doctrine2/en/reference/xml-mapping.rst

XML Mapping
===========

The XML mapping driver enables you to provide the ORM metadata in
form of XML documents.

The XML driver is backed by an XML Schema document that describes
the structure of a mapping document. The most recent version of the
XML Schema document is available online at
`http://www.doctrine-project.org/schemas/orm/doctrine-mapping.xsd <http://www.doctrine-project.org/schemas/orm/doctrine-mapping.xsd>`_.
In order to point to the latest version of the document of a
particular stable release branch, just append the release number,
i.e.: doctrine-mapping-2.0.xsd The most convenient way to work with
XML mapping files is to use an IDE/editor that can provide
code-completion based on such an XML Schema document. The following
is an outline of a XML mapping document with the proper xmlns/xsi
setup for the latest code in trunk.

.. code-block:: xml

    <doctrine-mapping xmlns="http://doctrine-project.org/schemas/orm/doctrine-mapping"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://doctrine-project.org/schemas/orm/doctrine-mapping
                        http://doctrine-project.org/schemas/orm/doctrine-mapping.xsd">
    
        ...
    
    </doctrine-mapping>

The XML mapping document of a class is loaded on-demand the first
time it is requested and subsequently stored in the metadata cache.
In order to work, this requires certain conventions:


-  Each entity/mapped superclass must get its own dedicated XML
   mapping document.
-  The name of the mapping document must consist of the fully
   qualified name of the class, where namespace separators are
   replaced by dots (.). For example an Entity with the fully
   qualified class-name "MyProject" would require a mapping file
   "MyProject.Entities.User.dcm.xml" unless the extension is changed.
-  All mapping documents should get the extension ".dcm.xml" to
   identify it as a Doctrine mapping file. This is more of a
   convention and you are not forced to do this. You can change the
   file extension easily enough.

-

.. code-block:: php

    <?php
    $driver->setFileExtension('.xml');

It is recommended to put all XML mapping documents in a single
folder but you can spread the documents over several folders if you
want to. In order to tell the XmlDriver where to look for your
mapping documents, supply an array of paths as the first argument
of the constructor, like this:

.. code-block:: php

    <?php
    $config = new \Doctrine\ORM\Configuration();
    $driver = new \Doctrine\ORM\Mapping\Driver\XmlDriver(array('/path/to/files1', '/path/to/files2'));
    $config->setMetadataDriverImpl($driver);

Example
-------

As a quick start, here is a small example document that makes use
of several common elements:

.. code-block:: xml

    // Doctrine.Tests.ORM.Mapping.User.dcm.xml
    <?xml version="1.0" encoding="UTF-8"?>
    <doctrine-mapping xmlns="http://doctrine-project.org/schemas/orm/doctrine-mapping"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://doctrine-project.org/schemas/orm/doctrine-mapping
                              http://www.doctrine-project.org/schemas/orm/doctrine-mapping.xsd">
    
        <entity name="Doctrine\Tests\ORM\Mapping\User" table="cms_users">
    
            <indexes>
                <index name="name_idx" columns="name"/>
                <index columns="user_email"/>
            </indexes>
    
            <unique-constraints>
                <unique-constraint columns="name,user_email" name="search_idx" />
            </unique-constraints>
    
            <lifecycle-callbacks>
                <lifecycle-callback type="prePersist" method="doStuffOnPrePersist"/>
                <lifecycle-callback type="prePersist" method="doOtherStuffOnPrePersistToo"/>
                <lifecycle-callback type="postPersist" method="doStuffOnPostPersist"/>
            </lifecycle-callbacks>
    
            <id name="id" type="integer" column="id">
                <generator strategy="AUTO"/>
                <sequence-generator sequence-name="tablename_seq" allocation-size="100" initial-value="1" />
            </id>
    
            <field name="name" column="name" type="string" length="50" nullable="true" unique="true" />
            <field name="email" column="user_email" type="string" column-definition="CHAR(32) NOT NULL" />
    
            <one-to-one field="address" target-entity="Address" inversed-by="user">
                <cascade><cascade-remove /></cascade>
                <join-column name="address_id" referenced-column-name="id" on-delete="CASCADE" on-update="CASCADE"/>
            </one-to-one>
    
            <one-to-many field="phonenumbers" target-entity="Phonenumber" mapped-by="user">
                <cascade>
                    <cascade-persist/>
                </cascade>
                <order-by>
                    <order-by-field name="number" direction="ASC" />
                </order-by>
            </one-to-many>
    
            <many-to-many field="groups" target-entity="Group">
                <cascade>
                    <cascade-all/>
                </cascade>
                <join-table name="cms_users_groups">
                    <join-columns>
                        <join-column name="user_id" referenced-column-name="id" nullable="false" unique="false" />
                    </join-columns>
                    <inverse-join-columns>
                        <join-column name="group_id" referenced-column-name="id" column-definition="INT NULL" />
                    </inverse-join-columns>
                </join-table>
            </many-to-many>
    
        </entity>
    
    </doctrine-mapping>

Be aware that class-names specified in the XML files should be
fully qualified.

XML-Element Reference
---------------------

The XML-Element reference explains all the tags and attributes that
the Doctrine Mapping XSD Schema defines. You should read the
Basic-, Association- and Inheritance Mapping chapters to understand
what each of this definitions means in detail.

Defining an Entity
~~~~~~~~~~~~~~~~~~

Each XML Mapping File contains the definition of one entity,
specified as the ``<entity />`` element as a direct child of the
``<doctrine-mapping />`` element:

.. code-block:: xml

    <doctrine-mapping>
        <entity name="MyProject\User" table="cms_users" repository-class="MyProject\UserRepository">
            <!-- definition here -->
        </entity>
    </doctrine-mapping>

Required attributes:


-  name - The fully qualified class-name of the entity.

Optional attributes:


-  table - The Table-Name to be used for this entity. Otherwise the
   Unqualified Class-Name is used by default.
-  repository-class - The fully qualified class-name of an
   alternative ``Doctrine\ORM\EntityRepository`` implementation to be
   used with this entity.
-  inheritance-type - The type of inheritance, defaults to none. A
   more detailed description follows in the
   *Defining Inheritance Mappings* section.

Defining Fields
~~~~~~~~~~~~~~~

Each entity class can contain zero to infinite fields that are
managed by Doctrine. You can define them using the ``<field />``
element as a children to the ``<entity />`` element. The field
element is only used for primitive types that are not the ID of the
entity. For the ID mapping you have to use the ``<id />`` element.

.. code-block:: xml

    <entity name="MyProject\User">
    
        <field name="name" type="string" length="50" />
        <field name="username" type="string" unique="true" />
        <field name="age" type="integer" nullable="true" />
        <field name="isActive" column="is_active" type="boolean" />
        <field name="weight" type="decimal" scale="5" precision="2" />
    </entity>

Required attributes:


-  name - The name of the Property/Field on the given Entity PHP
   class.

Optional attributes:


-  type - The ``Doctrine\DBAL\Types\Type`` name, defaults to
   "string"
-  column - Name of the column in the database, defaults to the
   field name.
-  length - The length of the given type, for use with strings
   only.
-  unique - Should this field contain a unique value across the
   table? Defaults to false.
-  nullable - Should this field allow NULL as a value? Defaults to
   false.
-  version - Should this field be used for optimistic locking? Only
   works on fields with type integer or datetime.
-  scale - Scale of a decimal type.
-  precision - Precision of a decimal type.
-  column-definition - Optional alternative SQL representation for
   this column. This definition begin after the field-name and has to
   specify the complete column definition. Using this feature will
   turn this field dirty for Schema-Tool update commands at all
   times.

Defining Identity and Generator Strategies
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

An entity has to have at least one ``<id />`` element. For
composite keys you can specify more than one id-element, however
surrogate keys are recommended for use with Doctrine 2. The Id
field allows to define properties of the identifier and allows a
subset of the ``<field />`` element attributes:

.. code-block:: xml

    <entity name="MyProject\User">
        <id name="id" type="integer" column="user_id" />
    </entity>

Required attributes:


-  name - The name of the Property/Field on the given Entity PHP
   class.
-  type - The ``Doctrine\DBAL\Types\Type`` name, preferably
   "string" or "integer".

Optional attributes:


-  column - Name of the column in the database, defaults to the
   field name.

Using the simplified definition above Doctrine will use no
identifier strategy for this entity. That means you have to
manually set the identifier before calling
``EntityManager#persist($entity)``. This is the so called
``ASSIGNED`` strategy.

If you want to switch the identifier generation strategy you have
to nest a ``<generator />`` element inside the id-element. This of
course only works for surrogate keys. For composite keys you always
have to use the ``ASSIGNED`` strategy.

.. code-block:: xml

    <entity name="MyProject\User">
        <id name="id" type="integer" column="user_id">
            <generator strategy="AUTO" />
        </id>
    </entity>

The following values are allowed for the ``<generator />`` strategy
attribute:


-  AUTO - Automatic detection of the identifier strategy based on
   the preferred solution of the database vendor.
-  IDENTITY - Use of a IDENTIFY strategy such as Auto-Increment IDs
   available to Doctrine AFTER the INSERT statement has been executed.
-  SEQUENCE - Use of a database sequence to retrieve the
   entity-ids. This is possible before the INSERT statement is
   executed.

If you are using the SEQUENCE strategy you can define an additional
element to describe the sequence:

.. code-block:: xml

    <entity name="MyProject\User">
        <id name="id" type="integer" column="user_id">
            <generator strategy="SEQUENCE" />
            <sequence-generator sequence-name="user_seq" allocation-size="5" initial-value="1" />
        </id>
    </entity>

Required attributes for ``<sequence-generator />``:


-  sequence-name - The name of the sequence

Optional attributes for ``<sequence-generator />``:


-  allocation-size - By how much steps should the sequence be
   incremented when a value is retrieved. Defaults to 1
-  initial-value - What should the initial value of the sequence
   be.

    **NOTE**

    If you want to implement a cross-vendor compatible application you
    have to specify and additionally define the <sequence-generator />
    element, if Doctrine chooses the sequence strategy for a
    platform.


Defining a Mapped Superclass
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sometimes you want to define a class that multiple entities inherit
from, which itself is not an entity however. The chapter on
*Inheritance Mapping* describes a Mapped Superclass in detail. You
can define it in XML using the ``<mapped-superclass />`` tag.

.. code-block:: xml

    <doctrine-mapping>
        <mapped-superclass name="MyProject\BaseClass">
            <field name="created" type="datetime" />
            <field name="updated" type="datetime" />
        </mapped-superclass>
    </doctrine-mapping>

Required attributes:


-  name - Class name of the mapped superclass.

You can nest any number of ``<field />`` and unidirectional
``<many-to-one />`` or ``<one-to-one />`` associations inside a
mapped superclass.

Defining Inheritance Mappings
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

There are currently two inheritance persistence strategies that you
can choose from when defining entities that inherit from each
other. Single Table inheritance saves the fields of the complete
inheritance hierarchy in a single table, joined table inheritance
creates a table for each entity combining the fields using join
conditions.

You can specify the inheritance type in the ``<entity />`` element
and then use the ``<discriminator-column />`` and
``<discriminator-mapping />`` attributes.

.. code-block:: xml

    <entity name="MyProject\Animal" inheritance-type="JOINED">
        <discriminator-column name="discr" type="string" />
        <discriminator-map>
            <discriminator-mapping value="cat" class="MyProject\Cat" />
            <discriminator-mapping value="dog" class="MyProject\Dog" />
            <discriminator-mapping value="mouse" class="MyProject\Mouse" />
        </discriminator-map>
    </entity>

The allowed values for inheritance-type attribute are ``JOINED`` or
``SINGLE_TABLE``.

.. note::

    All inheritance related definitions have to be defined on the root
    entity of the hierarchy.


Defining Lifecycle Callbacks
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can define the lifecycle callback methods on your entities
using the ``<lifecycle-callbacks />`` element:

.. code-block:: xml

    <entity name="Doctrine\Tests\ORM\Mapping\User" table="cms_users">
    
        <lifecycle-callbacks>
            <lifecycle-callback type="prePersist" method="onPrePersist" />
        </lifecycle-callbacks>
    </entity>

Defining One-To-One Relations
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can define One-To-One Relations/Associations using the
``<one-to-one />`` element. The required and optional attributes
depend on the associations being on the inverse or owning side.

For the inverse side the mapping is as simple as:

.. code-block:: xml

    <entity class="MyProject\User">
        <one-to-one field="address" target-entity="Address" mapped-by="user" />
    </entity>

Required attributes for inverse One-To-One:


-  field - Name of the property/field on the entity's PHP class.
-  target-entity - Name of the entity associated entity class. If
   this is not qualified the namespace of the current class is
   prepended. *IMPORTANT:* No leading backslash!
-  mapped-by - Name of the field on the owning side (here Address
   entity) that contains the owning side association.

For the owning side this mapping would look like:

.. code-block:: xml

    <entity class="MyProject\Address">
        <one-to-one field="user" target-entity="User" inversed-by="address" />
    </entity>

Required attributes for owning One-to-One:


-  field - Name of the property/field on the entity's PHP class.
-  target-entity - Name of the entity associated entity class. If
   this is not qualified the namespace of the current class is
   prepended. *IMPORTANT:* No leading backslash!

Optional attributes for owning One-to-One:


-  inversed-by - If the association is bidirectional the
   inversed-by attribute has to be specified with the name of the
   field on the inverse entity that contains the back-reference.
-  orphan-removal - If true, the inverse side entity is always
   deleted when the owning side entity is. Defaults to false.
-  fetch - Either LAZY or FETCH, defaults to LAZY. This attribute
   makes only sense on the owning side, the inverse side *ALWAYS* has
   to use the ``FETCH`` strategy.

The definition for the owning side relies on a bunch of mapping
defaults for the join column names. Without the nested
``<join-column />`` element Doctrine assumes to foreign key to be
called ``user_id`` on the Address Entities table. This is because
the ``MyProject\Address`` entity is the owning side of this
association, which means it contains the foreign key.

The completed explicitly defined mapping is:

.. code-block:: xml

    <entity class="MyProject\Address">
        <one-to-one field="user" target-entity="User" inversed-by="address">
            <join-column name="user_id" referenced-column-name="id" />
        </one-to-one>
    </entity>

Defining Many-To-One Associations
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The many-to-one association is *ALWAYS* the owning side of any
bidirectional association. This simplifies the mapping compared to
the one-to-one case. The minimal mapping for this association looks
like:

.. code-block:: xml

    <entity class="MyProject\Article">
        <many-to-one field="author" target-entity="User" />
    </entity>

Required attributes:


-  field - Name of the property/field on the entity's PHP class.
-  target-entity - Name of the entity associated entity class. If
   this is not qualified the namespace of the current class is
   prepended. *IMPORTANT:* No leading backslash!

Optional attributes:


-  inversed-by - If the association is bidirectional the
   inversed-by attribute has to be specified with the name of the
   field on the inverse entity that contains the back-reference.
-  orphan-removal - If true the entity on the inverse side is
   always deleted when the owning side entity is and it is not
   connected to any other owning side entity anymore. Defaults to
   false.
-  fetch - Either LAZY or FETCH, defaults to LAZY.

This definition relies on a bunch of mapping defaults with regards
to the naming of the join-column/foreign key. The explicitly
defined mapping includes a ``<join-column />`` tag nested inside
the many-to-one association tag:

.. code-block:: xml

    <entity class="MyProject\Article">
        <many-to-one field="author" target-entity="User">
            <join-column name="author_id" referenced-column-name="id" />
        </many-to-one>
    </entity>

The join-column attribute ``name`` specifies the column name of the
foreign key and the ``referenced-column-name`` attribute specifies
the name of the primary key column on the User entity.

Defining One-To-Many Associations
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The one-to-many association is *ALWAYS* the inverse side of any
association. There exists no such thing as a uni-directional
one-to-many association, which means this association only ever
exists for bi-directional associations.

.. code-block:: xml

    <entity class="MyProject\User">
        <one-to-many field="phonenumbers" target-entity="Phonenumber" mapped-by="user" />
    </entity>

Required attributes:


-  field - Name of the property/field on the entity's PHP class.
-  target-entity - Name of the entity associated entity class. If
   this is not qualified the namespace of the current class is
   prepended. *IMPORTANT:* No leading backslash!
-  mapped-by - Name of the field on the owning side (here
   Phonenumber entity) that contains the owning side association.

Optional attributes:


-  fetch - Either LAZY or FETCH, defaults to LAZY.

Defining Many-To-Many Associations
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

From all the associations the many-to-many has the most complex
definition. When you rely on the mapping defaults you can omit many
definitions and rely on their implicit values.

.. code-block:: xml

    <entity class="MyProject\User">
        <many-to-many field="groups" target-entity="Group" />
    </entity>

Required attributes:


-  field - Name of the property/field on the entity's PHP class.
-  target-entity - Name of the entity associated entity class. If
   this is not qualified the namespace of the current class is
   prepended. *IMPORTANT:* No leading backslash!

Optional attributes:


-  mapped-by - Name of the field on the owning side that contains
   the owning side association if the defined many-to-many association
   is on the inverse side.
-  inversed-by - If the association is bidirectional the
   inversed-by attribute has to be specified with the name of the
   field on the inverse entity that contains the back-reference.
-  fetch - Either LAZY or FETCH, defaults to LAZY.

The mapping defaults would lead to a join-table with the name
"User\_Group" being created that contains two columns "user\_id"
and "group\_id". The explicit definition of this mapping would be:

.. code-block:: xml

    <entity class="MyProject\User">
        <many-to-many field="groups" target-entity="Group">
            <join-table name="cms_users_groups">
                <join-columns>
                    <join-column name="user_id" referenced-column-name="id"/>
                </join-columns>
                <inverse-join-columns>
                    <join-column name="group_id" referenced-column-name="id"/>
                </inverse-join-columns>
            </join-table>
        </many-to-many>
    </entity>

Here both the ``<join-columns>`` and ``<inverse-join-columns>``
tags are necessary to tell Doctrine for which side the specified
join-columns apply. These are nested inside a ``<join-table />``
attribute which allows to specify the table name of the
many-to-many join-table.

Cascade Element
~~~~~~~~~~~~~~~

Doctrine allows cascading of several UnitOfWork operations to
related entities. You can specify the cascade operations in the
``<cascade />`` element inside any of the association mapping
tags.

.. code-block:: xml

    <entity class="MyProject\User">
        <many-to-many field="groups" target-entity="Group">
            <cascade>
                <cascade-all/>
            </cascade>
        </many-to-many>
    </entity>

Besides ``<cascade-all />`` the following operations can be
specified by their respective tags:


-  ``<cascade-persist />``
-  ``<cascade-merge />``
-  ``<cascade-remove />``
-  ``<cascade-refresh />``

Join Column Element
~~~~~~~~~~~~~~~~~~~

In any explicitly defined association mapping you will need the
``<join-column />`` tag. It defines how the foreign key and primary
key names are called that are used for joining two entities.

Required attributes:


-  name - The column name of the foreign key.
-  referenced-column-name - The column name of the associated
   entities primary key

Optional attributes:


-  unique - If the join column should contain a UNIQUE constraint.
   This makes sense for Many-To-Many join-columns only to simulate a
   one-to-many unidirectional using a join-table.
-  nullable - should the join column be nullable, defaults to true.
-  on-delete - Foreign Key Cascade action to perform when entity is
   deleted, defaults to NO ACTION/RESTRICT but can be set to
   "CASCADE".

Defining Order of To-Many Associations
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can require one-to-many or many-to-many associations to be
retrieved using an additional ``ORDER BY``.

.. code-block:: xml

    <entity class="MyProject\User">
        <many-to-many field="groups" target-entity="Group">
            <order-by>
                <order-by-field name="name" direction="ASC" />
            </order-by>
        </many-to-many>
    </entity>

Defining Indexes or Unique Constraints
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To define additional indexes or unique constraints on the entities
table you can use the ``<indexes />`` and
``<unique-constraints />`` elements:

.. code-block:: xml

    <entity name="Doctrine\Tests\ORM\Mapping\User" table="cms_users">
    
        <indexes>
            <index name="name_idx" columns="name"/>
            <index columns="user_email"/>
        </indexes>
    
        <unique-constraints>
            <unique-constraint columns="name,user_email" name="search_idx" />
        </unique-constraints>
    </entity>

You have to specify the column and not the entity-class field names
in the index and unique-constraint definitions.