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In this module, we had the client be able to request and present information for a certain listing in the /listing/:id route of our application.

Server Project#

src/graphql/typeDefs.ts#

We created a single root-level listing field that can be queried from the client to receive the information for a certain listing. The listing query field queries for a listing in the "listings" collection of our database based on the id argument provided.

  type Query {

    authUrl: String!

    user(id: ID!): User!

    listing(id: ID!): Listing!

  }

The Listing object returned from the listing query field is to have certain information about a listing we want the client to access.

  type Listing {

    id: ID!

    title: String!

    description: String!

    image: String!

    host: User!

    type: ListingType!

    address: String!

    city: String!

    bookings(limit: Int!, page: Int!): Bookings

    bookingsIndex: String!

    price: Int!

    numOfGuests: Int!

  }

src/graphql/resolvers/Listing/index.ts#

In the listingResolvers map in the src/graphql/resolvers/Listing/index.ts file, we created the root-level query listing() resolver function to find a certain listing from the "listings" collection based on the id argument provided. If the viewer making the request is the user who owns the listing (i.e. is the host of the listing), we add an authorized property to the listing object to constitute that the viewer is authorized to see certain information about the listing.

export const listingResolvers: IResolvers = {  Query: {

    listing: async (

      _root: undefined,

      { id }: ListingArgs,

      { db, req }: { db: Database; req: Request }

    ): Promise<Listing> => {

      try {

        const listing = await db.listings.findOne({ _id: new ObjectId(id) });

        if (!listing) {

          throw new Error("listing can't be found");

        }

        const viewer = await authorize(db, req);

        if (viewer && viewer._id === listing.host) {

          listing.authorized = true;

        }

        return listing;

      } catch (error) {

        throw new Error(`Failed to query listing: ${error}`);

      }

    }

  },};

We've added a few other explicit resolver functions for the Listing GraphQL object.

• The id() resolver returns the string representation of the _id value of a listing document.

• The host() resolver attempts to returns a user object for the listing.host id value. listing.id represents the id of the user who owns the listing.

• The bookingsIndex() resolver returns a string representation of the listing.bookingsIndex map object.

• The bookings() resolver returns the list of bookings that have been made to the listing.