Call to undefined Builder::save() when saving a polymorphic relationship

问题

I'm trying to save a polymorphic relationship when registering a user, but it returns me:

Call to undefined method Illuminate\Database\Query\Builder::save()

I have 3 tables on my database:

Schema::create('usuarios', function(Blueprint $table) {
    $table->increments('id');
    $table->string('nombreUsuario', 20);
    $table->string('password', 60);
    $table->string('email', 30);
    $table->string('remember_token', 100)->nullable();
    $table->integer('cuenta_id');
    $table->string('cuenta_type');

    $table->timestamps();
});

Schema::create('empresas', function(Blueprint $table) {
    $table->increments('id');
    $table->string('nombreEmpresa', 50);
    $table->string('direccion', 50);

    $table->timestamps();
});

Schema::create('alumnos', function(Blueprint $table) {
    $table->increments('id');
    $table->string('nombre', 50);
    $table->string('apellidoPaterno', 50);
    $table->string('apellidoMaterno', 50);
    $table->integer('semestre');

       $table->timestamps();
});

On my controller, when a user is being registered:

$alumno = new Alumno;

$alumno->nombre             = Input::get('nombre');
$alumno->apellidoPaterno    = Input::get('paterno');
$alumno->apellidoMaterno    = Input::get('materno');
$alumno->semestre           = Input::get('semestre');

$alumno->save();

$usuario = new User;

$usuario->nombreUsuario     = Input::get('usuario');
$usuario->password      = Hash::make(Input::get('password'));
$usuario->email             = Input::get('email');

$usuario->cuenta()->save($alumno);  // <--Here

The models:

<?php

use Illuminate\Auth\UserInterface;
use Illuminate\Auth\Reminders\RemindableInterface;

class User extends Eloquent implements UserInterface, RemindableInterface {
 ...
    public function cuenta() {
        return $this->morphTo();
    }
}

<?php

class Alumno extends Eloquent {
    protected $fillable = [];

    public function user() {
        return $this->morphMany('User', 'cuenta');
   }    
}

<?php

class Empresa extends Eloquent {
    protected $fillable = [];

    public function user() {
        return $this->morphMany('User', 'cuenta');
    }
}

Every time i try to register someone, it returns this error.

If would be great if someone can show me what i'm doing wrong. Thanks. :)

Update

Changed the way i save the models to:

$alumno->save();
$usuario->save();
$usuario->cuenta()->save($alumno);

It returns Call to undefined method Illuminate\Database\Query\Builder::save()

Also used:

$alumno->save();
$usuario->save();
$usuario->cuenta()->associate($alumno);

It returns

Maximum function nesting level of '100' reached, aborting! 

Should i use FK?

回答1:

I think you change

$usuario->cuenta()->save($alumno);

to

$usuario->save();

Then just run your polymorphic relationship as normal afterwards.

回答2:

I did it the wrong way. (?)

Changed

$usuario->cuenta()->save($alumno);

To

$alumno->user()->save($usuario);

来源：https://stackoverflow.com/questions/23599085/call-to-undefined-buildersave-when-saving-a-polymorphic-relationship