How to unset the id of a cloned PHP object

Question

I am working on a project that uses Docrtrine and Symfony 2.7. I have a Document entity that I want to clone, and I of course need to make sure that I don't have a duplicate primary key. Here is what I have attempted so far:

/**
 * Document
 *
 * @ORM\Table(name="documents")
 */
class Document {
    public function __clone(){
        $newObj = clone $this;
        $newObj->id = null;
        return $newObj;
    }
...
}

This does not seem to do much, however, as when I call clone myDocument and then try to persist, I still get this message:

SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '1' for key 'UNIQ_A2B07288ECC6147F'

How can I get my object's primary key to revert to a null or auto-incremented state?

=====

Upate: Using

public function __clone(){
    $this->id = null;
}

still results in the same error. Full error text:

An exception occurred while executing 'INSERT INTO documents (usageFrom, usageTo, status, workflow_identifier, created_date, modified_date, language_id, translationRoot_id, ownerGroup_id, responsibleUser_id, production_id, media_id, created_user, modified_user) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)' with params ["2018-06-28 09:54:37", "2018-06-28 09:54:37", 100, "4cc723c2a5730c1b9c2ed6428ae57205", "2018-06-28 09:54:37", "2018-06-28 09:54:37", null, null, null, null, 1, null, 1, 1]:

SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '1' for key 'UNIQ_A2B07288ECC6147F'

try with [detach](https://www.doctrine-project.org/projects/doctrine-orm/en/2.6/reference/working-with-objects.html#detaching-entities) or make a copy constructor (or check if [this answer](https://stackoverflow.com/a/186008/2270041) works for you) — Matteo, Jun 28 '18 at 10:35

score 7 · Accepted Answer · answered Jun 28 '18 at 11:07

7

This is not how PHP’s cloning works. Think of __clone like of __construct. In the __clone method, you must assign the new values to $this.

class Document 
{
    public function ___clone()
    {
        // simple as that
        $this->id = null;
    }
}

In your current code, the $newObj is going to be thrown away, while the cloned object still has the original ID.

Also, remember to clone child objects in your __clone method if you want to create a deep copy, otherwise you’ll end up with two entities referencing the same children. (Or, after persisting/reloading: One of the entities will have lost its children.)

answered Jun 28 '18 at 11:07

lxg

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Thanks for your answer. I have updated the question to show what happens when I try your suggestion. – Mayor of the Plattenbaus Jun 28 '18 at 11:40
Is the `UNIQ_A2B07288ECC6147F` index on the Document table or one of the child tables? – lxg Jun 28 '18 at 11:51
Aha -- it looks like it's not a problem with the ID. From the MAKE TABLE statement for my documents table: `UNIQUE KEY UNIQ_A2B07288ECC6147F (production_id),` ... so that's a nice catch. – Mayor of the Plattenbaus Jun 28 '18 at 12:06
is the `production` entity a child entity of `document` or an independent entity? – lxg Jun 28 '18 at 12:16
It's an entity of its own. – Mayor of the Plattenbaus Jun 28 '18 at 12:16
1

You didn’t detach the entity or clear the entity manager, did you? Because it looks like Doctrine is trying to persist the Production entity again. – lxg Jun 28 '18 at 12:18
Correct -- I didn't detach the entity, nor did I clear the entity manager. – Mayor of the Plattenbaus Jun 28 '18 at 12:22

How to unset the id of a cloned PHP object

1 Answers1