我在 Controller 上的删除方法是这样的:

<?php
public function deleteMessage($id, $seller_id, $buyer_id)
{
    //if the seller delete
    if($seller_id == auth()->user->id)
        //const DELETED_AT = 'deleted_by_seller';
    //if the buyer delete
    else($buyer_id == auth()->user->id)
        //const DELETED_AT = 'deleted_by_buyer';

    $result = Message::destroy($id);
    return $result;
}

我的模型是这样的:

<?php
namespace App\Models;
use Jenssegers\Mongodb\Eloquent\Model as Eloquent; 
use Jenssegers\Mongodb\Eloquent\HybridRelations;
use Jenssegers\Mongodb\Eloquent\SoftDeletes;
class MessageThread extends Eloquent
{
    use HybridRelations; 
    use SoftDeletes; 
    // const DELETED_AT = 'deleted_by_seller';
    // const DELETED_AT = 'deleted_by_buyer';
    protected $connection = 'mongodb';
    protected $dates = ['deleted_by_seller', 'deleted_by_buyer'];
    protected  $fillable = ['subject', 'information', 'created_at', 'update_at'];
}

我想喜欢这个:

如果卖家删除消息则:const DELETED_AT = 'deleted_by_seller';

如果买家删除消息则:const DELETED_AT = 'deleted_by_buyer';

我该怎么做？

最佳答案

更新:

the original article refers my personal blog

软删除特征

在laravel中，我们通过扩展Illuminate\Database\Eloquent\Model来定义我们自己的模型。要软删除模型实例，我们应该在模型中使用 Illuminate\Database\Eloquent\SoftDeletes 特性。 runSoftDelete()是SoftDeletes trait中的关键函数，构建一个sql查询，获取用于标记记录是否被删除的列，然后更新该列带有当前时间戳。

protected function runSoftDelete()
{
    $query = $this->newQueryWithoutScopes()->where($this->getKeyName(), $this->getKey());
    $this->{$this->getDeletedAtColumn()} = $time = $this->freshTimestamp();
    $query->update([$this->getDeletedAtColumn() => $this->fromDateTime($time)]);
}

Delete()过程

当我们在模型上调用 delete() 函数时会发生什么？

由于我们自己的模型扩展了Illuminate\Database\Eloquent\Model，所以我们看一眼。这是 delete() 函数:

public function delete()
{
    if (is_null($this->getKeyName())) {
        throw new Exception('No primary key defined on model.');
    }

    if ($this->exists) {
        if ($this->fireModelEvent('deleting') === false) {
            return false;
        }

        // Here, we'll touch the owning models, verifying these timestamps get updated
        // for the models. This will allow any caching to get broken on the parents
        // by the timestamp. Then we will go ahead and delete the model instance.
        $this->touchOwners();

        $this->performDeleteOnModel();

        $this->exists = false;

        // Once the model has been deleted, we will fire off the deleted event so that
        // the developers may hook into post-delete operations. We will then return
        // a boolean true as the delete is presumably successful on the database.
        $this->fireModelEvent('deleted', false);

        return true;
    }
}

代码清晰。它确保模型有一个 primaryKey 并且实例首先存在于数据库中。然后调用performDeleteOnModel()函数执行删除操作。一定要注意!

这里我们应该知道:

An inherited member from a base class is overridden by a member inserted by a Trait. The precedence order is that members from the current class override Trait methods, which in turn override inherited methods.

因此，当调用 performDeleteOnModel() 时执行的确切函数是 SoftDeletes 特征中的同名函数，而不是 Model 中的函数类(class)。现在我们回到特征:

protected function performDeleteOnModel()
{
    if ($this->forceDeleting) {
        return $this->newQueryWithoutScopes()->where($this->getKeyName(), $this->getKey())->forceDelete();
    }

    return $this->runSoftDelete();
}

好吧，它会调用我们在开头讨论过的 runSoftDelete()。这就是软检测的过程。

获取问题

提问者希望在删除时使用不同的DELETED_AT 列。通过仅覆盖 getDeletedAtColumn() 来保持软删除机制的良好运行还有很多不足之处。为什么被删除的模型被软删除了，结果还在结果中？

当 Model 类被构造时，它将通过调用它们的 boot[TraitName] 方法来启动特征。因此这里是 bootSoftDelete() 方法。

protected static function bootTraits()
{
    foreach (class_uses_recursive(get_called_class()) as $trait) {
        if (method_exists(get_called_class(), $method = 'boot'.class_basename($trait))) {
            forward_static_call([get_called_class(), $method]);
        }
    }
}

现在让我们再次关注 SoftDeletes 特性。

public static function bootSoftDeletes()
{
    static::addGlobalScope(new SoftDeletingScope);
}

这里的 trait 通过调用 static::addGlobalScope() 注册了一个具有 apply() 方法的 SoftDeletingScope 类。位于 Model 类中的方法将其存储到 $globalScopes 数组中。

public static function addGlobalScope(ScopeInterface $scope)
{
    static::$globalScopes[get_called_class()][get_class($scope)] = $scope;
}

当一个查询建立在一个模型上时，applyGlobalScopes()方法会被自动调用，一个一个地访问$globalScopes数组中的实例并调用它们的 apply() 方法。

public function applyGlobalScopes($builder)
{
    foreach ($this->getGlobalScopes() as $scope) {
        $scope->apply($builder, $this);
    }

    return $builder;
}

我们现在将揭开问题的面纱。在 SoftDeletingScope 类中:

public function apply(Builder $builder, Model $model)
{
    $builder->whereNull($model->getQualifiedDeletedAtColumn());

    $this->extend($builder);
}

它将在每个查询上添加一个约束，以选择那些 DELETED_AT 列为空的记录。这就是 SoftDeletes 的 secret 。

动态 DELETED_AT 列

首先，我需要重申，我不推荐使用动态 DELETED_AT 列的这种行为。

为了解决提问者的动态DELETED_AT列的问题，你需要用这样的apply()函数实现你自己的SoftDeletingScope类:

public function apply(Builder $builder, Model $model)
{
    $builder->where(function ($query){
        $query->where('DELETED_AT_COLUMN_1',null)->orWhere('DELETED_AT_COLUMN_2',null);
    });

    $this->extend($builder);
}

然后用它覆盖 bootSoftDeletes()

public static function bootSoftDeletes()
{
    static::addGlobalScope(new YourOwnSoftDeletingScope);
}

原答案:

您不能在运行时更改const 变量的值。所以你需要手动分配CREATED_AT的值。

关于php - 如何创造条件上的 Eloquent 模式？ (拉拉维尔 5.3)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42756671/