如何使用Doctrine正确设置实体更新时间？

Question

Column in MySQL table is called "updated_at". It's of datetime type, not null. Doctine type is datetime as well.

CREATE TABLE `example` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `created_at` datetime NOT NULL,
  `updated_at` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

Some\Bundle\Entity\Example:
    type:            entity
    table:           examples
    fields:
        id:
            id:     true
            type:   integer
            generator:
                strategy: IDENTITY
        ...
        createdAt:
            type:   datetime
            column: created_at
        updatedAt:
            type:   datetime
            column: updated_at

$e = new Example;
$e->setCreatedAt(new \DateTime);
$em->persist($e);
/* after this I need $e->updatedAt to be MySQL's default 0 (0000-00-00) */
$em->flush();
/* but it will throw 
"Integrity constraint violation: 1048 Column 'updated_at' cannot be null" 
if I won't set it in Example::__contruct() 
which I don't see any reason to do 
apart from complying with Doctrine shortcomings. */

If entity wasn't ever updated after it was created I don't want to have any value in this column.

How to skip this column or set proper value upon persist without changing MySQL or Doctrine types (because they are right)?

Answer 1

Two options. Use the Timestampable as i mentioned in the comments. For symfony it's integrated in the StofDoctrineExtensionsBundle . Then you simply add it to your mapping yaml and no further code in controllers, services, etc. is required.

Option two: Set the updated_at to NULL instead of NOT NULL. NOT NULL means, there must be a value (eg 0000-00-00 at least). If you allow a NULL value in MySQL, you will reach what you consider.

Answer 2

Doctrine cannot skip columns, uses all fields which you defined in metadata config.

You should set some default value in constructor, empty string suits well for almost all types.

It will be used just once upon persist, subsequent fetches won't trigger construct.