Consult children objects that satisfy condition in parent objects, Relationship with eloquent

Question

I have in my project two tables that relate, but I would like to make a query Consult that brings all children entities that a field is equal to parent entity, being for all parent entities that satisfy a specific condition.

Someone could help me?

I want to take all the wheels that vehicle (parent class) is red, being that vehicles is a table, wheels is another, and color (the red) is a field. Dummy example. In this case I want all wheels only.

Answer 1

Since you didn’t give a real example, I used the fictional classes Pai and Filho

$dados = Pai::with('filhos')->where('coluna', 'algum valor')->get();

In this case, it is necessary to have the relationship mapped in the model

class Pai extends Model
{
    public function filhos() {
        return $this->hasMany(Filho::class);
    }
}

---

Applying to the example of Veiculo and Roda

class Veiculo extends Model 
{
    public function rodas() {
        return $this->hasMany(Roda::class);
    }
}

The use would be

$dados = Veiculo::with('rodas')->where('cor', 'vermelho')->get();

---

To return only the daughter entities, it is possible to make a join

$dados = Roda::join('veiculos', function($query) {
    $query->on('veiculos.id', '=', 'rodas.veiculo_id');
    $query->where('veiculo.cor', '=', 'vermelho');
})
->get();

• Laravel’s documentation on relationships.
• Method documentation join().