Laravel 中使用自定义主键和外键定义关联关系

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;

class CreateAccountsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('accounts', function (Blueprint $table) {
            $table->id();
            $table->string('username');
            $table->string('password');
            $table->string('nik')->nullable(); // 将 nik 字段设置为 nullable
            $table->timestamps();

            $table->foreign('nik')->references('nik')->on('students')->onDelete('cascade'); // 添加外键约束，并设置级联删除
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('accounts');
    }
}

class CreateStudentsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('students', function (Blueprint $table) {
            $table->string('nik')->primary(); // 将 nik 字段设置为主键
            $table->string('name');
            $table->string('address');
            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::dropIfExists('students');
    }
}

// Student Model (app/Models/Student.php)
namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Student extends Model
{
    use HasFactory;

    protected $primaryKey = 'nik';
    public $incrementing = false;
    protected $keyType = 'string';

    public function account()
    {
        return $this->hasOne(Account::class, 'nik', 'nik');
    }
}

// Account Model (app/Models/Account.php)
namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Account extends Model
{
    use HasFactory;

    public function student()
    {
        return $this->belongsTo(Student::class, 'nik', 'nik');
    }
}

// 获取学生的账户信息
$student = Student::find('student123'); // 假设 'student123' 是一个存在的 nik
$account = $student->account;

if ($account) {
    echo "Student Username: " . $account->username;
} else {
    echo "No account found for this student.";
}

// 获取账户的学生信息
$account = Account::find(1); // 假设 1 是一个存在的 account id
$student = $account->student;

if ($student) {
    echo "Account Owner Name: " . $student->name;
} else {
    echo "No student found for this account.";
}