Doctrine 2 schema update produces MySQL errno 150, Foreign Key constraint - symfony

Question

When using Doctrine ORM in Symfony2, I have the following tables generated from three different entities, of which accessory has two foreign key constraints (marked A and B below).
describe publication;
+-------------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| kid | varchar(10) | NO | | NULL | |
| title | varchar(255) | NO | | NULL | |
| title_canonical | varchar(255) | NO | | NULL | | <- A
| created | datetime | NO | | NULL | |
| modified | datetime | NO | | NULL | |
+-------------------+--------------+------+-----+---------+----------------+
describe accessory;
+-------------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| publication_title | varchar(255) | YES | | NULL | | <- A
| index_id | int(11) | NO | | NULL | |
| index_alias | varchar(255) | NO | | NULL | |
| value | longtext | NO | | NULL | |
| attribute_name | varchar(255) | YES | | NULL | | <- B
+-------------------+--------------+------+-----+---------+----------------+
describe attribute;
+-------------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(255) | NO | | NULL | |
| name_canonical | varchar(255) | NO | | NULL | | <- B
| parameter | varchar(16) | NO | | NULL | |
+-------------------+--------------+------+-----+---------+----------------+
The foreign keys are mapped with annotations:
Publication.php
/**
* #ORM\OneToMany(targetEntity="Accessory", mappedBy="publication")
*/
protected $accessories;
Accessory.php
/**
* #ORM\ManyToOne(targetEntity="Publication", inversedBy="accessories")
* #ORM\JoinColumn(name="publication_title", referencedColumnName="title_canonical")
*/
protected $publication;
/**
* #ORM\ManyToOne(targetEntity="Attribute", inversedBy="accessories")
* #ORM\JoinColumn(name="attribute_name", referencedColumnName="name_canonical")
*/
protected $attribute;
Attribute.php
/**
* #ORM\OneToMany(targetEntity="Accessory", mappedBy="attribute")
*/
protected $accessories;
but upon running php app/console doctrine:schema:update --force I got this exception
[Doctrine\DBAL\DBALException]
An exception occurred while executing 'ALTER TABLE accessory ADD CONSTRAINT FK_A1B1251CCEE83EE7 FOREIGN KEY (publication_title) REFERENCES publication (title_canonical)':
SQLSTATE[HY000]: General error: 1005 Can't create table 'publicationsapp.#sql-2a3c_2828' (errno: 150)
So I ran php app/console doctrine:schema:update --dump-sql
ALTER TABLE accessory ADD CONSTRAINT FK_A1B1251CCEE83EE7 FOREIGN KEY (publication_title) REFERENCES publication (title_canonical);
ALTER TABLE accessory ADD CONSTRAINT FK_A1B1251C5CBDA8E FOREIGN KEY (attribute_name) REFERENCES attribute (name_canonical);
CREATE INDEX IDX_A1B1251CCEE83EE7 ON accessory (publication_title);
CREATE INDEX IDX_A1B1251C5CBDA8E ON accessory (attribute_name);
What's the correct way to resolve this? Should I edit the tables manually or with Doctrine?
Based on what I've read about errno 150, the foreign column needs to be indexed, but can't Doctrine handle this automatically?

Answer 1

One could add unique=true to both $nameCanonical and $titleCanonical properties or whichever columns are referenced by the foreign key. Then drop and run the schema update command to recreate the tables.
In the case of $titleCanonical
/**
* #var string
*
* #ORM\Column(name="title_canonical", type="string", length=255, unique=true)
*/
private $titleCanonical;
But ideally with Doctrine, the foreign keys should be referenced to the other table's primary key to make it valid.