Check whether entity is referenced in a foreign table and get it entities

Question

Is there a way to check whether a entity is referenced in a foreign table (check foreign key relationship existence) and get the entities or ids from these foreign tables that are related?

Here is the situation: I have a bunch of entities to delete. But some of them can be referenced in other tables. I'm working in a generic way, so I don't know which model I'm working with neither what are the linkings It has. What I want is to filter these entities that can't be deleted and get the entities or ids from the foreign tables that are associated to the model I'm working so I can show them after the proccess.

The code would be basically in this way:

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
}

If I wasn't clear, please help me at comments. It was very hard for me to develop this question.

---

Suppose I'm working with Companies and I have to delete some of them:

I have a list of companies to remove, but I can remove just the ones that are not related to Workers and Clients . Also, I want to retrieve the Workers and Clients that are linked.

Answer 1

Here's the function I wrote for doing this:

    /**
     * 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;
    }