Trees

Simple tree

It is built by adding a field of type Parent parent to the model, which stores the id of the parent of the current record. For root records, the value of this field is -1.

An example of simple use of a tree when creating a menu of nested pages.

class Pages extends Model
{
    protected $name = 'Pages menu';
    
    protected $model_elements = [
        ['Active', 'bool', 'active', ['on_create' => true]],
        ['Show in menu', 'bool', 'in_menu', ['on_create' => true]],
        ['Name', 'char', 'name', ['required' => true]],
        ['Prent section', 'parent', 'parent', ['max_depth' => 3]],
        ['Position', 'order', 'order'],
        ['Content', 'text', 'content', ['rich_text' => true]]
    ];
}

Linked tree

To create a structure like catalog -> catalog -> catalog -> product or album -> album -> image, you need to link the model with the parent field to another model so that the final parent of the first model is a foreign key for the records of the other model.

An example of creating a linked tree for a multi-level product catalog.

class Catalogs extends Model 
{
    protected $name = 'Catalog sections';
    
    protected $model_elements = [
        ['Active', 'bool', 'active', ['on_create' => true]],
        ['Name', 'char', 'name', ['required' => true]],
        ['Catalog', 'parent', 'parent', ['parent_for' => 'Products']],
        ['Link', 'url', 'url'],
        ['Position', 'order', 'order']
    ];
}

class Products extends Model 
{
    protected $name = 'Catalog products';
    
    protected $model_elements = [
        ['Active', 'bool', 'active', ['on_create' => true]],
        ['Name', 'char', 'name', ['required' => true]],
        ['Catalog Section', 'enum', 'parent', ['foreign_key' => 'Catalogs',
                                               'is_parent' => true]],
        ['Price', 'int', 'price', ['required' => true]],
        ['Images', 'multi_images','images'],
        ['Description', 'text', 'desc', ['rich_text' => true]],
        ['Position', 'order', 'order']
    ];
}

Special tree methods

Special methods are provided for quick access to parents and descendants in the tree.

• getParents($id) - returns an array of parent records (up to the record with the parent field value equal to -1). In the resulting array, the keys are the record ids, the values ​​are the record names according to the $name_field parameter from the Model setup section.
• getChildren($id) - returns an array of all child records, recursively traversing all tree branches. The resulting array is built similarly to the previous method.

• displayBreadcrumbs($id, $url_first [, $url_field]) - displays the link path to the entry with the passed id. Returns a sequence of html tags in the form: link -> link -> link -> span.

  Input parameters:

  $id of the current entry

  $url_first - the first part of the url, optional parameter

  $url_field - the name of the field that stores the text link for this entry (for constructing a url like /catalog/toys).

  For the pre-installed Pages model, links are automatically built as /page/4 and /contacts (without the first part).

//Search for a record
$catalog = $mv -> catalogs -> find(43);

//Parent records
$parents = $mv -> catalogs -> getParents($catalog -> id);
Debug::pre($parents);

//Child records
$children = $mv -> catalogs -> getChildren($catalog -> id);
Debug::pre($children);

//Reference path for a catalog section
echo $mv -> catalogs -> displayBreadcrumbs($catalog -> id, 'category', 'url');

//Reference path for the catalog product
//The result will be in the form of links: Toys -> Balls -> Red ball
echo $mv -> products -> displayBreadcrumbs($product -> id, 'category');

The listed methods can also be called from within the model object. In the example below, the catalog page is determined based on the passed URL.

class Catalogs extends Model
{
    ...

    //Search for an active entry by URL like '/catalog/23' or '/catalog/tools'
    //Route like '/catalog/*' => 'view-catalog.php' in file 'config/routes.php'

    public function defineCatalog(Router $router)
    {
        $url_parts = $router -> getUrlParts();
        $record = null;

        if(is_numeric($url_parts[1]))
            $record = $this -> find(['id' => $url_parts[1], 'active' => 1]);
        else
            $record = $this -> find(['url' => $url_parts[1], 'active' => 1]);

        if($record !== null)
        {
            $this -> id = $record -> id;
            $this -> parents = $this -> getParents($record -> id);
        }

        return $record;
    }

Recursively build the catalog menu in the Catalogs model.

<?
public function displayCatalogMenu($parent)
{
    //Root section or next deepest section recursively
    $rows = $this -> select(['parent' => $parent, 'active' => 1, 'order->asc' => 'order']);
    $root_path = $this -> root_path.'catalog/';
    $html = '';
    
    foreach($rows as $row)
    {
        //Active menu item
        $active = '';

        //Child elements
        $children = [];
        
        //We search for child elements and set the active item
        if($row['id'] == $this -> id || array_key_exists($row['id'],  $this -> parents))
        {    
            $children = $this -> select(['parent' => $row['id'], 'active' => 1]);
            $active = ' class="active"';
        }
        
        //Forming a link
        $url = $root_path.($row['url'] ? $row['url'] : $row['id']);
        $html .= '<li".$active."><a href="'.$url.'">'.$row['name'].'</a>';
        
        //We output child elements if they exist
        if(count($children) > 0)
            $html .= '<ul>'.$this -> displayCatalogMenu($row['id']).'</ul>';
        
        $html .= '</li>';
    }
    
    return $html;    
}