Eloquent 关系控制器抛出试图获取非对象的属性

Question

我有两个具有一对一关系的 table（学生和 phone）。问题是 StudentController 抛出 Trying to get 属性 of non-object

这是我的代码

Phone.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Phone extends Model
{
//
protected $table = 'phone';

protected $primaryKey = 'student_id';

protected $fillable = [
    'student_id',
    'phone_number',
];

public function student()
{
    return $this->belongsTo('App\Student', 'id_student');
}
}

Student.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;




class Student extends Model
{
    protected $table = 'student';

    protected $fillable = [
        'nisn',
        'student_name',
        'date_birth',
        'sex',
    ];

    protected $dates = ['date_birth'];


    public function getStudentNameAttribute($student_name)
    {
        return ucwords($student_name);
    }


    public function setStudentNameAttribute($student_name)
    {

        $this->attributes['student_name'] = strtolower($student_name);
        //return strtolower($student_name);
    }


    public function phone() {
        return $this->hasOne('App\Phone', 'student_id');
    }      

    }

Phone迁移

<?php

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

class CreateTablePhone extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {

        Schema::create('phone', function (Blueprint $table) 
        {          
            $table->integer('student_id')->unsigned()->primary('student_id');
            $table->string('phone_number')->unique();
            $table->timestamps();

                $table->foreign('student_id')
                    ->references('id')->on('student')
                    ->onDelete('cascade')
                    ->onUpdate('cascade');
        });

    }

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

学生控制器

public function store(Request $request)
{

    $input = $request->all();

    $validator = Validator::make($input, [
        'nisn' => 'required|string|size:4|unique:student,nisn',
        'student_name' => 'required|string|max:30',
        'date_birth' => 'required|date',
        'sex' => 'required|in:M,W',
        'phone_number' => 'required|numeric|digits_between:10,15|unique:phone,phone_number',
    ]);

    if ($validator->fails()) {
        return redirect('student/create')
            ->withInput()
            ->withErrors($validator);
    }

    Student::create($input);


    $phone = new Phone;
    $phone->phone_number = $request->input('phone_number');
    $student->phone()->save($phone);

    return redirect('student');
}

public function edit($id)
{
    $student = Student::findOrFail($id);
    $student->phone_number = $student->phone->phone_number;
    return view('student.edit', compact('student'));
}

当我访问 "student/edit" 时出现错误说有 ErrorException (E_NOTICE) $student->phone_number = $student->phone->phone_number;

当我在 "student/create""Undefined variable: student"$student->phone()->save($phone);`[=18 上创建商店数据表单时=]

感谢任何帮助。

Answer 1

在您的 store 方法中，您从未定义名为 student 的变量。没有 $student = ... 或传递给名为 student 的方法的变量。在范围内不会为您神奇地创造任何东西。

您正在尝试使用一个不作为对象存在的变量 $student->...，您从未定义 $student。

在 edit 方法中你有：

$student = Student::findOrFail($id);
$student->phone_number = $student->phone->phone_number;

$student->phone 可能是 null。您必须在此处检查 null。单一关系类型将 return 模型实例或 null.

(null)->anything "Trying to get a property of a non-object"

更新：

我不确定你想要什么例子但是：

$student = Student::create(....);

现在您定义了一个名为 student 的变量，根据您的代码上下文，它将是您期望的对象。

if ($student->phone) {
    $student->phone_number = $student->phone->phone_number;
}

检查 $student->phone 是否具有 "truthy" 值（对象 return true 转换为 bool 时，null 将是 false)，如果我们有关系，我们将从中提取 phone_number。

我不确定您为什么要以这种方式添加 phone 数字，但您可以选择在模型上为该属性创建一个 'accessor'：

public function getPhoneNumberAttribute()
{
    return $this->phone ? $this->phone->phone_number : null;
    // php 7+
    return $this->phone->phone_number ?? null;
}

那种类型的东西，现在 $student->phone_number 将为您从关系中获得价值……可以调整该方法，但基本上就是这样。

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