this->commentaires->removeElement($commentaire)) {
            // set the owning side to null (unless already changed)
            if ($commentaire->getUsers() === $this) {
                $commentaire->setUsers(null);
            }
        }

        return $this;
    }
}

PhpMyAdmin
是一篇文章，user_Id 1.很好，数据库里有我需要的所有信息。我的问题是我无法显示文章作者的姓名。
对不起，我的英语不完美。

Answer 1

错误消息说文章的用户属性为空，这导致我们在 ORM 映射中出错，因为您说文章的数据库字段 user_id 具有正确的值 (1).

这意味着错误可能在用户上方的注释中属性。通过查看您的代码，引起我注意的一件事是指向 targetEntity 时的语法。您正在使用 User::class，但根据学说文档，它应该像这样 targetEntity="User" 或像这样 targetEntity="App\Entity\User"

    /**
     * @ORM\ManyToOne(targetEntity=User::class, inversedBy="articles")
     */
    private $users;

https://www.doctrine-project.org/projects/doctrine-orm/en/2.7/reference/association-mapping.html

我可能错了，学说可能接受所有这些语法，但我认为值得检查这一点

EDIT- 由于问题不是上述问题，要检查的另一件事是填充 Article 对象的方式。我认为您必须像这样使用 getData() 方法：

    $form = $this->createForm(ArticleType::class);

    $form->handleRequest($request);

    if ($form->isSubmitted() && $form->isValid()) {
        // new article object come back populated by the form
        $article = $form->getData();

        // record the new article
        $em = $this->getDoctrine()->getManager();
        $em->persist($article);
        $em->flush();
    }

Answer 2

代码是完美的，我遇到的唯一问题是一些文章在连接之前已经创建，因此用户在数据库中为空并且无法显示它。我删除了这些文章，问题已经解决

我需要在树枝 Symfony 中检索用户

I need to retrieve user in twig Symfony

symfony

twig

symfony4