Question

i’ve got a problem with a foreign key field : i created a categories table with MySQLWorkbench, which is linked by a 1:n relation to another table : Articles. It seems to work, because in Articles, there is a categories_id “INT” field .

I baked the whole project, everything works fine, except this foreign key : instead of an input that would receive the “number” i would write to specify the categories_id number, there is a kind of empty “select” (list) that contains nothing, so i cannot enter any number for the categories_id field in my database :

here’s the image :

If i try to “force” and add an “article” (so without the category), there is this error :

Error: SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (ecommerce.articles, CONSTRAINT fk_articles_categories FOREIGN KEY (categories_id) REFERENCES categories (id) ON DELETE NO ACTION ON UPDATE NO ACTION)

And here’s my add.ctp file (it is written input for the categories_id, so i don’t know what to change) :

<div class="articles form">
<?php echo $this->Form->create('Article');?>
    <fieldset>
        <legend><?php echo __('Add Article'); ?></legend>
    <?php
        echo $this->Form->input('nom');
        echo $this->Form->input('prix');
        echo $this->Form->input('categories_id');
    ?>

Thanks for your help

---

EDIT:

here’s what i added :

class Article extends AppModel {

    var $belongsTo = array(
        'Category' => array(
            'className'    => 'Category',
            'foreignKey'    => 'category_id'
         )
    );
}

and :

class Category extends AppModel {

    var $hasMany = array(
        'Article' => array(
            'className'    => 'Article',
            'foreignKey'    => 'category_id'
         )
    );
}

and in the controller (add()) :

public function add() {
        //$this->set('categories',$this->Article->Category->find('all'));
        //$c = $this->Article->Category->find('all', array("recursive"=>-1, 'fields'=>array('id', 'nom')));
        $c = $this->Article->Category->find('list');
        $this->set('cat', $c);

but in my view, pr($cat) returns an empty Array…

<?php
    echo $this->Form->input('nom');
    echo $this->Form->input('prix');
    echo $this->Form->input('category_id', array('option'=>$cat));
            pr($cat);
?>

Answer 1

It’s because of the naming convention.. if your table is called categories then the foreign key in articles should be category_id (singular) and the model must be called Category. The controller should pass to the view a variable called ‘$categories’ (plurar)

$this->set('categories',$this->Article->Category->find('list'))

and the input in the view has to be:

echo $this->Form->input('category_id');

don’t forget to change the foreign key in the model too

Hope this helps 🙂