Relations

From RedBean

Contents 1 Relations 2 relatedOne 3 Views (since RedBean 2.0) 4 N:1 Relations 5 Unrelated 6 Using Additional SQL

Relations

RedBean has an incredibly simple system for managing relations among beans. This is best explained by using an example. For instance, imagine we have a bean of type 'book' and we have beans of type 'page'. To put a page in our book we say:

R::associate( $book, $page );

To get all the pages that are part of the book:

R::related( $page, 'book' ); //or..
R::related( $book, 'page' );

To tear a page out of the book:

R::unassociate( $book, $page ); //or $page $book

To tear all the pages out of the book:

R::clearRelations( $book, 'page' );

Or to tear this page out of all books:

R::clearRelations( $page, 'book' );

relatedOne

To find only the first/one related cover

R::relatedOne( $book, 'cover' );

To change to cover of a book:

R::clearRelations( $book, 'cover' );
R::associate( $book, $cover );

Or using a shortcut:

R::clearRelations( $book, 'cover', $cover);

Views (since RedBean 2.0)

Want to fetch all related items at once? Use a view:

R::view('library', 'page,book,author');

You can now query a view called library that has all the information about all pages, books and authors. For instance, to get all pages written by author 'Homerus':

R::getAll('select bodytext from library where name_of_author = ? ', array('Homerus'));

Note that to reference a property originally belonging to another table (name) use: (PROPERTY)_of_(TABLE).

N:1 Relations

RedBeanPHP offers no special functionality to handle N:1 relations, but using foreign key or N:1 associations manually is easy:

$page->book_id = $page->id

And loading a foreign key association is also a no-brainer:

$pages = R::find("page"," book_id = ? ",array($book->id));

Or the other way around:

$book = R::load("book", $page->id );

Unrelated

To find out which beans are NOT related to a specific bean you can use:

R::unrelated( $scandal,  "politician", $sql, $values );

This query will find out for you what politicians have not been involved in the given scandal.

Using Additional SQL

This example demonstrates the use of additional SQL:

$track->orderNum = 1;
R::associate( $album, $track );
//In case you have no WHERE clause, start with 1
R::related( $album, 'track', ' 1 ORDER BY orderNum ' );

$t = R::dispense('person');
$s = R::dispense('person');
$t->role = 'teacher';
$s->role = 'student';
R::associate($t, $s);
R::related($t, 'person', ' role = "student"  ');

You can also use bindings:

R::related( $album, 'track', ' length > ? ', array($seconds) );

And this works with R::relatedOne as well...

R::relatedOne( $album, 'track', ' length > ? ', array($seconds) );

Read more about Associations,Advanced Associations.