In this lesson, you will add reference fields to the Product and Landing page models to connect them to other models in the schema. The reference type, direction, and cardinality configured here determine exactly what you will query later in the API Playground.

#Products and categories

Products need to be assignable to multiple categories, and categories need to display all their products. This requires a many-to-many, two-way reference. A two-way reference is required so you can query in both directions: from a product to its categories, and from a category to all its products.

1. Open the Product model in the Schema editor and from the right sidebar, add a Reference field.

2. Configure the reference field with the following information:

   Define relationship

   Field	Input
   Reference type	Allow only one model to be referenced
   Model to reference	ProductCategory
   Reference directions	Two-way reference
   Allow multiple Products per ProductCategory	Select checkbox
   Allow multiple ProductCategories per Product	Select checkbox
   Relationship cardinality	The graphic displays that the relationship is of type many-to-many

   Configure reference

   Field	Input
   Display name	Pre-configured. Leave as is.
   API ID	Pre-configured. Leave as is.
   Description	Select the categories that apply to your product
   Field visibility	Read / Write

   Configure reverse field

   Field	Input
   Display name	Pre-configured. Leave as is.
   API ID	Pre-configured. Leave as is.
   Field visibility	Read / Write

3. Click Add to save.

The reference field appears at the bottom of the model. Use the six-dot handle to drag it above the slug field.

What this enables: In lesson 7, you will be able to query productCategory(where: { slug: "sportswear" }) { products { productName } }. The query returns all products within that category. This is possible because of the two-way direction configured here.

#Landing page references

The Landing page model needs to display featured blog posts, product categories, and seller information. Each of these is a one-way reference. The Landing page queries into those models, but those models do not need to query back into Landing pages.

1. Open the Landing page model in the Schema editor and from the right sidebar under Relation, select Reference.

2. Configure the reference field for the Blog post model with the following information:

   Define relationship

   Field	Input
   Reference type	Allow only one model to be referenced
   Model to reference	BlogPost
   Reference directions	One-way reference
   Allow multiple BlogPosts per LandingPage	Select checkbox

   Configure reference

   Field	Input
   Display name	Pre-configured. Leave as is.
   API ID	Pre-configured. Leave as is.
   Description	Featured item
   Field visibility	Read / Write

3. Click Add to save.

4. Add another Reference field from the right sidebar. Configure the reference field for the Product category model with the following information:

   Define relationship

   Field	Input
   Reference type	Allow only one model to be referenced
   Model to reference	ProductCategory
   Reference directions	One-way reference
   Allow multiple ProductCategories per LandingPage	Select checkbox

   Configure reference

   Field	Input
   Display name	Pre-configured. Leave as is.
   API ID	Pre-configured. Leave as is.
   Description	Browse our categories
   Field visibility	Read / Write

5. Click Add to save.

6. Add another Reference field from the right sidebar. Configure the reference field for the Seller information model with the following information:

   Define relationship

   Field	Input
   Reference type	Allow only one model to be referenced
   Model to reference	SellerInformation
   Reference directions	One-way reference
   Relation cardinality	To one

   Configure reference

   Field	Input
   Display name	Pre-configured. Leave as is.
   API ID	Pre-configured. Leave as is.
   Description	Business information
   Field visibility	Read / Write

7. Click Add to save.

Your Landing page model should now look like this:

Your Landing page model so far

Why one-way for Landing page references, but two-way for Products and categories? A Blog post, Product category, or Seller information entry has no use case for querying which landing pages reference it. The two-way reference on Products and categories exists because the project needs to navigate from both sides. Where that bidirectional query isn't needed, a one-way reference keeps the schema clean.

#What's next

Lesson 3 - Enumerations

Or, go to the Tutorial overview for the full lesson list.