数据透视表上的HasMany使用了错误的ID

Question

I have a ManyToMany relationship between Election and Party to connect parties to multiple elections.

public function parties(): BelongsToMany
{
    return $this
       ->belongsToMany(Party::class)
       ->using(ElectionParty::class)
       ->withPivot('has_no_answers', 'published', 'program_pdf', 'program', 'id');
}

On the pivot table election_party I added an auto incrementing id.

Parties can give answers to each election, for which reason I created a hasMany relationship to Answer on the pivot table, referenced by electionparty_id

class ElectionParty extends Pivot
{
  public function answers(): HasMany
  {
    return $this->hasMany(Answer::class);
  }
}

Now, to get the answers or in this case it's count, i do this in Blade:

@foreach($election->parties as $party)
    {{ $party->pivot->answers->count() }}
@endforeach

This however, does not work, because it does not try to get answers by the pivot table id, which I assumed it would be but by the id of the election:

SQLSTATE[42703]: Undefined column: 7 ERROR: column answers.election_id does not exist LINE 1: select * from "answers" where "answers"."election_id" = $1 a... ^ HINT: Perhaps you meant to reference the column "answers.question_id". (SQL: select * from "answers" where "answers"."election_id" = 16 and "answers"."election_id" is not null)

Am I missing something here or doing something not how it's supposed to be done?

Answer 1

The default keys are generated differently in pivot models. Specify the foreign key:

class ElectionParty extends Pivot
{
    public function answers(): HasMany
    {
        return $this->hasMany(Answer::class, 'electionparty_id');
    }
}