检查实体是否在外部表中被引用并获取实体

Question

有没有办法检查一个实体是否在外部表中被引用（检查外键关系是否存在）并从这些相关的外部表中获取实体或 id？

情况如下：我有一堆实体要删除。但其中一些可以在其他表中引用。我正在以一种通用的方式工作，所以我不知道我正在使用哪个模型，也不知道它有什么链接。我想要的是过滤这些无法删除的实体，并从与我正在工作的模型关联的外部表中获取实体或 ID，以便在处理后显示它们。

代码基本上是这样的：

public function removeEntities($table_alias, $data){
    $data = $this->checkData($data); //do some work...
    $table_object = TableRegistry::get($table_alias);

    // here I'd like to get the entities or ids from tables related to $table_object that can't be deleted
    $data = $this->check_relationship($table_object, $data);

    $table_object->deleteAll(["common_index IN" => $data["to_delete"]]); //remove the guys that are related to nobody
    return $data["cant_delete"]; //return the foreign entities/ids which are related to entities from $table_object
}

如果我不清楚，请在 cmets 帮助我。我很难提出这个问题。

---

假设我正在使用Companies，我必须删除其中一些：

我有一个要删除的公司列表，但我可以只删除与Workers 和Clients 无关的公司。另外，我想检索链接的Workers 和Clients。

Answer 1

这是我为此编写的函数：

    /**
     * Use model associations to determine whether a record can be deleted.
     *
     * @param mixed $id The id of the record to delete
     * @param array $ignore Optional list of models to ignore
     * @param array $ignoreDeep Optional list of models to ignore IF they themselves have no dependencies
     * @return mixed Text list of dependencies found, or false if none
     */
    public function dependencies($id, array $ignore = [], array $ignoreDeep = []) {
            if ($id === null) {
                    return false;
            }

            $dependencies = [];
            $associations = $this->associations();

            foreach ($associations->type('BelongsToMany') as $association) {
                    $class = $association->name();
                    $foreign_key = $association->foreignKey();
                    $through = $association->junction()->alias();
                    $dependent = $association->junction()->find()->where(["$through.$foreign_key" => $id]);

                    $association_conditions = $association->conditions();
                    if (!empty($association_conditions)) {
                            $dependent->andWhere($association_conditions);
                    }

                    if (in_array($class, $ignoreDeep) || array_key_exists($class, $ignoreDeep)) {
                            foreach ($dependent->extract($association->targetForeignKey())->toArray() as $deepId) {
                                    if (array_key_exists($class, $ignoreDeep)) {
                                            $deep = $association->dependencies($deepId, $ignoreDeep[$class]);
                                    } else {
                                            $deep = $association->dependencies($deepId);
                                    }
                                    if ($deep) {
                                            $dependencies[] = __('{0} {1} (with {2})', __(Inflector::delimit(Inflector::singularize($class), ' ')), $deepId, $deep);
                                    }
                            }
                    } else if (!in_array($class, $ignore)) {
                            if ($dependent->count() > 0) {
                                    $dependencies[] = $dependent->count() . ' ' . __(Inflector::delimit($class, ' '));
                            }
                    }

                    // BelongsToMany associations also create HasMany associations for the join tables.
                    // Ignore them when we get there.
                    $ignore[] = $through;
            }

            foreach ($associations->type('HasMany') as $association) {
                    $class = $association->name();
                    $foreign_key = $association->foreignKey();
                    $dependent = $association->target()->find()->where(["$class.$foreign_key" => $id]);

                    $association_conditions = $association->conditions();
                    if (!empty($association_conditions)) {
                            $dependent->ansWhere($association_conditions);
                    }

                    if (in_array($class, $ignoreDeep) || array_key_exists($class, $ignoreDeep)) {
                            foreach ($dependent->extract($association->primaryKey())->toArray() as $deepId) {
                                    if (array_key_exists($class, $ignoreDeep)) {
                                            $deep = $association->dependencies($deepId, $ignoreDeep[$class]);
                                    } else {
                                            $deep = $association->dependencies($deepId);
                                    }
                                    if ($deep) {
                                            $dependencies[] = __('{0} {1} (with {2})', __(Inflector::delimit(Inflector::singularize($class), ' ')), $deepId, $deep);
                                    }
                            }
                    } else if (!in_array($class, $ignore)) {
                            if ($dependent->count() > 0) {
                                    $dependencies[] = $dependent->count() . ' ' . __(Inflector::delimit($class, ' '));
                            }
                    }
            }

            if (!empty($dependencies)) {
                    return implode(', ', $dependencies);
            }
            return false;
    }