...

/

Passing Data through our React Code

Passing Data through our React Code

Let's pass data through React in this lesson.

We'll cover the following...

The Row component

Following our change through, the VenueBody component doesn’t change much, it merely takes in the extra values and passes them along, giving each row its corresponding RowData:

Press + to interact
import * as React from "react"
import Row from "components/row"
import { VenueData } from "components/venue"
interface VenueBodyProps {
concertId: number
rowCount: number
seatsPerRow: number
ticketsToBuyCount: number
venueData: VenueData
}
const rowItems = ({
concertId,
rowCount,
seatsPerRow,
ticketsToBuyCount,
venueData,
}) => {
const rowNumbers = Array.from(Array(rowCount).keys())
return rowNumbers.map((rowNumber: number) => (
<Row
concertId={concertId}
key={rowNumber}
rowData={venueData[rowNumber]}
rowNumber={rowNumber}
seatsPerRow={seatsPerRow}
ticketsToBuyCount={ticketsToBuyCount}
/>
))
}
export const VenueBody = (props: VenueBodyProps): React.ReactElement => {
return (
<table className="table">
<tbody>{rowItems(props)}</tbody>
</table>
)
}
export default VenueBody

The Row component carries a lot of load here. It maintains a client-side status of each seat that is based on its ticket status and also the number of tickets the user is looking to buy, so as to prevent buying tickets so close to an already sold ticket that we can’t buy an entire block. It also has the click handler invoked when a user clicks on a seat.

Here’s the new version of the row:

Press + to interact
import * as React from "react"
import Rails from "@rails/ujs"
import Seat from "components/seat"
import { RowData, TicketData } from "components/venue"
interface RowProps {
concertId: number
rowData: RowData
rowNumber: number
seatsPerRow: number
ticketsToBuyCount: number
}
const Row = (props: RowProps): React.ReactElement => {
const [seatStatuses, setSeatStatuses] = React.useState(
Array.from(Array(props.seatsPerRow).keys()).map(() => "unsold")
)
React.useEffect(() => {
if (props.rowData) {
setSeatStatuses(
props.rowData.map((ticketData: TicketData) => ticketData.status)
)
}
}, [props.rowData])
function isSeatValid(seatNumber): boolean {
if (seatNumber + props.ticketsToBuyCount > props.seatsPerRow) {
return false
}
for (let i = 1; i < props.ticketsToBuyCount; i++) {
const seatStatus = seatStatuses[seatNumber + i]
if (seatStatus === "held" || seatStatus === "purchased") {
return false
}
}
return true
}
function validSeatStatus(seatNumber): string {
const seatStatus = seatStatuses[seatNumber]
if (seatStatus === "held" || seatStatus === "purchased") {
return seatStatus
} else {
return isSeatValid(seatNumber) ? "unsold" : "invalid"
}
}
function newState(oldStatus: string): string {
if (oldStatus === "unsold") {
return "held"
} else if (oldStatus === "held") {
return "unsold"
} else {
return "invalid"
}
}
function updateSeatStatus(seatNumber: number): string[] {
return seatStatuses.map((status: string, index: number) => {
if (
index >= seatNumber &&
index < seatNumber + props.ticketsToBuyCount
) {
return newState(seatStatuses[seatNumber])
} else {
return status
}
})
}
function onSeatChange(seatNumber: number): void {
const validStatus = validSeatStatus(seatNumber)
if (validStatus === "invalid" || validStatus === "purchased") {
return
}
const newSeatStatuses = updateSeatStatus(seatNumber)
setSeatStatuses(newSeatStatuses)
fetch(`/shopping_carts`, {
method: "POST",
headers: {
"X-CSRF-Token": Rails.csrfToken(),
"Content-Type": "application/json",
},
body: JSON.stringify({
concertId: props.concertId,
row: props.rowNumber + 1,
seatNumber: seatNumber + 1,
status: newSeatStatuses[seatNumber],
ticketsToBuyCount: props.ticketsToBuyCount,
}),
})
}
const seatItems = Array.from(Array(props.seatsPerRow).keys()).map(
(seatNumber: number) => {
return (
<Seat
clickHandler={onSeatChange}
key={seatNumber}
seatNumber={seatNumber}
status={validSeatStatus(seatNumber)}
/>
)
}
)
return <tr className="h-20">{seatItems}</tr>
}
export default Row

There are some small changes here because we are passing concertId and rowData into the props. ...