attach（）方法不附加外键值

Question

i'm doing a project in laravel,but while trying to seed my database,i get this error seeding error seeding error

here is my company seeder company seeder

the productionline seeder production line seeder the company model

will really appreciate if someone gets me out of this snug

Answer 1

->attach() function accepts a model id as a parameter, not the object itself.

$dev->productionLine()->attach($dev_line->id);