How to save In Pivot Table in Laravel - php

Question

How to save data to pivot table in laravel , I have two tables has many-to-many relationship , so i create pivot table , I tried the sync() method to insert but it keep gives me this exception:
"message": "Call to a member function sync() on null",
"exception": "Symfony\Component\Debug\Exception\FatalThrowableError",
here is Contract Model :
class Contract extends Model
{
public function skills(){
$this->belongsToMany(RequiredSkills::class , 'contract_skills')->withTimestamps();
}
}
and here is RequiredSkills Model :
class RequiredSkills extends Model
{
public function contract(){
$this->belongsToMany(Contract::class , 'contract_skills');
}
}
and here is the controller :
class RequiredSkillsController extends Controller
{
public function store(Request $request){
$contract = new Contract();
$data = $request->all();
$requiredSkills = RequiredSkills::create([
'contract_id'=>$data['contract_id'],
'skills_tag'=>$data['skills_tag'],
'user_id'=>auth()->guard('api')->user()->id
]);
$contract->skills()->sync($requiredSkills->id);
return $requiredSkills;
}
}
how to solve the exception ?

Answer 1

You don't have to write data to the relationship table laravel does it for you
When using the 'sync ()' function Laraval will automatically record the relationship in the "contract_skills" table.
You are not writing Contract to the database so it has no ID, so you will not be able to link
Contract and Skills need to be recorded before you can call
the sync () function will execute the following insert:
insert into [contract_skills] ([contract_id], [skill_id]) values (1, 1)
I would do the store function as follows
class RequiredSkillsController extends Controller
{
public function store(Request $request){
//Create Contract in database
$contract = Contract::create($request->contract);
//Get skills id to link with contract
$data = $request->skills;
//syncs with additional data
$contract->skills()->sync(array_column($data, 'id'), ['user_id'=>auth()->guard('api')->user()->id]);
return $contract->refresh()->skills;
}
}