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How a web request reaches the database

2 of 8

The trip · Lesson 3 of 8

One request, slowed down

Follow GET /orders/42 from the browser to Postgres and back.

7 min

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From “How a web request reaches the database”

One request, slowed down

export async function getOrder(req: Request) {
A function the router calls for every request to /orders/:id.
const id = Number(req.url.split("/").at(-1));
Take the last part of the path, "42", and turn it into a number.
const order = await db.query("select * from orders where id = $1", [id]);
Borrow a pooled connection and send one SQL query. $1 keeps the id out of the SQL text.
if (!order) return new Response(null, { status: 404 });
No row came back: tell the browser the order does not exist.
return Response.json(order);
Turn the row into JSON and send it as the response body.
}

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Why does the server keep a pool of database connections?

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How a web request reaches the database
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What does DNS do for a request?

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