在$ user-> posts()-> create([...])期间使用mutator的laravel访问相关模型 [英] laravel access related model using mutator during $user->posts()->create([...])

问题描述

我有User和Post模型.在创建帖子时调用帖子标题的变体时，希望访问用户.类似于几年前的问题.

I have User and Post models. Would like to access the User when the mutator for the post's title is being called at the time of the post creation. Similar to a question from a few years ago.

但是我无法在帖子"标题更改器中访问用户".尝试过 $ this-> user-> id (首选).还尝试过: $ this-> user_id ， $ this-> user()-> get()-> id .

But I am unable to access the User inside the Posts title mutator. Tried $this->user->id (preferred). Also tried: $this->user_id, $this->user()->get()->id.

>>> User::first()->posts()->create(['title'=>'test '.now()])

PHP Warning:  Attempt to read property "id" on null  <<<=== when trying $this->user->id
=> App\Models\Post {#4155
     title: "test 2021-05-08 11:41:55", <<<=== title is shown before user_id
     user_id: 1,                        <<<=== but in migration user_id is defined *before* title
     updated_at: "2021-05-08 11:41:55",
     created_at: "2021-05-08 11:41:55",
     id: 1,
     user: null, <<<=== note "user" attribute is added as result of the $this->user->id
   }

当我们正在使用该用户向其添加帖子时，会认为该用户当时肯定是已知的.

Would think the user is definitely known at that time, as we're using that user to add a post to.

如果我将 user_id 设为可填充，则该代码将按预期工作(对于该代码:数组顺序很重要):

If I make the user_id fillable, then this one works as expected (for that one: the array order matters):

Post::create(['user_id'=>User::first()->id, 'title'=>'test '.now()])

但是，这没那么...雄辩.

But, that's less... eloquent.

我的配置+测试详细信息:

My config + test details:

// Post.model

    protected $fillable = [
        // 'user_id', // also tried with making user_id fillable
        'title',
    ];

    public function setTitleAttribute($value) {
        // dump($this->user_id); // null
        // dump($this->user); // null (& adds empty user property to this)
        // dump($this->user->id); // PHP Warning:  Attempt to read property "id" on null (& adds property)
        // dump($this->user()->get()); // empty collection Illuminate\Database\Eloquent\Collection
        // dump($this->user()->toSql()); // select * from "users" where "users"."id" is null

        $this->attributes['title'] = $value;
    }

    public function user() {
        return $this->belongsTo(User::class);
    }

// User.model

    public function posts() {
        return $this->hasMany(Post::class);
    }

// posts migration

        Schema::create('posts', function (Blueprint $table) {
            $table->id();
            $table->foreignId('user_id')->constrained();
            $table->string('title');
            $table->timestamps();
        });

使用mysql作为数据库.

Using mysql as DB.

推荐答案

这似乎是最安全+最干净的:使用引导事件关闭正在创建" ，该操作在更改器之后且就在数据保存到数据库之前触发.

This seems to be the safest + cleanest: use boot event closure 'creating', which is triggered after the mutators and right before data is saved to the database.

    public static function boot() {
        parent::boot();

        static::creating(function (Post $post) {
            // now we have both $post->user and $post->title
            dump($post->user->name);
            dump($post->title);
        });
    }

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