相同用户之间的关系 table

Question

我有 3 个不同的角色（Admin、Coach 和 Runner）。一个用户只有一个角色。

问题是当我尝试将用户与角色 Coach 以及用户与角色 Runner 相关联时。逻辑应用就是这个；我可以创建跑步者和教练，但每个跑步者只属于一个教练，一个教练有很多跑步者。

如何在相同的用户 table 上处理此问题，然后在用户模型及其关系上处理此问题。

Answer 1

首先，您需要外键为 nullable，您可以在用户的 migration 文件中指定：

your_migration_file.php

public function up()
{
    Schema::create('users', function (Blueprint $table) {
        $table->bigIncrements('id');
        $table->string('name');
        // your columns
        $table->unsignedBigInteger('coach_id')->nullable();  // <-----
    }); //                                    ^^^^^^^^^^^^
}

Notice that doing this you won't be able to add database constrains, but this isn't necessary anyways. Also, you might need to refresh your migrations.

然后在您的 User 模型中您需要定义您的关系：

User.php

class User extends Model {

    /** a Runner has a Coach. */
    public function coach()
    {
        return $this->belongsTo(User::class, 'coach_id');
    }

    /** a Coach teaches many Runners */
    public function runners()
    {
        return $this->hasMany(User::class, 'coach_id');
    }

然后您可以查询 eager load 并限制结果：

YourController.php

public function myCoolFunction()
{
    $runners = User::with('coach')->whereNotNull('coach_id')->get();
    $coaches = User::with('runners')->whereNull('coach_id')->get();
}

当然这个查询看起来很难看，所以你也可以在你的 User 模型中定义 local query scopes：

class User extends Model {

    // some code..

    public function scopeCoaches($query)
    {
        return $query->hasRole('coach'); // maybe you use a role package?            
     // return $query->whereNull('coach_id'); // or my basic approach used before
    }

    public function scopeRunners($query)
    {
        return $query->hasRole('srunner'); // maybe you use a role package?            
     // return $query->whereNotNull('coach_id'); // or my basic approach used before
    }
}

然后使用你的范围：

public function myCoolFunction()
{
    $runners = User::with('coach')->coaches()->get();
    $coaches = User::with('runners')->runners()->get();
}

相同用户之间的关系 table

Relation between same users table

php

database

roles

laravel

eloquent