Laravel 同一模型上的多对多
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【中文标题】Laravel 同一模型上的多对多【英文标题】：Laravel Many-to-many on the same model 【发布时间】：2021-10-31 03:40:18 【问题描述】：它应该很简单，但是出了点问题，我想知道为什么。 我需要同一模型的多对多关系，理论上我知道如何做到这一点，但我收到了奇怪的结果。可能是由非整数索引列引起的。 Pn 型号：
class Pn extends Model
protected $primaryKey = 'pn';
protected $guarded = [];
public function bom()
return $this->belongsToMany(
'App\Models\Pn',
'boms',
'parent_pn',
'child_pn',
);
public function where_used()
return $this->belongsToMany(
'App\Models\Pn',
'boms',
'child_pn',
'parent_pn',
);
Pn 迁移：
class CreatePnsTable extends Migration
public function up()
Schema::create('pns', function (Blueprint $table)
$table->string('pn')->primary()->index();
$table->string('pd');
$table->string('ifs_pn');
$table->string('ifs_pd');
$table->timestamps();
);
BOM（枢轴）迁移：
class CreateBomsTable extends Migration
public function up()
Schema::create('boms', function (Blueprint $table)
$table->id();
$table->string('parent_pn');
$table->foreign('parent_pn')->references('pn')->on('pns');
$table->string('child_pn');
$table->foreign('child_pn')->references('pn')->on('pns');
$table->integer('sort');
$table->string('dp')->default('0');
$table->float('qty')->default(0);
$table->string('note')->default('');
$table->timestamps();
);
PN 播种机：
public function run()
Pn::create([
'pn' => 'A1',
'pd' => "first_part",
'ifs_pn' => 'IFS_A1',
'ifs_pd' => "IFS_first_part",
]);
Pn::create([
'pn' => 'A2',
'pd' => "second_part",
'ifs_pn' => 'IFS_A2',
'ifs_pd' => "IFS_second_part",
]);
Pn::create([
'pn' => 'A3',
'pd' => "third_part",
'ifs_pn' => 'IFS_A3',
'ifs_pd' => "IFS_third_part",
]);
Pn::create([
'pn' => 'A4',
'pd' => "fourth_part",
'ifs_pn' => 'IFS_A4',
'ifs_pd' => "IFS_fourth_part",
]);
Pn::create([
'pn' => 'A5',
'pd' => "fifth_part",
'ifs_pn' => 'IFS_A5',
'ifs_pd' => "IFS_fifth_part",
]);
Pn::create([
'pn' => 'A6',
'pd' => "sixth_part",
'ifs_pn' => 'IFS_A6',
'ifs_pd' => "IFS_sixth_part",
]);
Pn::create([
'pn' => 'A7',
'pd' => "seventh_part",
'ifs_pn' => 'IFS_A7',
'ifs_pd' => "IFS_seventh_part",
]);
BOM 播种机：
public function run()
Bom::create([
'parent_pn' => 'A3',
'child_pn' => "A4",
'sort' => 10,
'dp' => "front",
'qty' => 1,
'note' => 'test',
]);
Bom::create([
'parent_pn' => 'A3',
'child_pn' => "A5",
'sort' => 20,
'dp' => "back",
'qty' => 4,
'note' => '',
]);
Bom::create([
'parent_pn' => 'A1',
'child_pn' => "A2",
'sort' => 10,
'dp' => "top",
'qty' => 2,
'note' => 'test2s',
]);
Bom::create([
'parent_pn' => 'A1',
'child_pn' => "A3",
'sort' => 20,
'dp' => "bottom",
'qty' => "2.5",
'note' => '',
]);
Bom::create([
'parent_pn' => 'A1',
'child_pn' => "A4",
'sort' => 30,
'dp' => "back",
'qty' => 1,
'note' => '',
]);
Bom::create([
'parent_pn' => 'A1',
'child_pn' => "A4",
'sort' => 40,
'dp' => "front",
'qty' => 5,
'note' => '',
]);
Bom::create([
'parent_pn' => 'A1',
'child_pn' => "A6",
'sort' => 50,
'dp' => "under",
'qty' => 5,
'note' => '',
]);
正在执行（对于 $id = 'A1'）：
public function show($id)
$pn = PN::find($id);
$bom = $pn->bom()->get();
$where_used = $pn->where_used()->get();
return [
'pn' => $pn,
'bom' => $bom,
'where_used' => $where_used,
];
结果：
"pn":
"pn":0,
"pd":"first_part",
"ifs_pn":"IFS_A1",
"ifs_pd":"IFS_first_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z"
,
"bom":
[
"pn":0,
"pd":"fourth_part",
"ifs_pn":"IFS_A4",
"ifs_pd":"IFS_fourth_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"parent_pn":"A3",
"child_pn":"A4"
,
"pn":0,
"pd":"fifth_part",
"ifs_pn":"IFS_A5",
"ifs_pd":"IFS_fifth_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"parent_pn":"A3",
"child_pn":"A5"
,
"pn":0,
"pd":"second_part",
"ifs_pn":"IFS_A2",
"ifs_pd":"IFS_second_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"parent_pn":"A1",
"child_pn":"A2"
,
"pn":0,
"pd":"third_part",
"ifs_pn":"IFS_A3",
"ifs_pd":"IFS_third_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"parent_pn":"A1",
"child_pn":"A3"
,
"pn":0,
"pd":"fourth_part",
"ifs_pn":"IFS_A4",
"ifs_pd":"IFS_fourth_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"parent_pn":"A1",
"child_pn":"A4"
,
"pn":0,
"pd":"fourth_part",
"ifs_pn":"IFS_A4",
"ifs_pd":"IFS_fourth_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"parent_pn":"A1",
"child_pn":"A4"
,
"pn":0,
"pd":"sixth_part",
"ifs_pn":"IFS_A6",
"ifs_pd":"IFS_sixth_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"parent_pn":"A1",
"child_pn":"A6"
],
"where_used":
[
"pn":0,
"pd":"third_part",
"ifs_pn":"IFS_A3",
"ifs_pd":"IFS_third_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"child_pn":"A4",
"parent_pn":"A3"
,
"pn":0,
"pd":"third_part",
"ifs_pn":"IFS_A3",
"ifs_pd":"IFS_third_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"child_pn":"A5",
"parent_pn":"A3"
,
"pn":0,
"pd":"first_part",
"ifs_pn":"IFS_A1",
"ifs_pd":"IFS_first_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"child_pn":"A2",
"parent_pn":"A1"
,
"pn":0,
"pd":"first_part",
"ifs_pn":"IFS_A1",
"ifs_pd":"IFS_first_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"child_pn":"A3",
"parent_pn":"A1"
,
"pn":0,
"pd":"first_part",
"ifs_pn":"IFS_A1",
"ifs_pd":"IFS_first_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"child_pn":"A4",
"parent_pn":"A1"
,
"pn":0,
"pd":"first_part",
"ifs_pn":"IFS_A1",
"ifs_pd":"IFS_first_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"child_pn":"A4",
"parent_pn":"A1"
,
"pn":0,
"pd":"first_part",
"ifs_pn":"IFS_A1",
"ifs_pd":"IFS_first_part",
"created_at":"2021-09-01T14:10:30.000000Z",
"updated_at":"2021-09-01T14:10:30.000000Z",
"pivot":
"child_pn":"A6",
"parent_pn":"A1"
]
它将所有来自 DB 的 PN 作为孩子和父母返回，为什么？ PN = 0 而不是 A1、A2 等... 请帮忙
【问题讨论】：
【参考方案1】：我找到了！ 我已添加：
protected $keyType = 'string';
到 PN 模型，它的工作原理！
【讨论】：
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