Maphper

Maphper - A php ORM using the Data Mapper pattern

A work in progress!

Features:

1. Creates database tables on the fly

2. Currently supports database tables but will support XML files, web services even twitter feeds as Data Sources

3. Supports relations between any two data sources

4. Composite primary keys

Maphper takes a simplistic and minimalist approach to data mapping and aims to provide the end user with an intuitive and easy to use API.

The main philosophy of Maphper is that the programmer should deal with sets of data and then be able to manipulate the set and extract other data from it.

Basic Usage

This sets up a Data Mapper that maps to the 'blog' table in a MySQL database. Each mapper has a data source. This source could be anything, a database table, an XML file, a folder full of XML files, a CSV, a Twitter feed, a web service, or anything.

The aim is to give the developer a consistent and simple API which is shared between any of the data sources.

It's then possible to treat the $blogs object like an array.

To set up a Maphper object using a Database Table as its Data Source, first create a standard PDO instance:

$pdo = new PDO('mysql:dbname=maphpertest;host=127.0.0.1', 'username', 'password');

Then create an instance of \Maphper\DataSource\DataBase passing it the PDO instance, name of the table and primary key:

$blogSource = new \Maphper\DataSource\Database($pdo, 'blog', 'id');

Finally create an instance of \Maphper\Maphper and pass it the data source:

$blogs = new \Maphper\Maphper($blogSource);

You can loop through all the blogs using:

foreach ($blogs as $blog) {
  echo $blog->title . '<br />';
}

Any fields from the database table (or xml file, web service, etc) will be available in the $blog object

Alternatively you can find a specific blog using the ID

echo $blogs[142]->title;

Which will find a blog with the id of 142 and display the title.

Filters

Maphper supports filtering the data:

//find blogs that were posted on a specific date
$filteredBlogs = $blogs->filter(['date' => '2014-04-09']);

//this will only retrieve blogs that were matched by the filter
foreach ($filteredBlogs as $blog) {
	echo $blog->title;
}

Filters can be extended and chained together:

//find blogs that were posted with the title "My Blog" by the author with the id of 7
$filteredBlogs = $blogs->filter(['title' => 'My Blog'])->filter(['authorId' => 7]);

//this will only retrieve blogs that were matched by both filters
foreach ($filteredBlogs as $blog) {
	echo $blog->title;
}

As well as filtering there are both sort() and limit() methods which can all be chained:

foreach ($blogs->filter(['date' => '2014-04-09']) as $blog) {
  echo $blog->title;
}

To find the latest 5 blogs you could use:

foreach ($blogs->limit(5)->sort('date desc') as $blog) {
  echo $blog->title;
}

Like any array, you can count the total number of blogs using:

echo 'Total number of blogs is ' . count($blogs);

This will count the total number of blogs in the table. You can also count filtered results:

//Count the number of blogs in category 3
echo count($blogs->filter(['categoryId' => 3]);

Saving Data

To save an object back into the data mapper, simply create an instance of stdClass:

$pdo = new PDO('mysql:dbname=maphpertest;host=127.0.0.1', 'username', 'password');
$blogSource = new \Maphper\DataSource\Database($pdo, 'blog', 'id');
$blogs = new \Maphper\Maphper($blogSource);


$blog = new stdClass;

$blog->title = 'My Blog Title';
$blog->content = 'This is my first blog entry';

//Store the blog using the next available ID
$blogs[] = $blog;

echo 'The new blog ID is :' . $blog->id;

Alternatively, you can write a record to a specific ID by specifying the index:

$blog = new stdClass;

$blog->title = 'My Blog Title';
$blog->content = 'This is my first blog entry';

//Store the blog with the primary key of 7
$blogs[7] = $blog;

Note: The behaviour of this is identical to setting the id property on the $blog object directly:

$blog = new stdClass;

$blog->id = 7;
$blog->title = 'My Blog Title';
$blog->content = 'This is my first blog entry';

//Store the blog with the primary key of 7
$blogs[] = $blog;

Relationships

If there was an Author table which stored information about blog authors, it could be set up in a similar way:

$authorSource = new \Maphper\DataSource\Database($pdo, 'author', 'id');
$authors = new \Maphper\Maphper($authorSource);

This could be used similarly:

$author = $authors[123];
echo $author->name;

Once both the blogs and authors mappers have been defined, you can create a relationship between them.

This is a one-to-one relationship (one blog has one author) and can be achieved using the addRelation method on the blog mapper:

//Create a one-to-one relationship between blogs and authors (a blog can only have one author)
$relation = new \Maphper\Relation(\Maphper\Relation::ONE, $authors, 'authorId', 'id');
$blogs->addRelation('author', $relation);

\Maphper\Relation::ONE tells Maphper that it's a one-to-one relationship

The second parameter, $authors tells Maphper that the relationship is to the $authors mapper (in this case, the author database table, although you can define relationships between different data types)

'authorId' is the field in the blog table that's being joined from

'id' is the field in the author table that's being joined to

After the relation is constructed it can be added to the blog mapper using:

$blogs->addRelation('author', $relation);

The first parameter (here: 'author') is the name of the property the related data will be available under. So any object retrieved from the $blogs mapper will now have an 'author' property that contains the author of the blog and can be used like this:

foreach ($blogs as $blog) {
  echo $blog->title . '<br />';
  echo $blog->author->name . '<br />';
}

Similarly, you can define the inverse relation between authors and blogs. This is a one-to-many relationship because an author can post more than one blog.

//Create a one-to-one relationship between blogs and authors (a blog can only have one author)
//Joining from the 'id' field in the authors mapper to the 'authorId' field in the blogs mapper
$relation = new \Maphper\Relation(\Maphper\Relation::MANY, $blogs, 'id', 'authorId');
$authors->addRelation('blogs', $relation);

This is creating a relationship between authors and blogs using the id field in the $authors mapper to the authorId field in the $blogs mapper and making a blogs property available in an object returned by the $authors mapper;

//Count all the blogs by the author with id 5
$authors[4]->name . ' has posted ' .  count($authors[4]->blogs)  . ' blogs:<br />';

//Loop through all the blogs created by the author with id 4
foreach ($authors[4]->blogs as $blog) {
    echo $blog->title . '<br />';
}

Saving values with relationships

Once you have created your mappers and defined the relationships between them, you can write to the relationships directly. For example:

$authors = new \Maphper\Maphper(new \Maphper\DataSource\Database($pdo, 'author'));
$blogs = new \Maphper\Maphper(new \Maphper\DataSource\Database($pdo, 'blog', 'id'));
$blogs->addRelation('author', new \Maphper\Relation(\Maphper\Relation::ONE, $authors, 'authorId', 'id'));


$blog = new stdClass;
$blog->title = 'My First Blog';
$blog->date = new \DateTime();
$blog->author = new stdClass;
$blog->author->name = 'Tom Butler';

$blogs[] = $blog;

This will save both the $blog object into the blog table and the $author object into the author table as well as setting the blog record's authorId column to the id that was generated.

You can also do the same with one-to-many relationships:

$authors = new \Maphper\Maphper(new \Maphper\DataSource\Database($pdo, 'author'));
$blogs = new \Maphper\Maphper(new \Maphper\DataSource\Database($pdo, 'blog', 'id'))

$authors->addRelation('blogs', new \Maphper\Relation(\Maphper\Relation::MANY, $blogs, 'id', 'authorId'));


//Find the author with id 4
$author = $authors[4]; 


$blog = new stdClass;
$blog->title = 'My New Blog';
$blog->date = new \DateTime();

//Add the blog to the author. This will save to the database at the point it's added 
$author->blogs[] = $blog;

Composite Primary Keys

Maphper allows composite primary keys. For example, if you had a table of products you could use the manufacturer id and manufacturer part number as primary keys (Two manufacuterers may use the same part number!)

To do this, define the data source with an array for the primary key:

$pdo = new PDO('mysql:dbname=maphpertest;host=127.0.0.1', 'username', 'password');
$productSource = new \Maphper\DataSource\Database($pdo, 'products', ['manufacturerId', 'partNumber']);
$products = new \Maphper\Maphper($productSource);

Once you have defined the source to use multiple keys, you can treat the $products variable like a two dimensional array:

//Get the product with manufacturerId 7 and partNumber AC294
echo $products[7]['AC294']->name;

To write data using composite keys, you simply write an object to a specified index:

$pdo = new PDO('mysql:dbname=maphpertest;host=127.0.0.1', 'username', 'password');
$productSource = new \Maphper\DataSource\Database($pdo, 'products', ['manufacturerId', 'partNumber']);
$products = new \Maphper\Maphper($productSource);

$product = new stdClass;
$product->name 'Can of cola';

$products[1]['CANCOLA'] = $product;

Dates

Maphper uses the inbuilt \DateTime class from PHP to store and search by dates:

$blog = new stdClass;
$blog->title = 'A blog entry';

//You can construct the date object using any of the formats availble in the inbuilt PHP datetime class
$blog->date = new \DateTime('2015-11-14');

This can also be used in filters:

//Find all blogs posted on 2015-11-14
$maphper->filter(['date' => new \DateTime('2015-11-14)]);

It is recommended to use the DateTime class rather than passing the date value as a string as not all mappers will use the same internal date format

Automatic Database Table creation/amendment

Maphper can be instructed to automatically construct database tables. This is done on the fly, you just need to tell maphper you want to use this behaviour. When you construct your Database Data source, set editmode to true:

$pdo = new PDO('mysql:dbname=maphpertest;host=127.0.0.1', 'username', 'password');
$blogs = new \Maphper\DataSource\Database($pdo, 'blogs', ['id'], ['editmode' => true]);

This should ony be enabled during development. In production you should set this to false.

User defined classes for objects

It's possible to use your own classes instead of stdClass for any object managed by Maphper. This object will automatically have its properties set when it is created.

For example, if you had a product class:

class Product {
	private $name;
	private $price;
	
	const TAX_RATE = 0.2;
	
	public function getTax() {
		return $this->price * self::TAX_RATE;
	}
	
	public function getTotalPrice() {
		return $this->price + $this->getTax();
	}
}

You can instruct Maphper to use this class using the 'resultClass' option in the $options array when creating the DataSource instance:

$dataSource = new \Maphper\DataSource\Database($pdo, 'product', 'id', ['resultClass' => 'Product']);
$products = new \Maphper\Maphper($dataSource);

$product = $products[123];


echo get_class($product); //"Product" instance

//And as expected, the methods from Product are available:
$tax = $product->getTax();
$total = $product->getTotalPrice();

Private properties are both saved and loaded as any normal properties.

Factory creation for new objects

Sometimes your result class may have dependencies. In this case, you can specify a method rather than a class name to act as a factory. Consider the following:

class TaxCalculator {
	const TAX_RATE = 0.2;
	
	public function getTax($price) {
		return $price * self::TAX_RATE;
	}
}

class Product {
	private $name;
	private $price;
	private $taxCalculator;
	
	
	public function __construct(TaxCalculator $taxCalculator) {
		$this->taxCalculator = $taxCalculator;
	}	
	
	public function getTax() {
		return $this->taxCalculator->getTax($this->price);
	}
	
	public function getTotalPrice() {
		return $this->price + $this->getTax();
	}
}

In this case using:

$dataSource = new \Maphper\DataSource\Database($pdo, 'product', 'id', ['resultClass' => 'Product']);

Will error, because when an instance of Product is constructed, Maphper isn't smart enough to guess that a TaxCalculator instance is required as a constructor argument. Instead, you can pass a closure that returns a fully constructed object:

$taxCalculator = new TaxCalculator;

$dataSource = new \Maphper\DataSource\Database($pdo, 'product', 'id', ['resultClass' => function() use ($taxCalculator) {
	return new Product($taxCalculator);
}]);

Alternatively if you want considerably more control over the dependencies you can use a Dependency Injection Container such as Dice:

$dice = new \Dice\Dice;

$dataSource = new \Maphper\DataSource\Database($pdo, 'product', 'id', ['resultClass' => function() use ($dice) {
	return $dice->create('Product');
}]);