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MongoDB Object Persister


Embedding Objects

See example repository for working example

As MongoDB comes with storage engine capable of storing nested structures, Mangan has facility to store objects compositions. Most simple solution for this is to embed sub object in the same document, just like it is created at runtime.

To store sub object in database, use @Embedded annotation on one of object property:

* @Embedded(Address)
public $address = null;

The @Embedded will instruct Mangan to treat property as an object when it is saved or retrieved from MongoDB. Check also repository for example for this documentation page.

By default Mangan will ensure instance when transforming model. To allow null as value, the nullable option can be set to true:

* @Embedded(Address, 'nullable' = true)
public $address = null;

Alternatively, the @Nullable annotation can be used:

* @Embedded(Address)
* @Nullable
public $address = null;

The property marked as @Embedded can store and retrieve object, for example:

$address = new Address;
$address->city = 'Sao Paulo';
$address->street = 'New street';

$company = new Company;
$company->name = 'Maslosoft';
$company->address = $address;

$saved = $company->save();

To retrieve object to same state as it were before saving, use find method. When using Document class, this has convenient active document method for finding it.

Example of finding any document in collection using active document approach:

$company = Company::model()->find();
echo $company->name; // Maslosoft
echo $company->address->city; // Sao Paulo

The same result might be achieved with EntityManager to save and Finder to retrieve:

(new EntityManager($company))->save();
$found = (new Finder(new Company))->find() // Company instance;

The technique with EntityManager and Finder is required when using plain PHP objects or optional when using active documents.