Laravel 有许多多对多对一雄辩

我没有太多运气以 Laravel 的方式解决这个问题。所以我提出两个问题。

假设我有一辆汽车，并且该汽车可以有许多特征，但该特征也按特征类型分隔，我如何返回所述汽车的所有特征，分隔特征类型？

我有四个表，listings_features 是数据透视表：

• 列表（ID）
• 清单_功能（清单_id，功能_id）
• Listings_features_types（id，类型）
• listings_features_values（id，listing_feature_type_id，值）

我有以下代码，它生成我需要的内容，但是当我使用它时，我收到 Laravel 错误...“调用字符串上的成员函数 addEagerConstraints()”...因为我这样调用它：

Listing::with(
        'features',
    )->get();

我用来以我想要的格式（不坚定）生成数据的代码是

public function features()
{
    $out = array();
    $features = $this->hasMany('App\Models\ListingFeature', 'listing_id', 'id')->select('feature_id')->get();
    $types = ListingFeatureType::all();
    foreach($types as $key => $obj){
        $out[$key]['listing_feature_type_id'] = $obj->id;
        $out[$key]['name'] = $obj->listing_feature_type;
        $out[$key]['features'] = ListingFeatureValue::whereIn('id', $features->toArray())->where('listing_feature_type_id', '=', $obj->id)->get()->toArray();
    }
    return json_encode($out);
}

返回：

[
  {
    "listing_feature_type_id": "0f40888c-3b09-40ed-aef6-0fddc1a155b6",
    "name": "Safety",
    "features": [
      {
        "id": "0ed0ad63-a6ed-4818-8c6f-ee048694dcd9",
        "listing_feature_type_id": "0f40888c-3b09-40ed-aef6-0fddc1a155b6",
        "listing_feature_text": "Anti-Lock Brakes"
      },
      {
        "id": "37abeef2-dc22-4995-8503-f89962242ea6",
        "listing_feature_type_id": "0f40888c-3b09-40ed-aef6-0fddc1a155b6",
        "listing_feature_text": "Collision Detection"
      },
      {
        "id": "3c0728e1-91f7-4f44-ac0b-429eda816692",
        "listing_feature_type_id": "0f40888c-3b09-40ed-aef6-0fddc1a155b6",
        "listing_feature_text": "Dual Airbags"
      },
      {
        "id": "4255b8b4-e71c-4059-8a22-1b9894512564",
        "listing_feature_type_id": "0f40888c-3b09-40ed-aef6-0fddc1a155b6",
        "listing_feature_text": "Side Airbags"
      }
    ]
  },
  {
    "listing_feature_type_id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
    "name": "Interior",
    "features": [
      {
        "id": "1b89581e-1a30-4dce-9455-ab0ad4c49bcf",
        "listing_feature_type_id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
        "listing_feature_text": "Privacy Glass"
      },
      {
        "id": "59e3628f-3cef-4447-9cb2-71be4a3046a4",
        "listing_feature_type_id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
        "listing_feature_text": "Onboard GPS"
      },
      {
        "id": "66fe416b-98dc-45c8-979d-78f2ea7fe876",
        "listing_feature_type_id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
        "listing_feature_text": "In-dash Navigation"
      },
      {
        "id": "8fe836a3-5596-4306-aac1-bae4cb596e20",
        "listing_feature_type_id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
        "listing_feature_text": "Power Windows"
      },
      {
        "id": "e4addb5a-1b26-4ae3-b0ee-3b8bce892fb9",
        "listing_feature_type_id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
        "listing_feature_text": "Tinted Windows"
      },
      {
        "id": "f95b8253-a2b8-4bfc-90c0-0fc656c3f200",
        "listing_feature_type_id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
        "listing_feature_text": "CD Player"
      }
    ]
  },
  {
    "listing_feature_type_id": "8d16e8ea-3d38-48dc-8e56-00d1cc736f0d",
    "name": "Exterior",
    "features": [
      {
        "id": "3aa6dd05-dd3a-4e93-ad06-295687a8dda1",
        "listing_feature_type_id": "8d16e8ea-3d38-48dc-8e56-00d1cc736f0d",
        "listing_feature_text": "Spoiler"
      }
    ]
  }
]

以下是模型（非常基本，刚刚开始）：

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class ListingFeatureValue extends Model
{

    protected $table = 'listings_features_values';
    public $timestamps = false;
    public $incrementing = false;

    public function type() {
        return $this->belongsTo('App\Models\ListingFeatureType', 'listing_feature_type_id', 'id');
    }

}

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class ListingFeatureType extends Model
{

    protected $table = 'listings_features_types';
    public $timestamps = false;
    public $incrementing = false;

    public function values() {
        return $this->hasMany('App\Models\ListingFeatureValue', 'listing_feature_type_id', 'id');
    }

}

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class ListingFeature extends Model
{

    protected $table = 'listings_features';
    public $timestamps = false;
    public $incrementing = false;

}

如何创建 Laravel 模型关系来实现相同的结果集，但如上所述调用它？或者，我怎样才能像上面那样调用它但阻止错误发生？

如果您做到了这一点，谢谢！

Update:

我无法让它按原样工作，我收到了一个 SQL 错误，这让我觉得我需要一个belongsToManyThrough，这样我就可以指定表名称：

SQLSTATE[42S02]: Base table or view not found: 1146 Table 'ad_l5.listing_listing_feature' doesn't exist (SQL: select `listings_features`.*, `listing_listing_feature`.`listing_id` as `pivot_listing_id`, `listing_listing_feature`.`listing_feature_id` as `pivot_listing_feature_id` from `listings_features` inner join `listing_listing_feature` on `listings_features`.`id` = `listing_listing_feature`.`listing_feature_id` where `listing_listing_feature`.`listing_id` in (b266c874-1cef-4f49-b65f-f91ddaaf6aee, e93674ca-3f82-45d8-9961-e8569cac164b))

但是使用@Carter Fort 发布的确切代码作为下面的答案，并将 features() 方法更改为

return $this->belongsToMany(ListingFeatureValue::class, 'listings_features', 'listing_id', 'feature_id');

还添加到模型 ListingFeatureValue

public function type()
    {
        return $this->belongsTo(ListingFeatureType::class, 'listing_feature_type_id', 'id');
    }

我得到的输出：

"featuresByType": {
"": [
{
"id": "3aa6dd05-dd3a-4e93-ad06-295687a8dda1",
"listing_feature_type_id": "8d16e8ea-3d38-48dc-8e56-00d1cc736f0d",
"listing_feature_text": "Spoiler",
"pivot": {
"listing_id": "e93674ca-3f82-45d8-9961-e8569cac164b",
"feature_id": "3aa6dd05-dd3a-4e93-ad06-295687a8dda1"
},
"type": {
"id": "8d16e8ea-3d38-48dc-8e56-00d1cc736f0d",
"listing_feature_type": "Exterior"
}
},
{
"id": "f95b8253-a2b8-4bfc-90c0-0fc656c3f200",
"listing_feature_type_id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
"listing_feature_text": "CD Player",
"pivot": {
"listing_id": "e93674ca-3f82-45d8-9961-e8569cac164b",
"feature_id": "f95b8253-a2b8-4bfc-90c0-0fc656c3f200"
},
"type": {
"id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
"listing_feature_type": "Interior"
}
},
{
"id": "66fe416b-98dc-45c8-979d-78f2ea7fe876",
"listing_feature_type_id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
"listing_feature_text": "In-dash Navigation",
"pivot": {
"listing_id": "e93674ca-3f82-45d8-9961-e8569cac164b",
"feature_id": "66fe416b-98dc-45c8-979d-78f2ea7fe876"
},
"type": {
"id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
"listing_feature_type": "Interior"
}
},
{
"id": "0ed0ad63-a6ed-4818-8c6f-ee048694dcd9",
"listing_feature_type_id": "0f40888c-3b09-40ed-aef6-0fddc1a155b6",
"listing_feature_text": "Anti-Lock Brakes",
"pivot": {
"listing_id": "e93674ca-3f82-45d8-9961-e8569cac164b",
"feature_id": "0ed0ad63-a6ed-4818-8c6f-ee048694dcd9"
},
"type": {
"id": "0f40888c-3b09-40ed-aef6-0fddc1a155b6",
"listing_feature_type": "Safety"
}
},
  ...

这比我当时的情况要好，但如果结果按类型分组，然后按其中的功能分组，而不是每个功能都附加一个类型，那就太好了。使得解析显示变得更加困难。感谢迄今为止的帮助！

Update 2

这些将是我的架构文件：

// listings
Schema::create('listings', function (Blueprint $table) {
    $table->string('id');
    $table->string('title');
});

// listings to features pivot
Schema::create('listings_features', function (Blueprint $table) {
    $table->string('listing_id');
    $table->string('feature_id');
});

// feature types (i.e. Safety)
Schema::create('listings_features_types', function(Blueprint $table){
    $table->string('id');
    $table->string('listing_feature_type');
});

// feature values (i.e. Anti-Lock Brakes)
Schema::create('listings_features_values', function(Blueprint $table){
    $table->string('id');
    $table->string('listing_feature_type_id'); // links to listings_features_types
    $table->string('listing_feature_text');
});

Update 3根据下面的答案进行更改（一旦工作，我将发布所有代码）我接近我想要的。

"features": [
{
"id": "3aa6dd05-dd3a-4e93-ad06-295687a8dda1",
"listing_feature_type_id": "8d16e8ea-3d38-48dc-8e56-00d1cc736f0d",
"listing_feature_text": "Spoiler",
"pivot": {
"listing_id": "e93674ca-3f82-45d8-9961-e8569cac164b",
"feature_id": "3aa6dd05-dd3a-4e93-ad06-295687a8dda1"
},
"type": {
"id": "8d16e8ea-3d38-48dc-8e56-00d1cc736f0d",
"listing_feature_type": "Exterior"
}
},
{
"id": "f95b8253-a2b8-4bfc-90c0-0fc656c3f200",
"listing_feature_type_id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
"listing_feature_text": "CD Player",
"pivot": {
"listing_id": "e93674ca-3f82-45d8-9961-e8569cac164b",
"feature_id": "f95b8253-a2b8-4bfc-90c0-0fc656c3f200"
},
"type": {
"id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
"listing_feature_type": "Interior"
}
},
{
"id": "66fe416b-98dc-45c8-979d-78f2ea7fe876",
"listing_feature_type_id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
"listing_feature_text": "In-dash Navigation",
"pivot": {
"listing_id": "e93674ca-3f82-45d8-9961-e8569cac164b",
"feature_id": "66fe416b-98dc-45c8-979d-78f2ea7fe876"
},
"type": {
"id": "84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
"listing_feature_type": "Interior"
}

// .... ]

我想要的是：

{
   "feature_types":[
      {
         "type":{
            "id":"8d16e8ea-3d38-48dc-8e56-00d1cc736f0d",
            "listing_feature_type":"Interior",
            "features":[
               {
                  "id":"3aa6dd05-dd3a-4e93-ad06-295687a8dda1",
                  "listing_feature_type_id":"8d16e8ea-3d38-48dc-8e56-00d1cc736f0d",
                  "listing_feature_text":"GPS"
               },
               {
                  "id":"66fe416b-98dc-45c8-979d-78f2ea7fe876",
                  "listing_feature_type_id":"84dcce5c-34b9-4c8b-9066-5b20a42cf4cd",
                  "listing_feature_text":"In-dash Navigation"
               },

            ]            "pivot":{
               "listing_id":"e93674ca-3f82-45d8-9961-e8569cac164b",
               "feature_id":"f95b8253-a2b8-4bfc-90c0-0fc656c3f200"
            }
         }
      }
   ]
}

您可以在之间使用多对多关系Listing和ListingFeatureValue模型，然后使用给定列表按其类型对相关列表功能进行分组groupBy采集方法。

The Listing model:

class Listing extends Model {

    protected $hidden = [
        'features'
    ];

    protected $appends = [
        'feature_types'
    ];

    public function features(){
        return $this->belongsToMany(ListingFeatureValue::class, 'listings_features', 'listing_id', 'feature_id');
    }

    public function getFeatureTypesAttribute()
    {
        return $this->features->groupBy(function ($feature, $key) {
            return $feature->type->id;
        })->map(function($features, $key){
            $type = ListingFeatureType::find($key);
            $type->features = $features;
            return $type;
        })->values();
    }

}

The getFeatureTypesAttribute()是这里的明星，因为你可以将其与appends数组以强制 Eloquent 模型将其附加到任何toArray()调用模型实例，这就是toJson()将模型转换为 JSON 时使用。

首先获取所有列表值然后使用groupBy and map收集方法，但没有原生的 Eloquent 机制可供使用hasManyThrough通过多对多关系。有一个这里有不同的方法 https://stackoverflow.com/questions/23788844/hasmanythrough-with-one-to-many-relationship/23789210#23789210如果你不喜欢这个。

The 列表特征值 model:

class ListingFeatureValue extends Model
{
    public $table = 'listings_features_values';

    public function type()
    {
        return $this->belongsTo(ListingFeatureType::class, 'feature_type_id');
    }
}

我在这里展示这个模型是因为type()关系被称为getFeaturesByTypeAttribute()上面的方法，不希望有任何混乱。

而且，只是为了完整起见，列表功能类型 model:

class ListingFeatureType extends Model
{
    public $table = "listings_features_types";

    public function listings()
    {
        return $this->hasMany(ListingFeatureValue::class, 'listing_feature_type_id');
    }
}

如果您想立即加载列表及其功能和类型以获得所有列表的完整输出，您可以这样做：

App\Listing::with('features.type')->get()->toJson();

我的迁移文件如下所示：

//create_listings_table
Schema::create('listings', function (Blueprint $table) {
    $table->increments('id');
    $table->string('uuid');
    $table->timestamps();
});

//create_listings_features_values_table
Schema::create('listings_features_values', function (Blueprint $table) {
    $table->increments('id');
    $table->string('listing_feature_text');
    $table->integer('listing_feature_type_id')->unsigned();
    $table->timestamps();
});

//create_listings_features_types_table    
Schema::create('listings_features_types', function (Blueprint $table) {
    $table->increments('id');
    $table->string('name');
    $table->timestamps();
});

//create_listings_features_table
Schema::create('listings_features', function(Blueprint $table){
    $table->integer('listing_id')->unsigned();
    $table->integer('listing_feature_id')->unsigned();
});

您可以在此处了解有关 Collection 方法的更多信息：

https://laravel.com/docs/5.3/collections#available-methods https://laravel.com/docs/5.3/collections#available-methods

...并在这里急切加载：

https://laravel.com/docs/5.3/eloquent-relationships#eager-loading https://laravel.com/docs/5.3/eloquent-relationships#eager-loading

...以及这里的多对多关系：

https://laravel.com/docs/5.3/eloquent-relationships#many-to-many https://laravel.com/docs/5.3/eloquent-relationships#many-to-many