解决Symfony异步邮件立即发送问题：基于Cron的调度策略

// src/Entity/OppEmail.php
namespace App\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass="App\Repository\OppEmailRepository")
 * @ORM\Table(name="app_opp_email")
 */
class OppEmail
{
    /**
     * @ORM\Id()
     * @ORM\GeneratedValue()
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\Person") // 假设Person是收件人实体
     * @ORM\JoinColumn(nullable=false)
     */
    private $volunteer; // 收件人志愿者

    /**
     * @ORM\Column(type="json", nullable=true)
     */
    private $opportunitiesData; // 存储与邮件内容相关的机会数据

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

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

    /**
     * @ORM\Column(type="json")
     */
    private $context; // Twig模板上下文数据

    /**
     * @ORM\Column(type="boolean")
     */
    private $sent = false; // 邮件是否已发送

    /**
     * @ORM\Column(type="datetime", nullable=true)
     */
    private $sentAt; // 发送时间

    // ... 省略所有getter和setter方法 ...

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

    public function getVolunteer(): ?Person
    {
        return $this->volunteer;
    }

    public function setVolunteer(?Person $volunteer): self
    {
        $this->volunteer = $volunteer;
        return $this;
    }

    public function getOpportunitiesData(): ?array
    {
        return $this->opportunitiesData;
    }

    public function setOpportunitiesData(?array $opportunitiesData): self
    {
        $this->opportunitiesData = $opportunitiesData;
        return $this;
    }

    public function getSubject(): ?string
    {
        return $this->subject;
    }

    public function setSubject(string $subject): self
    {
        $this->subject = $subject;
        return $this;
    }

    public function getTemplatePath(): ?string
    {
        return $this->templatePath;
    }

    public function setTemplatePath(string $templatePath): self
    {
        $this->templatePath = $templatePath;
        return $this;
    }

    public function getContext(): ?array
    {
        return $this->context;
    }

    public function setContext(array $context): self
    {
        $this->context = $context;
        return $this;
    }

    public function getSent(): ?bool
    {
        return $this->sent;
    }

    public function setSent(bool $sent): self
    {
        $this->sent = $sent;
        return $this;
    }

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

    public function setSentAt(?\DateTimeInterface $sentAt): self
    {
        $this->sentAt = $sentAt;
        return $this;
    }
}

// 示例：在OpportunityController或相关服务中
// ...
// 假设 $opportunity 和 $volunteer 已经获取
$oppEmail = new OppEmail();
$oppEmail->setVolunteer($volunteer);
$oppEmail->setOpportunitiesData(['id' => $opportunity->getId(), 'title' => $opportunity->getTitle()]);
$oppEmail->setSubject('New volunteer opportunity');
$oppEmail->setTemplatePath('Email/volunteer_opportunities.html.twig');
$oppEmail->setContext([
    'fname' => $volunteer->getFname(),
    'opportunity' => $opportunity,
]);
$oppEmail->setSent(false); // 标记为未发送
$entityManager->persist($oppEmail);
$entityManager->flush();
// ...

// src/Services/EmailerService.php
namespace App\Services;

use Doctrine\ORM\EntityManagerInterface;
use Symfony\Bridge\Twig\Mime\TemplatedEmail;
use Symfony\Component\Mailer\MailerInterface;
use App\Entity\Person; // 假设Person实体用于获取发件人信息

class EmailerService
{
    private $em;
    private $mailer;

    public function __construct(EntityManagerInterface $em, MailerInterface $mailer)
    {
        $this->em = $em;
        $this->mailer = $mailer;
    }

    /**
     * 组装并发送一封邮件
     *
     * @param array $mailParams 包含 'recipient', 'subject', 'template', 'context' 等键
     */
    public function assembleAndSendEmail(array $mailParams): void
    {
        // 获取发件人信息，例如从数据库中配置的默认发件人
        // 实际项目中可能从环境变量或配置文件获取
        $sender = $this->em->getRepository(Person::class)->findOneBy(['is