Creating a has_many relationship in Silverstripe

This guide will walk through how to create a basic has_many relationship between a page type and DataObject in Silverstripe. The page type we’ll create is a ProductsPage that will have many Products which are DataObjects.

Creating the ProductsPage page type

First let’s create the Products Page with the following code

<?php

namespace MySite\Pages;

use Page;

class ProductsPage extends Page {
    private static $table_name = 'ProductsPage';
}

Let’s also create a page controller for the ProductsPage

<?php

namespace MySite\Pages;

use PageController;

class ProductsPageController extends PageController {

}

After creating the ProductsPage, create a ProductsPage.ss template under the appropriate directory and rebuild your database and flush the cache by appending ‘dev/build?flush=all’ to end of your site URL.

Creating the Product DataObject

Now create a DataObject called Product like the one below.

<?php

namespace MySite\DataObjects;

use SilverStripe\Forms\TextField;
use SilverStripe\ORM\DataObject;

class Product extends DataObject {

    private static $table_name = "Product";

    private static $db = [
        'Name' => 'Text',
        'Price' => 'Varchar'
    ];

    public function getCMSFields()
    {
        $fields = parent::getCMSFields();

        $fields->addFieldsToTab('Root.Main', [
            TextField::create('Name'),
            TextField::create('Price')
        ]);
        
        return $fields;
    }

}

Creating the has_many and has_one relationship between the ProductsPage and Product DataObject

With our ProductsPage and Product DataObject created, we can now create the ‘has_many’ relationship between them.

In our ProductsPage let’s create the ‘has_many’ relationship that will link a ProductsPage to many Products.

<?php

namespace MySite\Pages;

use Page;

use MySite\DataObjects\Product;
use SilverStripe\Forms\GridField\GridField;
use SilverStripe\Forms\GridField\GridFieldConfig_RelationEditor;

class ProductsPage extends TopLevelPage
{
    // …
    
    private static $has_many = [
        'Products' => Product::class
    ];

    public function getCMSFields()
    {
        $fields = parent::getCMSFields();
        
        $fields->addFieldsToTab('Root.Products', [
            GridField::create(
                'Products',
                'Products',
                $this->Products(),
                GridFieldConfig_RelationEditor::create()
            )
        ]);

        return $fields;
    }
}

Notice we also added a GridField to manage the creating/updating of Products.

Now let’s also create a ‘has_one’ relation from the Product DataObject back to the ProductsPage. This ensures that a Product will only belong to one ProductsPage.

<?php

namespace MySite\DataObjects;

use MySite\Pages\ProductsPage;
use SilverStripe\Forms\TextField;
use SilverStripe\ORM\DataObject;

class Product extends DataObject {

    // …

    private static $has_one = [
        'ProductPage' => ProductsPage::class
    ];

}

After creating the ‘has_many’ and ‘has_one’ relations from the ProductsPage to the Product DataObject rebuild the database and flush the cache and you’re done.

If you want to see to a render each Product as its own page, go to the article Rendering DataObjects as pages using controller actions.