4. Building the schema
2m

Overview

Time to put what we learned about to work.

In this lesson, we will:

  • Define our schema

Building the schema

Let's navigate to the src directory. In there, we're going to create a new file called schema.graphql.

📂 src
 ┣ 📄 graphql.d.ts
 ┣ 📄 helpers.ts
 ┣ 📄 index.ts
 ┗ 📄 schema.graphql

✏️ Let's define that schema

Referring back to our featured listings mockup, we identified that we need some data for each listing.

A screenshot of Airlock, focused on the row of featured listings and their required fields

For this course, we're going to skip the listing photo and overall rating, and tackle a slightly pared-down version of the mockup.

Here are the basic we'll start with:

  • title
  • numOfBeds
  • costPerNight
  • closedForBookings

We'll also need a that we can use to differentiate one listing from another—we'll give this field the name id.

With our set of in mind, let's bring the Listing type to life!

The Listing type

Let's define the Listing type in our schema.graphql file and add a description right away.

schema.graphql
"A particular intergalactic location available for booking"
type Listing {
  # Fields go here
}

Now for the listing's , we'll have:

  • id of type ID!
  • title of type String!
  • numOfBeds of type Int
  • costPerNight of type Float
  • closedForBookings of type Boolean

So we should end up with a Listing type that looks like this:

Be sure to note the nullability of each of your Listing type's !

schema.graphql
"A particular intergalactic location available for booking"
type Listing {
  id: ID!
  "The listing's title"
  title: String!
  "The number of beds available"
  numOfBeds: Int
  "The cost per night"
  costPerNight: Float
  "Indicates whether listing is closed for bookings (on hiatus)"
  closedForBookings: Boolean
}

Not seeing the nice syntax highlighting you want? Check out the GraphQL: Syntax Highlighting extension for VS Code.

The Listing type is complete for now, but we need a way to actually ask our for listing data. For that, we have a separate Query type.

The Query type

The Query type is defined like any other :

schema.graphql
type Query {
  # Fields go here
}

The of this type are entry points into the rest of our schema. These are the top-level that our client can for. For now, we're only interested in fetching the list of featured listings for our homepage.

Let's name the featuredListings to make it as descriptive as possible. We want this to return a non-nullable list of non-nullable Listing types ([Listing!]!). on the Query type can return null, but in this case, we know our data source will return data for the listings. Don't forget to add a description for the !

schema.graphql
type Query {
  "A curated array of listings to feature on the homepage"
  featuredListings: [Listing!]!
}

Our schema is now fully defined to support our first feature!

Practice

Which of these statements about the Query type are true?
Code Challenge!

Define a Query type with a field, popularPlanets, that returns a non-null List of non-null Planet types. Remember to give your field a description!

Loading progress

Key takeaways

  • We use the Query type to define the top-level a client can for. These fields are the entry points into our schema.

Up next

This course is all about building a , so let's get into it! It's time to meet .

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