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Cursor

This Cursor class is an abstract foundation of an Active Record implementation, that is used by all F3 Data Mappers.

Have a look at the SQL Mapper, Mongo Mapper or JIG Mapper page to get to know about how to create and use them with their own functions and the following described below.

Namespace: \DB
File location: lib/db/cursor.php

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Cursor Methods

The following methods are available to all Data Mappers. Even if the filter and option syntax may differ from one mapper to another, the behaviour of these functions are the same. So assume you have this set of data in your DB table when you'll be reading the examples below.

ID	title	text	author
1	F3 for the win	Use It Now!	49
2	Once upon a time	there was a dragon.	2
3	Barbar the Foo	foo bar	25
4	untitled	lorem ipsum	8

load

Map to first record that matches criteria

array|FALSE load ( [ string|array $filter = NULL [, array $options = NULL [, int $ttl = 0 ]]] )

The load method hydrates the mapper object with records. You can define a $filter to load only records that matches your criteria.

It uses find() to load records and makes the first record (mapper object) that matches criteria the active record. Additional records that match the same criteria can be made the active record by moving the cursor pointer (i.e. with skip()).

You can find detailed descriptions about the $filter and $option syntax on the mapper specific pages: Jig Mapper, Mongo Mapper and SQL Mapper.

The $ttl argument, when specified in seconds, allows you to cache the result of the mapper load, provided a CACHE system is activated.

Let's start with a simple example where we do not specify any filter, so the first record will be loaded:

$mapper->load();  // by default, loads the 1st record and makes it active
echo $mapper->title; // displays 'F3 for the win'

The Cursor class extends the Magic class. This means you are able to access your data fields like you do it with any object properties and array keys:

echo $mapper->title; // 'F3 for the win'
echo $mapper['text']; // 'Use It Now!'
echo $mapper->get('author'); // 49

next

Map to next record

mixed next ( )

When a mapper object is hydrated, its internal cursor pointer points to a single record. To move the pointer forward to the next record, you use this method.

$mapper->load();
echo $mapper->title; // 'F3 for the win'
$mapper->next();
echo $mapper->title; // 'Once upon a time'

Internally, the Cursor class fetches all records from the underlying database matching the $filter specified when calling load(). Any attempt to navigate to the next, previous, first or last record will just move the internal pointer, thereby reducing disk I/O.

prev

Map to previous record

mixed prev ( )

first

Map to first record in cursor

mixed first ( )

last

Map to last record in cursor

mixed last ( )

skip

Map to n-th record relative to current cursor position

mixed skip ( [ int $ofs = 1 ] )

dry

Return TRUE if the current cursor position is not mapped to any record

bool dry ( )

This is some kind of "empty" function. It returns TRUE if the cursor is not mapped to any database record, even if records have been loaded.

The next example snippet loops through all loaded records and stops when the current cursor pointer is dry (not hydrated) :

$mapper->load();  // by default, loads the 1st record

while ( !$mapper->dry() ) {  // gets dry when we passed the last record
	echo $mapper->title;
	// moves forward even when the internal pointer is on last record
	$mapper->next();
}

findone

Return first record (mapper object) that matches criteria

object|FALSE findone ( [ string|array $filter = NULL [, array $options = NULL [, int $ttl = 0 ]]] )

Use this method if you only want to process a single entity in your business logic. It is helpful to only load that single record.

See the load() method for details regarding the parameters.

paginate

Return a subset of records with additional pagination information

array paginate ( [ int $pos = 0 [, int $size = 10 [, string|array $filter = NULL [, array $options = NULL [, int $ttl = 0]]]]] )

This method returns an array containing a subset of records that are matching the $filter criterias, the total number of records found, the specified limit $size, the number of subsets available and the actual subset position.

For example:

// page 1
$result = $mapper->paginate(0, 3);
/*
array(4) {
	["subset"] => array(3) {
		[0] => mapper object, #ID: 1, title: F3 for the win
		[1] => mapper object, #ID: 2, title: Once upon a time
		[2] => mapper object, #ID: 3, title: Barbar the Foo
	}
	["total"] => int(4)
	["limit"] => int(3)
	["count"] => float(2)
	["pos"] => int(0)
}
*/

// page 2
$result = $mapper->paginate(1, 3);
/*
array(4) {
	["subset"] => array(1) {
		[0] => mapper object, #ID: 4, title: untitled
	}
	["total"] => int(4)
	["limit"] => int(3)
	["count"] => float(2)
	["pos"] => int(1)
}
*/

The subset key contains an array of mapper objects returned from find(). total is the sum of all records for all pages. limit holds the same value as the size input parameter to the call. count is the number of subsets/pages available. pos gives you the current subset cursor position ( it's the page number - 1).

loaded

Return the count of records loaded

int loaded ( )

save

Save mapped record

mixed save ( )

This method saves data to the database. The Cursor class automatically determines if the record should be updated or inserted as a new entry, based on the return value of dry.

erase

Delete current record

int|bool erase ( )

reset

Reset/dehydrate the cursor

NULL reset ( )

Event handlers

All Cursor derivatives offer the possibility to intercept the processing on certain events through custom functions. This gives you the opportunity to add some validation, sanitation or more complex business logic. See the following described methods to get an overview of possible events you may hook into.

Notice: If you extend the mapper and try to read or modify mapper fields (especially those that also exist as class property) with magic getter/setter within those event handlers, you will get unpredictable behaviours or run into errors.

The simple solution to this is to stick to the usage of the get or set methods from within the child class. These are safe to use and won't override protected properties.

class Model extends \DB\SQL\Mapper {
    function __construct(){
        parent::__construct(\Base::instance()->get('DB'),'test_model');
        $this->beforeinsert(function($self){
            $self->source='bar'; // fails due to protected property named 'source'
            $self->set('source','bar'); // works - just use the setter directly
        });
}}

Refer to the FatFree GitHub Issue #697 for more details.

onload

Define a hook to the onload event

The hook will be executed everytime the mapper is loaded. For example, it will be executed once after a call to load(), next() or prev(), but also will be executed for every mapper returned by find().

callable onload ( callable $func )

The hook function takes 1 argument : the mapper object. E.g:

$mapper->onload(function($self){
  //do something
});

beforeinsert, afterinsert

Define hooks to the beforeinsert and afterinsert events

The beforeinsert hook will be executed just before any INSERT statement and is able to abort the event by returning false.

The afterinsert hook will be executed right after any issued INSERT statement.

callable beforeinsert ( callable $func )
callable afterinsert ( callable $func )

Each hook function takes 2 arguments : the mapper object and the primary key(s) value(s). E.g:

$mapper->beforeinsert(function($self,$pkeys){
  //do something before inserting
});
$mapper->afterinsert(function($self,$pkeys){
  //do something after inserting
});

beforeupdate, afterupdate

Define hooks to the beforeupdate and afterupdate events

The beforeupdate hook will be executed just before any UPDATE statement and is able to abort the event by returning false.

The afterupdate hook will be executed right after any issued UPDATE statement.

callable beforeupdate ( callable $func )
callable afterupdate ( callable $func )

Each hook function takes 2 arguments : the mapper object and the primary key(s) value(s). E.g:

$mapper->beforeupdate(function($self,$pkeys){
  //do something before updating
});
$mapper->afterupdate(function($self,$pkeys){
  //do something after updating
});

beforesave, aftersave

Define hooks to the beforeinsert, beforeupdate, afterinsert and afterupdate events

The beforesave hook will be executed just before any INSERT or UPDATE statement and is able to abort the event by returning false.

The aftersave hook will be executed right after any issued INSERT or UPDATE statement.

callable beforesave ( callable $func )
callable aftersave ( callable $func )

Each hook function takes 2 arguments : the mapper object and the primary key(s) value(s). E.g:

$mapper->beforesave(function($self,$pkeys){
  //do something before inserting or updating
});
$mapper->aftersave(function($self,$pkeys){
  //do something after inserting or updating
});

beforeerase, aftererase

Define hooks to the beforeerase and aftererase events

The beforerase hook will be executed just before any DELETE statement and is able to abort the event by returning false.

The aftererase hook will be executed right after any issued DELETE statement.

callable beforeerase ( callable $func )
callable aftererase ( callable $func )

Each hook function takes 2 arguments : the mapper object and the primary key(s) value(s). E.g:

$mapper->beforeerase(function($self,$pkeys){
  //do something before deleting
});
$mapper->aftererase(function($self,$pkeys){
  //do something after deleting
  echo 'the id of the deleted row was '.$pkeys['id'];
});

oninsert, onupdate, onerase

Provided for backwards compatibility, they are aliases to respectively afterinsert(), afterupdate() and aftererase().

Abstract Methods

The following methods must be implemented by all extending mapper classes to work properly.

find

Return records (array of mapper objects) that match criteria

array find ( [ string|array $filter = NULL [, array $options = NULL [, $ttl = 0 ]]] )

See the load() method for details regarding the parameters.

insert

Insert a new record

array insert ( )

update

Update the current record

array update ( )