Help with grandfather, father and grandson relationships

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I am learning and enjoying using the Standard, but I have some doubts about relationships and how to get the result I want.

have the tables:

TB_FORMULARIO
 - ID_FORMULARIO
 - NO_FORMULARIO

TB_CAMPO
 - ID_CAMPO
 - ID_FORMULARIO_FK
 - NO_CAMPO

TB_PREENCHIMENTO
 - ID_PREENCHIMENTO
 - ID_CAMPO_FK
 - TX_PREENCHIMENTO

And in the model classes I have the following relationships:

 class Formulario extends Model{
   ...
   public function campo(){            
     return $this->hasMany('App\Campo', 'ID_FORMULARIO_FK', 'ID_FORMULARIO');
   }
 }

 class Campo extends Model{
   ...
   public function formulario(){            
     return $this->belongsTo('App\Formulario', 'ID_FORMULARIO_FK', 'ID_FORMULARIO');
   }

   public function preenchimento(){            
     return $this->hasMany('App\Preenchimento', 'ID_CAMPO_FK', 'ID_CAMPO');
   }
 }

 class Preenchimento extends Model{
   ...
   public function campo(){            
     return $this->belongsTo('App\Campo', 'ID_CAMPO_FK', 'ID_CAMPO');
   }
 }

With this in my form controller I can access the data of the field table (which would be the fields of a form) by making a find by ID_FORMULARIO as below:

public function buscarFormularioCampos ($idFormulario){
    $formularioCampos = Formulario::find($idFormulario)->campo;
    ...
    return response()->json($formularioCampos);
}

But if I want to go one more level and bring the fills of a field from a form by your ID I get an error:

public function buscarFormularioCampoPreenchimentos ($idFormulario){
    $formularioCampoPreenchimentos = Formulario::find($idFormulario)->campo->preenchimento;
    ...
    return response()->json($formularioCampoPreenchimentos);
}

I believe that by the mapping done it would be possible to understand that from the table "grandfather" I am trying to access the table "grandson", is there any mapping error? Should I somehow map the relationship with the grandson in the grandfather model as well? I’m researching the subject but I haven’t found a more practical solution without having to go to writing of querys.

laravel relationship
  • 2

    Call Cristina Rocha, turn it into Family Affairs :P :D

  • What. the error? In case you need to access the method after the other relationship.!

  • The error is: Exception Property [fill] does not exist on this Collection instance. This access could be exemplified by?

  • The result I want is similar to the query: SELECT p.* FROM tb_preenchimento p WHERE p.id_campo_fk IN (select id_campo from tb_campo where id_formulario_fk = {$id_formulario}). But I wanted to do it directly (without having to assemble the query), just by mapping the models that would be something like the excerpt Formulario::find($idFormulario)->campo->preenchimento; , but which is not accepted by the Standard.

1 answer

1


There is the method hasManyThrough which enables you to link Form directly to Fill.

In the Form model it will be as follows:

 class Formulario extends Model{
   ...
   public function campo(){            
     return $this->hasMany('App\Campo', 'ID_FORMULARIO_FK', 'ID_FORMULARIO');
   }

   public function preenchimento(){            
     return $this->hasManyThrough('App\Preenchimento','App\Campo', 'ID_FORMULARIO_FK', 'ID_CAMPO_FK', 'ID_FORMULARIO', 'ID_CAMPO');
   }
 }

Source: https://laravel.com/docs/5.6/eloquent-relationships#has-Many-through

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