Check if it has a related item before deleting in CakePHP

I'd like to check to make sure that before a Venue is deleted, it doesn't have any Events tied t开发者_运维问答o it.

Venue hasMany Event
Event belongsTo Venue

I believe I'd do this in a beforeDelete function in my Venue model - but - beyond that, I'm not sure how to check for Events... do I have to include access to the Event model somehow? If it fails, is there a way to return a specific error message like validation allows? Or... do I do this in the validation itself?

This should do what you need. It will check for a count of events before deleting a venue, then if the count is greater than 0 it will return false, preventing the deletion. Else, it will delete if there are no events associated.

// using app/models/venue.php
// In the following example, do not let a venue delete if it still contains events.
// A call of $this->Venue->delete($id) from VenueController.php has set $this->id .
// Assuming 'Venue hasMany Event', we can access $this->Event in the model.
function beforeDelete(){
    $count = $this->Event->find("count", array("conditions" => array("venue_id" => $this->id)));
    if ($count == 0) {
        return true;
    } else {
        return false;
    }
}

Or you can do this:

In your model add this method

function hasEvents($venue_id){
    $count = $this->Event->find("count", array("conditions" => array("venue_id" => $venue_id)));
    if ($count == 0) {
        return false;
    } else {
        return true;
    }
}

In your controller

if($this->Venue->hasEvents($venue_id)){
    //display error message that you cannot delete because venue has events
} else {
    $this->Venue->delete($venue_id);
}

use this behavior:

<?php
/**
 * Prevent deletion if child record found
 *
 * @author    Nik Chankov
 * @url    http://nik.chankov.net
 */
class HasChildrenBehavior extends ModelBehavior {
    /**
     * Empty Setup Function
    */
    function setup(&$model) {
        $this->model = $model;
    }

    /**
     * Run the check and cancel the deletion if child is found
     * @access public
     */
    function beforeDelete(){
        if(isset($this->model->hasMany)){
            foreach($this->model->hasMany as $key=>$value){
                $childRecords = $this->model->{$key}->find('count', array('conditions'=>array($value['foreignKey']=>$this->model->id)));
                if($childRecords > 0){
                    return false;
                }
            }
        }
        //Checking habtm relation as well, thanks to Zoltan
        if(isset($this->model->hasAndBelongsToMany)){
            foreach($this->model->hasAndBelongsToMany as $key=>$value){
                $childRecords = $this->model->{$key}->find('count', array('conditions'=>array($value['foreignKey']=>$this->model->id)));
                if($childRecords > 0){
                    return false;
                }
            }
        }
        return true;
    }
}
?>

SOURCE: http://nik.chankov.net/2007/10/23/check-for-existing-childs-behaviour/

HTH.

I am new to CakePHP, so please take this answer with a grain of salt.

I believe since Venue has a relationship to Event you can access it without any modifications with something like:

$this->Event ...

from the Venue Model or Controller.

You should then me able to use a query to find any Event with that venue.

for use cakephp 3.5.1 try this..

in Products model

Products belongsTo Categories

in Categories controller

public function delete($id = null)
{
    $this->request->allowMethod(['post', 'delete']);
    if($this->checkassociated($id) > 0){
        $this->Flash->error(__('this category could not be deleted.'));
    }else{
        $category = $this->Categories->get($id);
        if ($this->Categories->delete($category)) {
            $this->Flash->success(__('this category has been deleted.'));
        } else {
            $this->Flash->error(__('this category could not be deleted.'));
        }
    }
    return $this->redirect(['action' => 'index']);
}

public function checkassociated($category_id){
    $itemsTable = TableRegistry::get('Products');
    $itemdata = $itemsTable->find('all')
        ->where(['Products.category_id'=>$category_id]);
    $number = $itemdata->count();
    return $number;
}