Data Core¶

Within web-framework data and database interaction is abstracted where possible. With a little bit of code you can make simple and more complex object types by just providing an ID or another identifier.

The core library has two base classes to build from:

DataCore, an object abstraction that represents a row from a table
FactoryCore, a factory abstraction that understands how to work with DataCore objects

DataCore¶

The base data abstraction is done with DataCore. By just specifying the table_name and base_fields you can already easily instantiate objects based on data in the database.

If we have a table persons in our database, with fields like name, address and country, we can easily encapsulate this table with a DataCore abstraction. Let’s create includes/persons.inc.php to construct the Person class.

<?php
class Person extends DataCore
{
    static protected $table_name = 'persons';
    static protected $base_fields = array('name', 'email', 'country');
};
?>

Note

For encapsulation with DataCore, each table needs a column named id with unique, as primary key values.

Our Person object now has basic capabilities. While we can instantiate an DataCore object with new, this is not advised for multiple reasons. You should use DataCore::get_object_by_id() and others instead. The main reason is that this gracefully handles non-existing IDs (returning false), but also allows intermediate caching and transformations.

So if we instantiate a Person (using our global database information), we can take actions, like these:

<?php
// Retrieve person with id 5
$person = Person::get_object_by_id(5);

// Retrieve base fields as object parameters
echo 'Name: '.$person->name.PHP_EOL;

// Update this Person's country
$result = $person->update(array('country' => 'Belgium'));
WF::verify($result !== false, 'Failed to update person');
?>

Note

What is WF::verify()? WF::verify() is like assert(). It is used to guard code paths that should never occur, unless something is really wrong. But unlike assert() our WF::verify() cannot be silently ignored due to PHP settings. For a secure-by-default platform, we want to make sure those guards are always there. In addition it can show a debug trace, debug info and e-mail you in case a verify gate fails. In most cases you will use $this->verify() instead, when you work with code in objects.

Complex objects¶

There are a lot of cases where you don’t just need to encapsulate a single row from a single table, but data from other tables is required as well. Let’s consider that our Person can also own one or more vehicles. We can easily make sure that those vehicles are populated directly at instantiation of a Person.

Let’s first create our Vehicle class in includes/vehicles.inc.php:

<?php
class Vehicle extends DataCore
{
    static protected $table_name = 'vehicles';
    static protected $base_fields = array('type', 'brand', 'color');
};
?>

Now we include this file at the top of includes/persons.inc.php:

require_once(WF::$site_includes.'vehicles.inc.php');

class Person extends DataCore
<snip>

And we’ll add a method called fill_complex_fields() in our Person class:

function fill_complex_fields()
{
    $this->vehicles = Vehicles::get_objects(0, -1,
                                   array('owner_id' => $this->id));
}

fill_complex_fields() is immediately called in the constructor after all base fields have been loaded.

Keep in mind that Person->fill_complex_fields() runs on every instantiation. In most cases you want to be able to instantiate a bare Person class as well. So it would be better to just implement a Person->get_vehicles() (with optional caching) instead:

protected $vehicles = null;
function get_vehicles()
{
    if ($this->vehicles === null)
        $this->vehicles = Vehicles::get_objects(0, -1, array('owner_id' => $this->id));

    return $this->vehicles;
}

Object Documentation¶

DataCore Object¶

class DataCore¶

An object abstration that represents a single row from a table.

protected static property $table_name¶: The name of the table in your database

protected static property $base_fields¶: An array with fields that should always be loaded into the object

get_base_fields()¶: Retrieve all raw database fields

get_field($field)¶

Retrieve a non-base-field for the object

Parameters

$field (string) – The field name in the table

update($data)¶

Update fields in the database

Parameters

$data (array) – Array with field names and values to store

update_field($field, $value)¶

Update a single field

Parameters

$field (string) – Field to update
$value – Value to store

decrease_field($field, $value = 1, $minimum = false)¶

Decrease the value of a field

Parameters

$field (string) – Field to update
$value – Decrease by this value
$minimum – If set, value will not reduce below this minimu,

increase_field($field, $value = 1)¶

Increase the value of a field

Parameters

$field (string) – Field to update
$value – Increase by this value

delete()¶: Delete this item

static create($fields)¶

Create a new Database entry with these fields

Parameters

$fields (array) – Array of all (required) database fields for this table

static exists($id)¶

Check if an object with that id exists.

Parameters

$id (int) – ID of the object to check

static count_objects($filter)¶

Count the number of entries that match the filter

Parameters

$filter (array) – Array of fields that should match

static get_object_by_id($id)¶

Retrieve an object by id

Parameters

$id (array) – The id of the object to retrieve

static get_object($filter)¶

Retrieve a single object based on a filter array. Fails if more than one entries match.

Parameters

$filter (array) – Array of fields that should match

static get_object_info($filter)¶

Retrieve a single object’s get_info() based on a filter array. Fails if more than one entries match.

Parameters

$filter (array) – Array of fields that should match

static get_object_data($data_function, $filter)¶

Retrieve a single object’s data via the data_function specified based on a filter array. Fails if more than one entries match.

Parameters

$data_function (array) – Data function to call
$filter (array) – Array of fields that should match

static get_object_info_by_id($id)¶

Retrieve a single object’s get_info() based on id.

Parameters

$id (array) – The id of the object to retrieve.

static get_object_data_by_id($data_function, $id)¶

Retrieve a single object’s data via the data_function specified.

Parameters

$data_function (array) – Data function to call
$id (array) – The id of the object to retrieve

static get_objects($offset, $results, $filter, $order)¶

Retrieve an array of objects based on a filter array.

Parameters

$offset (array) – Start offset for paging
$results (array) – Amount of objects for paging
$filter (array) – Array of fields that should match
$order (array) – String of SQL order

static get_objects_info($offset, $results, $filter, $order)¶

Retrieve an array filled with objects’ get_info() based on a filter array.

Parameters

$offset (array) – Start offset for paging
$results (array) – Amount of objects for paging
$filter (array) – Array of fields that should match
$order (array) – String of SQL order

static get_objects_data($data_function, $offset, $results, $filter, $order)¶

Retrieve an array filled fill objects’ data via the data_function specified based on a filter array.

Parameters

$data_function (array) – Data function to call
$offset (array) – Start offset for paging
$results (array) – Amount of objects for paging
$filter (array) – Array of fields that should match
$order (array) – String of SQL order