我认为最好的方法是遵循工作流程：
1.获取要克隆对象
1.检查集合并删除所有ID
1.转换为数组并在$this->Questionnaires->newEntity($arrayData, ['associated' => ['Questions', '...']]);中使用
1.现在，保存新实体以及要保留的所有相关数据
AFAIK没有“更聪明”的方法来克隆蛋糕3中的关联实体：-）

您也可以使用this plugin。您只需要配置行为，它就可以为您提供其他功能，比如设置默认值或向某些字段追加文本。

使用EntityInteface toArray（）来获取它的所有字段：

$newEtity = $someTable->newEntity($oldEtity->toArray());
unset($newDevice->created);
unset($newDevice->id);
$someTable->save($newEntity);

$original = $this->Table->get($id)->toArray();
$copy = $this->Table->newEntity();
$copy = $this->Table->patchEntity($copy, $original);

unset($copy['id']);
// Unset or modify all others what you need

$this->Table->save($copy);

这样完美地工作：）

当我需要类似的东西时，我是这样做的（适用于问卷调查的例子）：

// load the models
$this->loadModel('Questionnaire');
$this->loadModel('Questions');
// get the questions to questionnaire association - will need the PK name
$qAssoc = $this->{'Questions'}->associations()->get('Questionnaire');
// get the existing entity to copy
$existingEntity = $this->{'Questionnaire'}->get($id, [
    'contain' => ['Questions'],
]);
// clean up the existing entity
$existingEntity->unsetProperty($this->{'Questionnaire'}->getPrimaryKey());
$existingEntity->unsetProperty('created');
$existingEntity->unsetProperty('modified');
// clean up the associated records of the existing entity
foreach ($existingEntity->questions as &$q) {
    $q->unsetProperty($this->{'Questions'}->getPrimaryKey());
    $q->unsetProperty($qAssoc->getForeignKey());
}
// create a new entity and patch it with source data
$newEntity = $this->{'Questionnaire'}->patchEntity(
        $this->{'Questionnaire'}->newEntity(),
        $existingEntity->toArray()
);
// save the new entity
$result = $this->{'Questionnaire'}->save($existingEntity);

参考文献：

• https://api.cakephp.org/3.0/class-Cake.ORM.Entity.html
• https://api.cakephp.org/3.0/class-Cake.ORM.Table.html