Laravel急于加载错误“试图在... / BelongsToMany.php中获取非对象的属性”

debugcn 发表于 Dev

诺卡因

Laravel 5.8

我有一个问题，渴望在某些模型上加载而不是在其他模型上运行。

使用工匠修补匠，我可以奔跑；

$p = App\Programme::find(34)->reviews

并获得正确的结果。如果我将其更改为；

$p = App\Programme::with('reviews')->find(34)

为了使评论热切地加载，它会因错误而失败

PHP Notice:  Trying to get property of non-object in .../vendor/laravel/framework/src/Illuminate/Database/Eloquent/Relations/BelongsToMany.php on line 301

来自工匠的输出，带有查询日志，绑定和执行时间

$p = App\Programme::with('destinations', 'reviews')->find(34)

"select * from `programmes` where `programmes`.`id` = ? and `programmes`.`deleted_at` is null limit 1"
array:1 [
  0 => 34
]
1.08


"select `destinations`.*, `programme_destination`.`programme_id` as `pivot_programme_id`, `programme_destination`.`destination_id` as `pivot_destination_id`, `programme_destination`.`created_at` as `pivot_created_at`, `programme_destination`.`updated_at` as `pivot_updated_at` from `destinations` inner join `programme_destination` on `destinations`.`id` = `programme_destination`.`destination_id` where `programme_destination`.`programme_id` in (34)"
[]
0.88


"select `reviews`.*, `programme_reviews`.`programme_id` as `pivot_programme_id`, `programme_reviews`.`review_id` as `pivot_review_id`, `programme_reviews`.`created_at` as `pivot_created_at`, `programme_reviews`.`updated_at` as `pivot_updated_at` from `reviews` inner join `programme_reviews` on `reviews`.`id` = `programme_reviews`.`review_id` where `programme_reviews`.`programme_id` in (34)"
[]
0.85

如果手动运行，则最终查询可以正常工作。

我可以使用用户或目标模型运行完全相同的两个命令，并获得成功的响应。因此$programme->reviews，与$programme->user或时的关系一定有所不同$programme->destinations

这是我的模型（已修剪到相关功能）；

应用\ BaseModel

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\SoftDeletes;
use OwenIt\Auditing\Contracts\Auditable;
use Log;
use DB;

class BaseModel extends Model
{
    protected $guarded = ['alias', 'created_at', 'updated_at', 'deleted_at', 'slug'];

    public $custom_attributes = [];
    public $index_attributes = ['alias', 'user'];


    public function alias()
    {
        return $this->morphOne('App\Alias', 'aliased');
    }

    public function user()
    {
        return $this->belongsTo('App\User');
    }

}

应用程式

<?php

namespace App;

use App\BaseModel;
use Illuminate\Database\Eloquent\SoftDeletes;
use OwenIt\Auditing\Contracts\Auditable;
use Log;

class Programme extends BaseModel implements Auditable
{
    use SoftDeletes;
    use \OwenIt\Auditing\Auditable;


    protected $table = 'programmes';

    protected $dates = ['deleted_at'];


    function __construct(array $attributes = array())
    {
        parent::__construct($attributes);
    }

    public function destinations()
    {
        return $this->belongsToMany('App\Destination', 'programme_destination')
            ->withTrashed()
            ->withTimestamps();
    }

    public function reviews()
    {
        return $this->belongsToMany('App\Review', 'programme_reviews')
            ->withTrashed()
            ->withTimestamps();
    }
}

应用\评论

<?php

namespace App;

use App\BaseModel;
use Illuminate\Database\Eloquent\SoftDeletes;
use OwenIt\Auditing\Contracts\Auditable;
use Log;

class Review extends BaseModel implements Auditable
{
    use SoftDeletes;
    use \OwenIt\Auditing\Auditable;

    protected $fillable = ['title', 'name', 'first_name', 'last_name', 'review_type', 'email_address', 'created_at'];


    function __construct(array $attributes = array())
    {
        parent::__construct($attributes);
    }

    public function programmes()
    {
        return $this->belongsToMany('App\Programme', 'programme_reviews')
            ->withTrashed()
            ->withTimestamps();
    }
}

我可以$p = App\Programme::with('destinations', 'alias')->find(34)成功运行。这是目的地的模型

应用\目的地

<?php

namespace App;

use App\BaseModel;
use Illuminate\Database\Eloquent\SoftDeletes;
use OwenIt\Auditing\Contracts\Auditable;


class Destination extends BaseModel implements Auditable
{
    use SoftDeletes;
    use \OwenIt\Auditing\Auditable;


    protected $table = 'destinations';

    protected $dates = ['deleted_at'];


    function __construct(array $attributes = array())
    {
        parent::__construct($attributes);
    }

    public function programmes()
    {
        return $this->belongsToMany('App\Programme', 'programme_destination')
            ->withTrashed()
            ->withTimestamps();
    }
}

看来这种关系是基于第一个手工艺命令的，所以为什么当急切加载时这不起作用？

作为参考，这里是数据库创建代码；

程式

CREATE TABLE `programmes` (
    `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
    `name` VARCHAR(191) NOT NULL COLLATE 'utf8_unicode_ci',
    `destination_id` INT(10) UNSIGNED NULL DEFAULT NULL,
    `user_id` INT(10) UNSIGNED NOT NULL DEFAULT '1',
    `created_at` TIMESTAMP NULL DEFAULT NULL,
    `updated_at` TIMESTAMP NULL DEFAULT NULL,
    `deleted_at` TIMESTAMP NULL DEFAULT NULL,
    PRIMARY KEY (`id`),
    INDEX `programmes_user_id_foreign` (`user_id`),
    INDEX `programmes_destination_id_foreign` (`destination_id`),
    CONSTRAINT `programmes_destination_id_foreign` FOREIGN KEY (`destination_id`) REFERENCES `destinations` (`id`),
    CONSTRAINT `programmes_user_id_foreign` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`)
)
COLLATE='utf8_unicode_ci'
ENGINE=InnoDB
;

CREATE TABLE `reviews` (
    `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
    `title` VARCHAR(191) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
    `name` VARCHAR(191) NOT NULL COLLATE 'utf8_unicode_ci',
    `first_name` VARCHAR(191) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
    `last_name` VARCHAR(191) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
    `email_address` VARCHAR(191) NULL DEFAULT NULL COLLATE 'utf8_unicode_ci',
    `created_at` TIMESTAMP NULL DEFAULT NULL,
    `updated_at` TIMESTAMP NULL DEFAULT NULL,
    `deleted_at` TIMESTAMP NULL DEFAULT NULL,
    PRIMARY KEY (`id`)
)
COLLATE='utf8_unicode_ci'
ENGINE=InnoDB
;

program_reviews-多对多

CREATE TABLE `programme_reviews` (
    `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
    `programme_id` INT(10) UNSIGNED NOT NULL,
    `review_id` INT(10) UNSIGNED NOT NULL,
    `created_at` TIMESTAMP NULL DEFAULT NULL,
    `updated_at` TIMESTAMP NULL DEFAULT NULL,
    PRIMARY KEY (`id`),
    INDEX `programme_reviews_review_id_foreign` (`review_id`),
    INDEX `programme_id` (`programme_id`),
    CONSTRAINT `programme_reviews_programme_id_foreign` FOREIGN KEY (`programme_id`) REFERENCES `programmes` (`id`) ON UPDATE CASCADE ON DELETE CASCADE,
    CONSTRAINT `programme_reviews_review_id_foreign` FOREIGN KEY (`review_id`) REFERENCES `reviews` (`id`) ON UPDATE CASCADE ON DELETE CASCADE
)
COLLATE='utf8_unicode_ci'
ENGINE=InnoDB
;

目的地

CREATE TABLE `destinations` (
    `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
    `name` VARCHAR(191) NOT NULL COLLATE 'utf8_unicode_ci',
    `user_id` INT(10) UNSIGNED NOT NULL DEFAULT '1',
    `created_at` TIMESTAMP NULL DEFAULT NULL,
    `updated_at` TIMESTAMP NULL DEFAULT NULL,
    `deleted_at` TIMESTAMP NULL DEFAULT NULL,
    PRIMARY KEY (`id`),
    INDEX `destinations_parent_id_index` (`parent_id`),
    INDEX `destinations_user_id_foreign` (`user_id`),
    CONSTRAINT `destinations_user_id_foreign` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`)
)
COLLATE='utf8_unicode_ci'
ENGINE=InnoDB
;

program_destinations一对多

CREATE TABLE `programme_destination` (
    `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
    `programme_id` INT(10) UNSIGNED NOT NULL,
    `destination_id` INT(10) UNSIGNED NOT NULL,
    `created_at` TIMESTAMP NULL DEFAULT NULL,
    `updated_at` TIMESTAMP NULL DEFAULT NULL,
    PRIMARY KEY (`id`),
    INDEX `programme_destination_programme_id_foreign` (`programme_id`),
    INDEX `programme_destination_destination_id_foreign` (`destination_id`),
    CONSTRAINT `programme_destination_destination_id_foreign` FOREIGN KEY (`destination_id`) REFERENCES `destinations` (`id`) ON UPDATE CASCADE ON DELETE CASCADE,
    CONSTRAINT `programme_destination_programme_id_foreign` FOREIGN KEY (`programme_id`) REFERENCES `programmes` (`id`) ON UPDATE CASCADE ON DELETE CASCADE
)
COLLATE='utf8_unicode_ci'
ENGINE=InnoDB
;

$programme->destinations和之间唯一真正的区别$programme->reviews是reviews多对多关系。

诺卡因

因此，由于有了外部帮助，我找到了此小问题的答案。

我的问题将无法回答，因为该问题实际上与$pivot我在Program模型上分配的类变量有关（已删除，以供帖子尝试缩短）。

这个变量与Laravel的内部运作方式发生冲突，据我所知，这似乎非常明显。

更改$pivot为其他任何内容都可以正确加载该关系。

不太可能有人会遇到与我相同的问题，但谁知道，这可能会帮助某人避免我遇到的错误。

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