A cycle has been detected, so a topological sort is not possible. The getCycle() method provides the list of nodes that form the cycle. #7366

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admin · 2026-01-22T15:50:43+01:00

admin commented

2026-01-22 15:50:43 +01:00

Originally created by @collmomo on GitHub (May 5, 2024).

Bug Report

Q	A
BC Break	yes/no
Version	3.1.3

Summary

The following message get thrown: "A cycle has been detected, so a topological sort is not possible. The getCycle() method provides the list of nodes that form the cycle." after removing/flushing an entity while using semantically correct doctrine syntax and sound logic

Current behavior

Blocking the flush process from removing the entity while using OneToOne relations.
More context here: Stackoverflow

How to reproduce

OneToOne relations with self using cascade:remove

class Parent {

 #[ORM\OneToMany(targetEntity: PageTemplate::class, cascade: ['persist', 'remove'])] 
    private Collection $pageTemplates;

}

class PageTemplate {

    // ====================== PREVIOUS/NEXT ================================ //

    #[ORM\OneToOne(targetEntity: self::class, cascade: ['persist', 'remove'])]
    private ?self $nextPage= null;

    #[ORM\OneToOne(targetEntity: self::class, cascade: ['persist', 'remove'])]
    private ?self $previousPage = null;`
}

$em->remove($parent);
$em->flush();

Expected behavior

Don't throw the error, there's no cycle (infinite loop?) here, just remove the entity.

I fixed the issue by adding the following attribute: #[ORM\JoinColumn(nullable: true, onDelete: 'CASCADE')]

Another solution could have been to manually clear the relations before removing the entity:

    #[ORM\PreRemove]
    public function onPreRemove(PreRemoveEventArgs $args): void {
        /* Remove any references to self, as this will throw a CycleDetectedException */
        foreach ($this->getPageTemplates() as $pageTemplate):
            $pageTemplate->setNextPage(null);
            $pageTemplate->setPreviousPage(null);
        endforeach;
    }

Originally created by @collmomo on GitHub (May 5, 2024). ### Bug Report  | Q | A |------------ | ------ | BC Break | yes/no | Version | 3.1.3 #### Summary The following message get thrown: "A cycle has been detected, so a topological sort is not possible. The getCycle() method provides the list of nodes that form the cycle." after removing/flushing an entity while using semantically correct doctrine syntax and sound logic #### Current behavior Blocking the flush process from removing the entity while using `OneToOne` relations. More context here: [Stackoverflow](https://stackoverflow.com/questions/77483935/symfony-a-cycle-has-been-detected-so-a-topological-sort-is-not-possible) #### How to reproduce OneToOne relations with `self` using `cascade:remove` ``` class Parent { #[ORM\OneToMany(targetEntity: PageTemplate::class, cascade: ['persist', 'remove'])] private Collection $pageTemplates; } class PageTemplate { // ====================== PREVIOUS/NEXT ================================ // #[ORM\OneToOne(targetEntity: self::class, cascade: ['persist', 'remove'])] private ?self $nextPage= null; #[ORM\OneToOne(targetEntity: self::class, cascade: ['persist', 'remove'])] private ?self $previousPage = null;` } $em->remove($parent); $em->flush(); ``` #### Expected behavior Don't throw the error, there's no cycle (infinite loop?) here, just remove the entity. I fixed the issue by adding the following attribute: `#[ORM\JoinColumn(nullable: true, onDelete: 'CASCADE')]` Another solution could have been to manually clear the relations before removing the entity: ``` #[ORM\PreRemove] public function onPreRemove(PreRemoveEventArgs $args): void { /* Remove any references to self, as this will throw a CycleDetectedException */ foreach ($this->getPageTemplates() as $pageTemplate): $pageTemplate->setNextPage(null); $pageTemplate->setPreviousPage(null); endforeach; } ```

admin closed this issue

2026-01-22 15:50:43 +01:00

admin referenced this issue

2026-01-22 16:07:35 +01:00

[PR #7367] Fix for BC break in 2.6.2 when calling EM::find() with LockMode::OPTIMISTIC outside of a TX #10453

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Reference: doctrine/archived-orm#7366