7. Exercise 3: Listing activities
5m

Exercise 3: A listing's activities (⏳ 5 min)

Uncomment the following lines from the listings.graphql schema:

listings.graphql
type Listing {
  # ...other Listing fields
  # EXERCISE: LISTING ACTIVITIES
  "The activities available for this listing"
  activities: [Activity!]!
}


# EXERCISE: LISTING ACTIVITIES
type Activity {
  id: ID!
  name: String!
  description: String
  terrain: String
  groupSize: Int
}
Task!

Save your changes. rover dev will now give you an error:

error[E029]: Encountered 6 build errors while trying to build a supergraph.


Caused by:
  CONNECTORS_UNRESOLVED_FIELD: [listings] No connector resolves field `Listing.activities`. It must have a `@connect` directive or appear in `@connect(selection:)`.
  CONNECTORS_UNRESOLVED_FIELD: [listings] No connector resolves field `Activity.id`. It must have a `@connect` directive or appear in `@connect(selection:)`.
  CONNECTORS_UNRESOLVED_FIELD: [listings] No connector resolves field `Activity.name`. It must have a `@connect` directive or appear in `@connect(selection:)`.
  CONNECTORS_UNRESOLVED_FIELD: [listings] No connector resolves field `Activity.description`. It must have a `@connect` directive or appear in `@connect(selection:)`.
  CONNECTORS_UNRESOLVED_FIELD: [listings] No connector resolves field `Activity.terrain`. It must have a `@connect` directive or appear in `@connect(selection:)`.
  CONNECTORS_UNRESOLVED_FIELD: [listings] No connector resolves field `Activity.groupSize`. It must have a `@connect` directive or appear in `@connect(selection:)`.

Exercise #3 Goal

🎯 Retrieve data for the Listing.activities .

Use this REST API endpoint:

https://activities-rest-api-0d717e1922e0.herokuapp.com/location/:id/activities

After successfully completing the exercise, you should get data back when running the GetListingActivities below:

GetListingActivities
query GetListingActivities($listingId: ID!) {
  listing(id: $listingId) {
    id
    title
    activities {
      id
      name
      description
      terrain
      groupSize
    }
  }
}

For the Variables section:

{
  "listingId": "listing-1"
}

Recap: $this

Check your work

Answer the following questions after you've completed the exercise. Lost? Check out the hints and solution below.

For the listing with id listing-1, which of the following statements about the listing's activities are true?
How many network calls did the GetListingActivities operation make?

💭 Hints

✅ Solution

listings.graphql
extend schema
  # ...other schema extensions
  @source(
    name: "activities"
    http: { baseURL: "https://activities-rest-api-0d717e1922e0.herokuapp.com" }
  )


type Listing {
  # ...other Listing fields
  "The activities available for this listing"
  activities: [Activity!]!
    @connect(
      source: "activities"
      http: { GET: "/location/{$this.id}/activities" }
      selection: """
      id
      name
      description
      terrain
      groupSize
      """
    )
}


# EXERCISE: LISTING ACTIVITIES
type Activity {
  id: ID!
  name: String!
  description: String
  terrain: String
  groupSize: Int
}
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