29. Limitations and Known Issues

We try to make using Doctrine2 a very pleasant experience. Therefore we think it is very important to be honest about the current limitations to our users. Much like every other piece of software Doctrine2 is not perfect and far from feature complete. This section should give you an overview of current limitations of Doctrine 2 as well as critical known issues that you should know about.

29.1. Current Limitations

There is a set of limitations that exist currently which might be solved in the future. Any of this limitations now stated has at least one ticket in the Tracker and is discussed for future releases.

29.1.1. Join-Columns with non-primary keys

It is not possible to use join columns pointing to non-primary keys. Doctrine will think these are the primary keys and create lazy-loading proxies with the data, which can lead to unexpected results. Doctrine can for performance reasons not validate the correctness of this settings at runtime but only through the Validate Schema command.

29.1.2. Mapping Arrays to a Join Table

Related to the previous limitation with “Foreign Keys as Identifier” you might be interested in mapping the same table structure as given above to an array. However this is not yet possible either. See the following example:

CREATE TABLE product (
    id INTEGER,
    name VARCHAR,
    PRIMARY KEY(id)
);

CREATE TABLE product_attributes (
    product_id INTEGER,
    attribute_name VARCHAR,
    attribute_value VARCHAR,
    PRIMARY KEY (product_id, attribute_name)
);

This schema should be mapped to a Product Entity as follows:

class Product
{
    private $id;
    private $name;
    private $attributes = array();
}

Where the attribute_name column contains the key and attribute_value contains the value of each array element in $attributes.

The feature request for persistence of primitive value arrays is described in the DDC-298 ticket.

29.1.3. Value Objects

There is currently no native support value objects in Doctrine other than for DateTime instances or if you serialize the objects using serialize()/deserialize() which the DBAL Type “object” supports.

The feature request for full value-object support is described in the DDC-93 ticket.

29.1.4. Cascade Merge with Bi-directional Associations

There are two bugs now that concern the use of cascade merge in combination with bi-directional associations. Make sure to study the behavior of cascade merge if you are using it:

  • DDC-875 Merge can sometimes add the same entity twice into a collection
  • DDC-763 Cascade merge on associated entities can insert too many rows through “Persistence by Reachability”

29.1.5. Custom Persisters

A Persister in Doctrine is an object that is responsible for the hydration and write operations of an entity against the database. Currently there is no way to overwrite the persister implementation for a given entity, however there are several use-cases that can benefit from custom persister implementations:

29.1.6. Persist Keys of Collections

PHP Arrays are ordered hash-maps and so should be the Doctrine\Common\Collections\Collection interface. We plan to evaluate a feature that optionally persists and hydrates the keys of a Collection instance.

Ticket DDC-213

29.1.7. Mapping many tables to one entity

It is not possible to map several equally looking tables onto one entity. For example if you have a production and an archive table of a certain business concept then you cannot have both tables map to the same entity.

29.1.8. Behaviors

Doctrine 2 will never include a behavior system like Doctrine 1 in the core library. We don’t think behaviors add more value than they cost pain and debugging hell. Please see the many different blog posts we have written on this topics:

Doctrine 2 has enough hooks and extension points so that you can add whatever you want on top of it. None of this will ever become core functionality of Doctrine2 however, you will have to rely on third party extensions for magical behaviors.

29.1.9. Nested Set

NestedSet was offered as a behavior in Doctrine 1 and will not be included in the core of Doctrine 2. However there are already two extensions out there that offer support for Nested Set with Doctrine 2:

29.2. Known Issues

The Known Issues section describes critical/blocker bugs and other issues that are either complicated to fix, not fixable due to backwards compatibility issues or where no simple fix exists (yet). We don’t plan to add every bug in the tracker there, just those issues that can potentially cause nightmares or pain of any sort.

See the Open Bugs on Jira for more details on bugs, improvement and feature requests.

29.2.1. Identifier Quoting and Legacy Databases

For compatibility reasons between all the supported vendors and edge case problems Doctrine 2 does NOT do automatic identifier quoting. This can lead to problems when trying to get legacy-databases to work with Doctrine 2.

  • You can quote column-names as described in the Basic-Mapping section.
  • You cannot quote join column names.
  • You cannot use non [a-zA-Z0-9_]+ characters, they will break several SQL statements.

Having problems with these kind of column names? Many databases support all CRUD operations on views that semantically map to certain tables. You can create views for all your problematic tables and column names to avoid the legacy quoting nightmare.

29.2.2. Microsoft SQL Server and Doctrine “datetime”

Doctrine assumes that you use DateTime2 data-types. If your legacy database contains DateTime datatypes then you have to add your own data-type (see Basic Mapping for an example).

29.2.3. MySQL with MyISAM tables

Doctrine cannot provide atomic operations when calling EntityManager#flush() if one of the tables involved uses the storage engine MyISAM. You must use InnoDB or other storage engines that support transactions if you need integrity.

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