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In this module, we've created the capability for users to book listings in our application.

Server Project#

src/graphql/typeDefs.ts#

In the GraphQL API type definitions of our server project, we introduced a new root-level mutation field labeled createBooking.

  type Mutation {

    logIn(input: LogInInput): Viewer!

    logOut: Viewer!

    connectStripe(input: ConnectStripeInput!): Viewer!

    disconnectStripe: Viewer!

    hostListing(input: HostListingInput!): Listing!

    createBooking(input: CreateBookingInput!): Booking!

  }

The createBooking mutation accepts an input that is to have an object type of CreateBookingInput. The input is to contain a series of field values that describe the booking that is to be created, such as the id of the listing being booked, the payment source being made, and the check-in/check-out dates of the booking

  input CreateBookingInput {

    id: ID!

    source: String!

    checkIn: String!

    checkOut: String!

  }

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

We've constructed the resolver function for the createBooking mutation in the bookingResolvers map within the src/graphql/resolvers/Booking/index.ts file. The createBooking() resolver function does a few different things:

• The utility authorize() function is first called to verify the viewer making the request.

• The listing document being booked is found from the id argument passed in as input to the mutation.

• A check is made to verify the viewer making the booking is not the host of the listing.

• Another check is made to verify the check-out date is not before the check-in date of the booking.

• The bookingsIndex object of the listing is updated to recognize the new dates that have been booked for the listing.

• The total price of the booking is determined based on the number of days the listing is being booked.

• A check is made to verify the host is still connected with Stripe such that they will be able to receive payment.

• A Stripe charge is conducted to pay the host from the person creating the booking.

• The "bookings" collection is updated with a new booking document.

• The income of the user document of the host is updated with the new amount of income earned.

• The bookings field of the user document of the viewer is updated with the id of the new booking that has been made.

• The listing document of the listing being booked is updated to have a new bookingsIndex object. The bookings field of the listing document is also updated with the id of the new booking that has been made.

export const bookingResolvers: IResolvers = {  Mutation: {

    createBooking: async (

      _root: undefined,

      { input }: CreateBookingArgs,

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

    ): Promise<Booking> => {

      try {

        const { id, source, checkIn, checkOut } = input;

        let viewer = await authorize(db, req);

        if (!viewer) {

          throw new Error("viewer cannot be found");

        }

        const listing = await db.listings.findOne({

          _id: new ObjectId(id)

        });

        if (!listing) {

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

        }

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

          throw new Error("viewer can't book own listing");

        }

        const checkInDate = new Date(checkIn);

        const checkOutDate = new Date(checkOut);

        if (checkOutDate < checkInDate) {

          throw new Error("check out date can't be before check in date");

        }

        const bookingsIndex = resolveBookingsIndex(

          listing.bookingsIndex,

          checkIn,

          checkOut

        );

        const totalPrice =

          listing.price *

          ((checkOutDate.getTime() - checkInDate.getTime()) / 86400000 + 1);

        const host = await db.users.findOne({

          _id: listing.host

        });

        if (!host || !host.walletId) {

          throw new Error(

            "the host either can't be found or is not connected with Stripe"

          );

        }