why laravel belongsToMany update extra pivot column

Question

data:

id  modelable_type  modelable_id    category_id slug
7   Modules\Admin\Entities\AdminModel   10  1   admin
8   Modules\Admin\Entities\AdminModel   10  2   admin2

and code is :

//sync method:
$admin->categoriesRelation()->sync([1 => ['slug' => 'admin'], 2 => ['slug' => 'admin2']]);

admin relation:

//relation :
public function categoriesRelation(): belongsToMany {
        return $this->belongsToMany(CategoryModel::class, 'category_relations', 'modelable_id', 'category_id')->withPivot('slug')->withPivotValue('modelable_type', static::class);
}

queries:

select * from `category_relations` 
where `modelable_type` = 'Modules\Admin\Entities\AdminModel'
    and `category_relations`.`modelable_id` = 10

update `category_relations` 
set `slug` = 'admin' 
where `modelable_type` = 'Modules\Admin\Entities\AdminModel'
    and `category_relations`.`modelable_id` = 10 and `category_id` in (1)

update `category_relations` 
set `slug` = 'admin2' 
where `modelable_type` = 'Modules\Admin\Entities\AdminModel'
    and `category_relations`.`modelable_id` = 10 and `category_id` in (2)

relation sync without any data change, All records are updated again.

Please post your data and queries as text within the question. See https://meta.stackoverflow.com/questions/285551/why-should-i-not-upload-images-of-code-data-errors — Calum Halpin, Dec 31 '22 at 02:39

score 0 · Answer 1 · answered Dec 31 '22 at 04:59

0

The sync method will remove any existing records in the pivot table that are not part of update array, and then insert the two records you specified.

If you do not want to update the existing records in the pivot table, you can use the attach method instead.

answered Dec 31 '22 at 04:59

Ali Raza

842
7
13

i use sync method to automatic attach/detach relation. – Masoud derakhsh Dec 31 '22 at 05:15
Were you successful? – Ali Raza Dec 31 '22 at 05:16
sync method will not remove exist record in array argument, but why eloquent update them without any change. – Masoud derakhsh Dec 31 '22 at 05:20
they are deleted and then recreated w/o any change; of course the IDS will auto increment – Ali Raza Dec 31 '22 at 05:21
i check eloquent sync method. Records are not created or deleted simultaneously, but are compared, New relationships are created and redundant relationships are removed, But when the data is the same, why are the columns being updated again for no reason? – Masoud derakhsh Dec 31 '22 at 05:28
see the accepted answer here: might help => https://stackoverflow.com/questions/23968415/laravel-eloquent-attach-vs-sync – Ali Raza Dec 31 '22 at 05:31
this relation has extra data in pivot table. And the problem of additional updates is on the same data ( ['slug' => 'admin'] ) – Masoud derakhsh Dec 31 '22 at 05:34

why laravel belongsToMany update extra pivot column

1 Answers1