Laravel hasMany 多对多对一 Eloquent

Question

我没能用 Laravel 的方式解决这个问题。所以我提出两个问题。

假设我有一辆车，那辆车可以有很多特征，但特征也被特征类型分开，我怎么能 return 所有特征，分开特征类型，对于所说的汽车？

我有四个 table，listings_features 是支点 table：

列表（id）
listings_features (listing_id, feature_id)
listings_features_types (id, 类型)
listings_features_values（id，listing_feature_type_id，值）

我有下面的代码，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... "Call to a member function addEagerConstraints() on string" ... 因为我这样调用它：

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

我用来生成我想要的格式（不是固定格式）的数据的代码是

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);
}

哪个 returns:

[
  {
    "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（非常基础，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 这样我就可以指定 table 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))

但是使用确切的代码 posted 作为@Carter Fort 下面的答案并将 features() 方法更改为

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

同时添加到模型 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，那就更好了。使其更难解析显示。感谢迄今为止的帮助！

更新 2

这些是我的架构文件：

// 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 根据下面的答案进行更改（一旦工作，我将 post 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"
            }
         }
      }
   ]
}

Answer 1

您可以在 Listing 和 ListingFeatureValue 模型之间使用多对多关系，然后使用 [=17= 按给定列表的类型对给定列表的相关列表功能进行分组] 采集方法。

列表型号：

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();
    }

}

getFeatureTypesAttribute() 是这里的明星，因为您可以将它与 appends 数组结合使用，以强制 Eloquent 模型将其附加到任何 toArray() 调用模型实例，这是 toJson() 在将模型转换为 JSON.

时使用的

首先获取所有列表值然后使用 groupBy 和 map 收集方法划分它们似乎有点令人费解，但没有原生的 Eloquent 机制来使用hasManyThrough 通过多对多关系。如果您不喜欢这个，还有一个 different approach here。

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 type() 关系在上面的 getFeaturesByTypeAttribute() 方法中被调用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收集方法的更多信息：

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

...并在此处预加载：

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

Laravel hasMany 多对多对一 Eloquent

Laravel hasMany Many to Many To One Eloquent

php

laravel

eloquent

laravel-eloquent