207 lines
8.9 KiB
ReStructuredText
207 lines
8.9 KiB
ReStructuredText
Frequently Asked Questions
|
|
==========================
|
|
|
|
.. note::
|
|
|
|
This FAQ is a work in progress. We will add lots of questions and not answer them right away just to remember
|
|
what is often asked. If you stumble accross an unanswerd question please write a mail to the mailing-list or
|
|
join the #doctrine channel on Freenode IRC.
|
|
|
|
Database Schema
|
|
---------------
|
|
|
|
How do I set the charset and collation for MySQL tables?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
You can't set these values inside the annotations, yml or xml mapping files. To make a database
|
|
work with the default charset and collation you should configure MySQL to use it as default charset,
|
|
or create the database with charset and collation details. This way they get inherited to all newly
|
|
created database tables and columns.
|
|
|
|
Entity Classes
|
|
--------------
|
|
|
|
I access a variable and its null, what is wrong?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
If this variable is a public variable then you are violating one of the criteria for entities.
|
|
All properties have to be protected or private for the proxy object pattern to work.
|
|
|
|
How can I add default values to a column?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Doctrine does not support to set the default values in columns through the "DEFAULT" keyword in SQL.
|
|
This is not necessary however, you can just use your class properties as default values. These are then used
|
|
upon insert:
|
|
|
|
.. code-block:: php
|
|
|
|
class User
|
|
{
|
|
const STATUS_DISABLED = 0;
|
|
const STATUS_ENABLED = 1;
|
|
|
|
private $algorithm = "sha1";
|
|
private $status = self:STATUS_DISABLED;
|
|
}
|
|
|
|
.
|
|
|
|
Mapping
|
|
-------
|
|
|
|
Why do I get exceptions about unique constraint failures during ``$em->flush()``?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Doctrine does not check if you are re-adding entities with a primary key that already exists
|
|
or adding entities to a collection twice. You have to check for both conditions yourself
|
|
in the code before calling ``$em->flush()`` if you know that unique constraint failures
|
|
can occur.
|
|
|
|
In `Symfony2 <http://www.symfony.com>`_ for example there is a Unique Entity Validator
|
|
to achieve this task.
|
|
|
|
For collections you can check with ``$collection->contains($entity)`` if an entity is already
|
|
part of this collection. For a FETCH=LAZY collection this will initialize the collection,
|
|
however for FETCH=EXTRA_LAZY this method will use SQL to determine if this entity is already
|
|
part of the collection.
|
|
|
|
Associations
|
|
------------
|
|
|
|
What is wrong when I get an InvalidArgumentException "A new entity was found through the relationship.."?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
This exception is thrown during ``EntityManager#flush()`` when there exists an object in the identity map
|
|
that contains a reference to an object that Doctrine does not know about. Say for example you grab
|
|
a "User"-entity from the database with a specific id and set a completly new object into one of the associations
|
|
of the User object. If you then call ``EntityManager#flush()`` without letting Doctrine know about
|
|
this new object using ``EntityManager#persist($newObject)`` you will see this exception.
|
|
|
|
You can solve this exception by:
|
|
|
|
* Calling ``EntityManager#persist($newObject)`` on the new object
|
|
* Using cascade=persist on the association that contains the new object
|
|
|
|
How can I filter an association?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Natively you can't filter associations in 2.0 and 2.1. You should use DQL queries to query for the filtered set of entities.
|
|
|
|
I call clear() on a One-To-Many collection but the entities are not deleted
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
This is an expected behavior that has to do with the inverse/owning side handling of Doctrine.
|
|
By definition a One-To-Many association is on the inverse side, that means changes to it
|
|
will not be recognized by Doctrine.
|
|
|
|
If you want to perform the equivalent of the clear operation you have to iterate the
|
|
collection and set the owning side many-to-one reference to NULL aswell to detach all entities
|
|
from the collection. This will trigger the appropriate UPDATE statements on the database.
|
|
|
|
How can I add columns to a many-to-many table?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
The many-to-many association is only supporting foreign keys in the table definition
|
|
To work with many-to-many tables containing extra columns you have to use the
|
|
foreign keys as primary keys feature of Doctrine introduced in version 2.1.
|
|
|
|
See :doc:`the tutorial on composite primary keys for more information<../tutorials/composite-primary-keys>`.
|
|
|
|
|
|
How can i paginate fetch-joined collections?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
If you are issuing a DQL statement that fetches a collection as well you cannot easily iterate
|
|
over this collection using a LIMIT statement (or vendor equivalent).
|
|
|
|
Doctrine does not offer a solution for this out of the box but there are several extensions
|
|
that do:
|
|
|
|
* `DoctrineExtensions <http://github.com/beberlei/DoctrineExtensions>`_
|
|
* `Pagerfanta <http://github.com/whiteoctober/pagerfanta>`_
|
|
|
|
Why does pagination not work correctly with fetch joins?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Pagination in Doctrine uses a LIMIT clause (or vendor equivalent) to restrict the results.
|
|
However when fetch-joining this is not returning the correct number of results since joining
|
|
with a one-to-many or many-to-many association muliplies the number of rows by the number
|
|
of associated entities.
|
|
|
|
See the previous question for a solution to this task.
|
|
|
|
Inheritance
|
|
-----------
|
|
|
|
Can I use Inheritance with Doctrine 2?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Yes, you can use Single- or Joined-Table Inheritance in Doctrine 2.
|
|
|
|
See the documentation chapter on :doc:`inheritance mapping <inheritance-mapping>` for
|
|
the details.
|
|
|
|
Why does Doctrine not create proxy objects for my inheritance hierachy?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
If you set a many-to-one or one-to-one association target-entity to any parent class of
|
|
an inheritance hierachy Doctrine does not know what PHP class the foreign is actually of.
|
|
To find this out it has to execute an SQL query to look this information up in the database.
|
|
|
|
EntityGenerator
|
|
---------------
|
|
|
|
Why does the EntityGenerator not do X?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
The EntityGenerator is not a full fledged code-generator that solves all tasks. Code-Generation
|
|
is not a first-class priority in Doctrine 2 anymore (compared to Doctrine 1). The EntityGenerator
|
|
is supposed to kick-start you, but not towards 100%.
|
|
|
|
Why does the EntityGenerator not generate inheritance correctly?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Just from the details of the discriminator map the EntityGenerator cannot guess the inheritance hierachy.
|
|
This is why the generation of inherited entities does not fully work. You have to adjust some additional
|
|
code to get this one working correctly.
|
|
|
|
Performance
|
|
-----------
|
|
|
|
Why is an extra SQL query executed every time I fetch an entity with a one-to-one relation?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
If Doctrine detects that you are fetching an inverse side one-to-one association
|
|
it has to execute an additional query to load this object, because it cannot know
|
|
if there is no such object (setting null) or if it should set a proxy and which id this proxy has.
|
|
|
|
To solve this problem currently a query has to be executed to find out this information.
|
|
|
|
Doctrine Query Language
|
|
-----------------------
|
|
|
|
What is DQL?
|
|
~~~~~~~~~~~~
|
|
|
|
DQL stands for Doctrine Query Language, a query language that very much looks like SQL
|
|
but has some important benefits when using Doctrine:
|
|
|
|
- It uses class names and fields instead of tables and columns, separating concerns between backend and your object model.
|
|
- It utilizes the metadata defined to offer a range of shortcuts when writing. For example you do not have to specify the ON clause of joins, since Doctrine already knows about them.
|
|
- It adds some functionality that is related to object management and transforms them into SQL.
|
|
|
|
It also has some drawbacks of course:
|
|
|
|
- The syntax is slightly different to SQL so you have to learn and remember the differences.
|
|
- To be vendor independent it can only implement a subset of all the existing SQL dialects. Vendor specific functionality and optimizations cannot be used through DQL unless implemented by you explicitly.
|
|
- For some DQL constructs subselects are used which are known to be slow in MySQL.
|
|
|
|
Can I sort by a function (for example ORDER BY RAND()) in DQL?
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
No, it is not supported to sort by function in DQL. If you need this functionality you should either
|
|
use a native-query or come up with another solution. As a side note: Sorting with ORDER BY RAND() is painfully slow
|
|
starting with 1000 rows.
|
|
|