Laravel 一对一关系获取对象结果为 null

Question

移民人员表：

Schema::create('persons', function (Blueprint $table) {
        $table->id();
        $table->string("firstname");
        $table->string("lastname");
        $table->timestamps();
    });

移民护照表：

Schema::create('passports', function (Blueprint $table) {
        $table->id();
        $table->string("identifystring")->unique();
        $table->unsignedBigInteger("person_id");
        $table->timestamps();
        $table->foreign("person_id")->references("id")->on("persons")->onDelete("cascade");
    });

人员模型：

class Person extends Model
{
    use HasFactory;

    protected $table ="persons";

    protected $fillable = [
        "firstname",
        "lastname"
    ];

    public function passport() {
        $this->hasOne(\App\Models\Passport::class, "passports.person_id","persons.id");
    }
}

护照模型：

class Passport extends Model
{

use HasFactory;

    protected $table = "passports";

    protected $fillable = [
        "identifystring",
        "person_id"
    ];
}

执行代码：

$person = \App\Models\Person::findOrFail(2);
dd($person->passport());

结果为：null

Answer 1

class Person extends Model
{
    use HasFactory;

    protected $table ="persons";

    protected $fillable = [
        "firstname",
        "lastname"
    ];

    public function passport() {
        $this->hasOne(\App\Models\Passport::class, "person_id", "id");
    }
}

Answer 2

您没有返回该关系。只需返回它：

public function passport() {
    return $this->hasOne(\App\Models\Passport::class, "passports.person_id","persons.id");
}

Answer 3

根据所写的迁移。在 Person 模型中编写

  public function passport() {
        return $this->hasOne(\App\Models\Passport::class, "person_id","id");
    }

并在 Passport 模型中编写

public function person() {
    return $this->belongsTo(\App\Models\Person::class, 'id', 'person_id');
}

执行代码

$person = \App\Models\Person::findOrFail(2)->passport;
dd($person);

Answer 4

使用此代码。

在你的个人模型中

public function passport() {
        return $this->hasOne(\App\Models\Passport::class);
    }

在你的护照模型中

public function person() {
    return $this->belongsTo(\App\Models\Person::class, 'person_id');
}

然后尝试通过做同样的事情再次传递关系

$person = \App\Models\Person::findOrFail(2);
dd($person->passport());