php - Laravel 有Many Many to Many To One Eloquent

Question

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。

鉴于我有一辆汽车并且汽车可以有很多特征，但特征也由特征类型分隔，我怎样才能返回所有特征，分隔特征类型，对于所说的汽车？

我有四个表，listings_features 是数据透视表：

列表（ID）
Listings_features (listing_id, feature_id)
Listings_features_types (id, 类型)
Listings_features_values（id，listing_feature_type_id，值）

我有以下代码，它产生了我需要的东西，但是当我使用它时，我得到一个 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生成数据的代码（不是坚定的）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 模型关系以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？

如果你做到了这一步，谢谢！

更新：

我无法让它按原样工作，我遇到了一个 SQL 错误，这让我觉得我需要一个 belongsToManyThrough，所以我可以指定表名：

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下面作为答案发布的确切代码并将 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');
    }

我得到以下输出：

"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，然后按其中的特征分组，而不是每个特征都附加一个类型，那就太好了。使解析显示变得更加困难。感谢您迄今为止的帮助！

更新 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');
});

更新 3 从下面的答案中进行更改（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"
            }
         }
      }
   ]
}

score 9 · Accepted Answer

Listing您可以在模型和模型之间使用多对多关系，然后使用Collection 方法ListingFeatureValue按给定列表的类型对给定列表的相关列表功能进行分组。groupBy

上市模式：

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();
    }

}

是这里的亮点getFeatureTypesAttribute()，因为您可以将它与appends数组结合起来，以强制 Eloquent 模型将其附加toArray()到对模型实例的任何调用中，这是toJson()将模型转换为 JSON 时使用的方法。

groupBy首先获取所有列表值然后使用和集合方法划分它们似乎有点令人费解map，但是没有hasManyThrough通过多对多关系使用的原生 Eloquent 机制。如果你不喜欢这个，这里有另一种方法。

ListingFeatureValue模型：

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在上面type()的方法中调用了关系getFeaturesByTypeAttribute()并且不希望有任何混淆。

而且，为了完整起见，ListingFeatureType模型：

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

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

如果您想预先加载列表及其特性和类型以完整输出所有列表，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

...并在这里急切加载：

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

php - Laravel 有Many Many to Many To One Eloquent

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