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Laravel的hasMany，多对多和多对一关系的Eloquent模型

phplaraveleloquent
15

我尝试过使用 Laravel 的方式来解决这个问题，但是并没有取得太大的成功。所以我提出了两个问题。

假设我有一辆汽车，并且这辆汽车可以拥有许多功能，但是这些功能也被分为不同类型，那么我该如何返回所有针对该汽车分类的功能？

我有四张表格，listings_features 是中间表：

  • listings (id)
  • listings_features (listing_id, feature_id)
  • listings_features_types (id, type)
  • listings_features_values (id, listing_feature_type_id, value)

我有以下代码可以实现我需要的功能，但是当我使用它时，会出现 Laravel 错误... "Call to a member function addEagerConstraints() on string" ... 因为我是这样调用它的：

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

我用来生成所需数据格式的代码（不一定是固定的）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);
}

返回的结果如下：

[
  {
    "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;

}

我该如何建立Laravel模型关联来达到与上述方法相同的结果集？或者，如何以上述方式调用它但避免错误发生？
如果您已经阅读到这里，谢谢！
更新：
按照当前状态，我无法使其正常工作，我出现了一个SQL错误，这让我感觉需要使用belongsToManyThrough以便能够指定表名：
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))

但是使用下面@Carter Fort的答案中发布的确切代码，并将features()方法更改为
return $this->belongsToMany(ListingFeatureValue::class, 'listings_features', 'listing_id', 'feature_id');

同时添加到模型ListingFeatureValue中。
public function type()
    {
        return $this->belongsTo(ListingFeatureType::class, 'listing_feature_type_id', 'id');
    }

我得到的输出是： 

"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"
}
},
  ...

这比我做得好，但如果结果按类型分组，然后再按功能进行分组，而不是每个功能都带有类型，那就更好了。这样会使显示解析更加困难。到目前为止，感谢你的帮助！ 更新2 以下是我的模式文件：
// 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 根据下面答案中的更改（一旦完全工作，我将发布所有代码），我接近我想要的结果。

"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"
}

// .... ]

What I would like is:

{
   "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"
            }
         }
      }
   ]
}
请发布您的模型（listing_features表），因为您的public function features()不太对劲。 - Bagus Tesa
另外，在你问之前，我正在为现有应用程序制作一个API，这就是为什么表名和其他内容被定义的原因。 :) - Spechal
1
所以基本上你想要能够检索所有的“列表”，每个“列表”都有包含“列表特征值”的“列表特征类型”，是吗？ - Bagus Tesa
没错。 <文本长度限制> - Spechal
1个回答
9
你可以在Listing和ListingFeatureValue模型之间使用多对多关系，然后使用groupBy集合方法按类型分组给定Listing的相关listing功能。
Listing模型:
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()是主角，因为您可以将其与appends数组组合使用，强制Eloquent模型将其附加到对模型实例的任何toArray()调用中，这就是在将您的模型转换为JSON时toJson()所使用的方法。
可能看起来有点复杂，首先获取所有列表值，然后使用groupBy和map集合方法将它们分成几部分，但是没有原生的Eloquent机制可以通过多对多关系使用hasManyThrough。如果您不喜欢这种方法，可以尝试不同的方法。 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，因为上面的getFeaturesByTypeAttribute()方法中调用了type()关系，我不希望有任何混淆。

为了完整起见，这是ListingFeatureType模型：

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

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

如果您想要使用它们的功能和类型来急切加载列表以完整输出所有列表，可以像这样操作：
App\Listing::with('features.type')->get()->toJson();

我的��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();
});

您可以在这里了解更多有关集合方法的信息: https://laravel.com/docs/5.3/collections#available-methods 还可以在这里了解更多关于急切加载的内容: https://laravel.com/docs/5.3/eloquent-relationships#eager-loading 以及这里了解更多关于多对多关系的内容: https://laravel.com/docs/5.3/eloquent-relationships#many-to-many
基于更新2：有一个缺失的表格，这是我的问题的核心。我有四个表。列表、列表特征、列表特征类型、列表特征值。列表保存列表，列表特征是到列表特征值的中间表，它具有特征的值。列表特征值还具有列表特征类型ID，以链接到列表特征类型。我将发布模拟架构。 - Spechal
我已经更新了我的答案，展示如何使用listings_features作为数据透视表来连接Listing和ListingFeatureValue模型。 - Carter Fort
我们非常接近了。我基本上想要的是我将在更新3中发布的相反操作。当我们把它全部搞定时，我会发布所有我的模型和迁移，以帮助其他人，因为这已经被标记了三次。 - Spechal
我已经更新了我的答案，添加了一个新的 getFeatureTypesAttribute 方法，它将返回你要查找的集合。 - Carter Fort
太好了！我稍后会更新原帖。赏金已经发放！ - Spechal
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