Laravel - How to delete record based on condition - laravel

Question

In my Laravel-5.8, I have these three (3) models:
Parameter
class Parameter extends Model
{
protected $table = 'parameters';
protected $primaryKey = 'id';
protected $fillable = [
'max_score',
'min_score',
'identity_id',
];
public function identity()
{
return $this->belongsTo('App\Models\Identity','identity_id');
}
}
Identity
class Identity extends Model
{
protected $table = 'identity';
protected $fillable = [
'id',
'name',
];
public function goals()
{
return $this->hasMany('App\Models\Goal');
}
public function parameter()
{
return $this->hasOne(Parameter::class, 'identity_id');
}
}
Goal
class Goal extends Model
{
protected $table = 'goals';
protected $fillable = [
'id',
'identity_id',
'title',
];
public function identity()
{
return $this->belongsTo('App\Models\Identity','identity_id');
}
}
From the model, Identity has a foreign key (identity_id) in Parameter, also Identity has foreign key (identity_id) in Goal.
I have this controller in Identity:
public function destroy($id)
{
try
{
$identity = Identity::findOrFail($id);
$identity->delete();
Session::flash('success', 'Record deleted successfully.');
return redirect()->back();
}
catch (Exception $exception) {
Session::flash('error', 'Record delete failed!.');
return redirect()->back();
}
}
I want the user to delete Identity Record based on these conditions:
As the user tries to delete Identity, the application should check Parameter table and also delete the record where identity_id foreign key exist.
Secondly, if record with identity_id exists in Goal table, the application should prevent the delete.
How do I adjust public function destroy($id) to achieve this?

Answer 1

you can add a function like "deleteAll()" in your 'Identify' Model and delete parameter using relation like this:
class Identity extends Model
{
protected $table = 'identity';
protected $fillable = [
'id',
'name',
];
public function goals()
{
return $this->hasMany('App\Models\Goal');
}
public function parameter()
{
return $this->hasOne(Parameter::class, 'identity_id');
}
public function deleteAll(){
if(!$this->goals){
$this->parameter->delete();
return parent::delete();
}
return;
}
}

Answer 2

First in your migrations in the identity you need to do like
$table->foreign('identity_id')->references('id')->on('parameters')->onDelete('cascade');
So when you delete the Identity the related Parameter will be deleted automatically on database level.
To prevent delete (your mentioned 2 case), you need to check like this
$identity = Identity::with('goals')->findOrFail($id);
if($identity->goals){
// you can throw some error here
}