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How to create set up a many_many relation using the SS3 gridfield
In this article we’re going to a create a very simple shop. We’ll create pages for various product categories. And we’ll create products. Some our products will appear in more than one category.
Eg. Each ‘Category’ -> has many-> Products
and each ‘Porduct’ -> has many -> ‘Categories’
This is many_many relationship. In the database, we end with 3 tables – one containing the Categories, one containing the Products, and one table which contains a list of ‘links’ between the products and categories.
Create the Category Page
Create ProductCategoryPage.php
This is the page on your site that will list the the products.
We define the many_many relation to the product, and then set up the gridfield to allow us to manage the products in the CMS.
We use the config option ‘GridFieldConfig_RelationEditor’ to make the datagrid show the right options. We also add “GridFieldDeleteAction(‘unlinkrelation’)” to the config. This allows us to ‘delete’ a product altogether (from all categories), or just remove (unlink) it from the category page we’re editing.
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<?php class ProductCategoryPage extends Page { public static $many_many = array( 'Products' => 'Product' ); public function getCMSFields() { $fields = parent::getCMSFields(); $gridFieldConfig = GridFieldConfig_RelationEditor::create()->addComponents( new GridFieldDeleteAction('unlinkrelation') ); $gridfield = new GridField("Products", "Product", $this->Products(), $gridFieldConfig); $fields->addFieldToTab('Root.Products', $gridfield); return $fields; } } class ProductCategoryPage_Controller extends Page_Controller { public static $allowed_actions = array ( ); public function init() { parent::init(); } } |
Create the Product Object
Create Product.php
This is the object that contains data about each product – at this stage we simply have a title and a photograph.
We also define the fact that this item belongs to a many_many – this ties the two parts together nicely.
We’ll also define the summary fields shown in the CMS – or else it will just show the ID, which isn’t much use.
We’re adding a function here to show a thumbnail image – why not – it looks nice!
And finally, we’re calling getCMSFields, and setting up a datagrid so that when we’re on a product page, we get a nice table showing us what categories are related to that product.
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<?php class Product extends DataObject { public static $db = array( 'Title' => 'Varchar' ); // One-to-one relationship with profile picture and contact list page public static $has_one = array( 'Image' => 'Image' ); public static $belongs_many_many = array( 'ProductCategoryPage' => 'ProductCategoryPage' ); // Summary fields public static $summary_fields = array( 'ID' => 'ID', 'Thumbnail' => 'Thumbnail', 'Title' => 'Title' ); public function getThumbnail() { return $this->Image()->CMSThumbnail(); } public function getCMSFields() { $fields = parent::getCMSFields(); $gridFieldConfig = GridFieldConfig_RelationEditor::create()->addComponents( new GridFieldDeleteAction('unlinkrelation') ); $gridFieldConfig->removeComponentsByType('GridFieldAddNewButton'); $gridfield = new GridField("ProductCategoryPage", "ProductCategoryPage", $this->ProductCategoryPage(), $gridFieldConfig); $fields->addFieldToTab('Root.ProductCategoryPage', $gridfield); return $fields; } } |
At this stage, upload the files, run a dev/build and create a few ‘ProductCategoryPages’ in your CMS.
Adding New Products
In your CMS, choose one of the new ‘Product Category’ Pages. And move to the ‘Products’ tab.
You should see a screen similar to the image above
Click ‘add product’
Give the new product a title, in this case we’ll call it ‘Wheel’ – but don’t bother adding an image. You’ll need to click ‘Create’ first, and then add the image, then ‘Save’ it again.
Once you’ve saved your product, click ‘Back’ at the top of the page to return to the main category page
Adding an existing product to another category
Now that we have a product, we can add this product to another category by going to the other page, and again, to the ‘products’ tab
Here is another list of products – this time though, instead of clicking ‘Add Product’ to create a new products, we’ll search for an existing product – in this case ‘wheel’.
Enter the first few letters of the product in the box next to ‘add product’ and Silverstripe will come with a list of items that match the search. Click on the item you want to add, and then click ‘Link Existing’. The item will now appear in both category pages.
Removing an Item
At the start of this article we added
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new GridFieldDeleteAction('unlinkrelation') |
It’s now that this little line becomes important. It adds an extra icon into right column
These icons are ‘Edit’, ‘Delete’, and ‘Unlink’
‘Delete’ will remove the product from the database – and remove it from any categories it belong to.
The ‘Unlink’ button allows you to remove it from just this page while leaving it in the database for any other pages that it might belong to.
Note. If you click on an item, and then click on the ‘product category’ tab in the top right – you’ll see a list of pages this item belongs to, where you can also unlink a category from the product, or attach a new category. However note that if you click the ‘delete’ button here you will be deleting a page off your site.
Creating the Templates
Now come the fun bit – making the template to display the information.
The details will of course depend how you want your page to look. This is very basic example
Create ProductCategoryPage.ss with your templates Layout folder
Something like the following will be enough to show your products…
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<% loop Products %> <h3>$Title</h3> $Image.SetWidth(100) <% end_loop %> |