CODEWITHSUNDEEP
performancesymfonydoctrine
wawa
wawa

Reputation: 5066

efficient way to display subset of Doctrine collection in twig

I've got a Symfony entity, which has a OneToMany mapping with an OrderBy clause like this:

/**
 * @ORM\OneToMany(targetEntity="App\Entity\News", mappedBy="category", orphanRemoval=true)
 * @ORM\OrderBy({"id" = "DESC"})
 */
private $news;

Assuming I would like to only display n entries in Twig, I would have the options to either loop over it and ignoring every thing after loop.index n or rather use slice. However these options do have the downside, that if there are a lot of news entries, all of them will be loaded, which isn't very efficient.

Another option would be to use a Criteria in the controller or the entity to limit the amount of loaded entities. If I understood it here correctly, it should modify the doctrine query directly and thus not have any performance impact. Is this the best practice, or would it be better to have a custom query builder in the controller or a function in the repository?

Upvotes: 1

Views: 336

Answers (1)

DrKey
DrKey

Reputation: 3495

Actually you can set $news relationship as EXTRA_LAZY and use $news->slice() function without triggering a full load as stated in official documentation:

If you mark an association as extra lazy the following methods on collections can be called without triggering a full load of the collection:

Collection#contains($entity)
Collection#containsKey($key) (available with Doctrine 2.5)
Collection#count()
Collection#get($key) (available with Doctrine 2.4)
Collection#slice($offset, $length = null)

Therefore your declaration should look like the following:

/**
 * @ORM\OneToMany(targetEntity="App\Entity\News", mappedBy="category", orphanRemoval=true, fetch="EXTRA_LAZY")
 * @ORM\OrderBy({"id" = "DESC"})
 */
private $news;

Upvotes: 1

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