doctrine2/UPGRADE_TO_2_0

# Update from 2.0-BETA3 to 2.0-BETA4

## XML Driver <change-tracking-policy /> element demoted to attribute

We changed how the XML Driver allows to define the change-tracking-policy. The working case is now:

    <entity change-tracking-policy="DEFERRED_IMPLICT" />

# Update from 2.0-BETA2 to 2.0-BETA3

## Serialization of Uninitialized Proxies

As of Beta3 you can now serialize uninitialized proxies, an exception will only be thrown when
trying to access methods on the unserialized proxy as long as it has not been re-attached to the
EntityManager using `EntityManager#merge()`. See this example:

    $proxy = $em->getReference('User', 1);

    $serializedProxy = serialize($proxy);
    $detachedProxy = unserialized($serializedProxy);

    echo $em->contains($detachedProxy); // FALSE

    try {
        $detachedProxy->getId(); // uninitialized detached proxy
    } catch(Exception $e) {

    }
    $attachedProxy = $em->merge($detachedProxy);
    echo $attackedProxy->getId(); // works!

## Changed SQL implementation of Postgres and Oracle DateTime types

The DBAL Type "datetime" included the Timezone Offset in both Postgres and Oracle. As of this version they are now
generated without Timezone (TIMESTAMP WITHOUT TIME ZONE instead of TIMESTAMP WITH TIME ZONE).
See [this comment to Ticket DBAL-22](http://www.doctrine-project.org/jira/browse/DBAL-22?focusedCommentId=13396&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#action_13396)
for more details as well as migration issues for PostgreSQL and Oracle.

Both Postgres and Oracle will throw Exceptions during hydration of Objects with "DateTime" fields unless migration steps are taken!

## Removed multi-dot/deep-path expressions in DQL

The support for implicit joins in DQL through the multi-dot/Deep Path Expressions
was dropped. For example:

    SELECT u FROM User u WHERE u.group.name = ?1

See the "u.group.id" here is using multi dots (deep expression) to walk
through the graph of objects and properties. Internally the DQL parser
would rewrite these queries to:

    SELECT u FROM User u JOIN u.group g WHERE g.name = ?1

This explicit notation will be the only supported notation as of now. The internal
handling of multi-dots in the DQL Parser was very complex, error prone in edge cases
and required special treatment for several features we added. Additionally
it had edge cases that could not be solved without making the DQL Parser
even much more complex. For this reason we will drop the support for the
deep path expressions to increase maintainability and overall performance
of the DQL parsing process. This will benefit any DQL query being parsed,
even those not using deep path expressions.

Note that the generated SQL of both notations is exactly the same! You
don't loose anything through this.

## Default Allocation Size for Sequences

The default allocation size for sequences has been changed from 10 to 1. This step was made
to not cause confusion with users and also because it is partly some kind of premature optimization.

# Update from 2.0-BETA1 to 2.0-BETA2

There are no backwards incompatible changes in this release.

# Upgrade from 2.0-ALPHA4 to 2.0-BETA1

## EntityRepository deprecates access to protected variables

Instead of accessing protected variables for the EntityManager in
a custom EntityRepository it is now required to use the getter methods
for all the three instance variables:

* `$this->_em` now accessible through `$this->getEntityManager()`
* `$this->_class` now accessible through `$this->getClassMetadata()`
* `$this->_entityName` now accessible through `$this->getEntityName()`

Important: For Beta 2 the protected visibility of these three properties will be
changed to private!

## Console migrated to Symfony Console

The Doctrine CLI has been replaced by Symfony Console Configuration

Instead of having to specify:

    [php]
    $cliConfig = new CliConfiguration();
    $cliConfig->setAttribute('em', $entityManager);

You now have to configure the script like:

    [php]
    $helperSet = new \Symfony\Components\Console\Helper\HelperSet(array(
        'db' => new \Doctrine\DBAL\Tools\Console\Helper\ConnectionHelper($em->getConnection()),
        'em' => new \Doctrine\ORM\Tools\Console\Helper\EntityManagerHelper($em)
    ));

## Console: No need for Mapping Paths anymore

In previous versions you had to specify the --from and --from-path options
to show where your mapping paths are from the console. However this information
is already known from the Mapping Driver configuration, so the requirement
for this options were dropped.

Instead for each console command all the entities are loaded and to
restrict the operation to one or more sub-groups you can use the --filter flag.

## AnnotationDriver is not a default mapping driver anymore

In conjunction with the recent changes to Console we realized that the
annotations driver being a default metadata driver lead to lots of glue
code in the console components to detect where entities lie and how to load
them for batch updates like SchemaTool and other commands. However the
annotations driver being a default driver does not really help that much
anyways.

Therefore we decided to break backwards compability in this issue and drop
the support for Annotations as Default Driver and require our users to
specify the driver explicitly (which allows us to ask for the path to all
entities).

If you are using the annotations metadata driver as default driver, you
have to add the following lines to your bootstrap code:

    $driverImpl = $config->newDefaultAnnotationDriver(array(__DIR__."/Entities"));
    $config->setMetadataDriverImpl($driverImpl);

You have to specify the path to your entities as either string of a single
path or array of multiple paths
to your entities. This information will be used by all console commands to
access all entities.

Xml and Yaml Drivers work as before!


## New inversedBy attribute

It is now *mandatory* that the owning side of a bidirectional association specifies the
'inversedBy' attribute that points to the name of the field on the inverse side that completes
the association. Example:

    [php]
    // BEFORE (ALPHA4 AND EARLIER)
    class User
    {
        //...
        /** @OneToOne(targetEntity="Address", mappedBy="user") */
        private $address;
        //...
    }
    class Address
    {
        //...
        /** @OneToOne(targetEntity="User") */
        private $user;
        //...
    }
    
    // SINCE BETA1
    // User class DOES NOT CHANGE
    class Address
    {
        //...
        /** @OneToOne(targetEntity="User", inversedBy="address") */
        private $user;
        //...
    }
    
Thus, the inversedBy attribute is the counterpart to the mappedBy attribute. This change
was necessary to enable some simplifications and further performance improvements. We
apologize for the inconvenience.

## Default Property for Field Mappings

The "default" option for database column defaults has been removed. If desired, database column defaults can
be implemented by using the columnDefinition attribute of the @Column annotation (or the approriate XML and YAML equivalents).
Prefer PHP default values, if possible.

## Selecting Partial Objects

Querying for partial objects now has a new syntax. The old syntax to query for partial objects
now has a different meaning. This is best illustrated by an example. If you previously
had a DQL query like this:

    [sql]
    SELECT u.id, u.name FROM User u
    
Since BETA1, simple state field path expressions in the select clause are used to select
object fields as plain scalar values (something that was not possible before).
To achieve the same result as previously (that is, a partial object with only id and name populated)
you need to use the following, explicit syntax:

    [sql]
    SELECT PARTIAL u.{id,name} FROM User u

## XML Mapping Driver

The 'inheritance-type' attribute changed to take last bit of ClassMetadata constant names, i.e.
NONE, SINGLE_TABLE, INHERITANCE_TYPE_JOINED

## YAML Mapping Driver

The way to specify lifecycle callbacks in YAML Mapping driver was changed to allow for multiple callbacks
per event. The Old syntax ways:

    [yaml]
    lifecycleCallbacks:
      doStuffOnPrePersist: prePersist
      doStuffOnPostPersist: postPersist

The new syntax is:

    [yaml]
    lifecycleCallbacks:
      prePersist: [ doStuffOnPrePersist, doOtherStuffOnPrePersistToo ]
      postPersist: [ doStuffOnPostPersist ]

## PreUpdate Event Listeners

Event Listeners listening to the 'preUpdate' event can only affect the primitive values of entity changesets
by using the API on the `PreUpdateEventArgs` instance passed to the preUpdate listener method. Any changes
to the state of the entitys properties won't affect the database UPDATE statement anymore. This gives drastic
performance benefits for the preUpdate event.

## Collection API

The Collection interface in the Common package has been updated with some missing methods
that were present only on the default implementation, ArrayCollection. Custom collection
implementations need to be updated to adhere to the updated interface.