Does Eloquent relation sync also remove?

Question

When updating a model and I sync a relationship, if I don't pass in all the ids that already exist, will that relationship be removed?

Answer 1

You decide: sync has 2nd parameter that defaults to true and is responsible for detaching:

$model->relationship()->sync([1,2,3]);

$model->relationship()->sync([4,5,6]); // attached [4,5,6], detached [1,2,3]
$model->relationship()->getRelatedIds(); // [4,5,6]

// but:
$model->relationship()->sync([4,5,6], false); // attached [4,5,6], detached []
$model->relationship()->getRelatedIds(); // [1,2,3,4,5,6]