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# CakePHP Datasource Library

This library contains interfaces for implementing Repositories and Entities using any data source,
a class for managing connections to datasources and traits to help you quickly implement the
interfaces provided by this package.

## Repositories

A repository is a class capable of interfacing with a data source using operations such as
`find`, `save` and  `delete` by using intermediate query objects for expressing commands to
the data store and returning Entities as the single result unit of such system.

In the case of a Relational database, a Repository would be a `Table`, which can be return single
or multiple `Entity` objects by using a `Query`.

This library exposes the following interfaces for creating a system that implements the
repository pattern and is compatible with the CakePHP framework:

* `RepositoryInterface` - Describes the methods for a base repository class.
* `EntityInterface` - Describes the methods for a single result object.
* `ResultSetInterface` - Represents the idea of a collection of Entities as a result of a query.

Additionally, this package provides a few traits and classes you can use in your own implementations:

* `EntityTrait` - Contains the default implementation for the `EntityInterface`.
* `QueryTrait` - Exposes the methods for creating a query object capable of returning decoratable collections.
* `ResultSetDecorator` - Decorates any traversable object so it complies with `ResultSetInterface`.


## Connections

This library contains a couple of utility classes meant to create and manage
connection objects. Connections are typically used in repositories for
interfacing with the actual data source system.

The `ConnectionManager` class acts as a registry to access database connections
your application has. It provides a place that other objects can get references
to existing connections. Creating connections with the `ConnectionManager` is
easy:

```php
use Cake\Datasource\ConnectionManager;

ConnectionManager::config('master', [
    'className' => 'MyApp\Connections\CustomConnection',
    'param1' => 'value',
    'param2' => 'another value'
]);

ConnectionManager::config('slave', [
    'className' => 'MyApp\Connections\CustomConnection',
    'param1' => 'different value',
    'param2' => 'another value'
]);
```

When requested, the `ConnectionManager` will instantiate
`MyApp\Connections\CustomConnection` by passing `param1` and `param2` inside an
array as the first argument of the constructor.

Once configured connections can be fetched using `ConnectionManager::get()`.
This method will construct and load a connection if it has not been built
before, or return the existing known connection:

```php
use Cake\Datasource\ConnectionManager;
$conn = ConnectionManager::get('master');
```

It is also possible to store connection objects by passing the instance directly to the manager:

```php
use Cake\Datasource\ConnectionManager;
$conn = ConnectionManager::config('other', $connectionInstance);
```

## Documentation

Please make sure you check the [official API documentation](https://api.cakephp.org/3.x/namespace-Cake.Datasource.html)
