URL Query Parameters

URL query parameters are key-value pairs that appear after the ? symbol in a URL. They provide a way to pass additional data to your application endpoints.

Basic Usage

Here's how to access query parameters in your Fastro application:

import fastro, { HttpRequest } from "https://fastro.deno.dev/mod.ts";

const f = new fastro();

f.get("/:user", (req: HttpRequest) => {
  const data = {
    user: req.params?.user,
    title: req.query?.title,
  };
  return Response.json(data);
});

await f.serve();

How It Works

1. Route Parameter: The :user in the route captures the path segment
2. Query Access: Use req.query to access query parameters
3. Safe Access: The ?. operator provides safe property access

Example Request

Access your endpoint with query parameters:

http://localhost:8000/agus?title=head

This will return:

{
  "user": "agus",
  "title": "head"
}

Multiple Query Parameters

You can handle multiple query parameters:

f.get("/:user", (req: HttpRequest) => {
  const data = {
    user: req.params?.user,
    title: req.query?.title,
    category: req.query?.category,
    limit: req.query?.limit,
  };
  return Response.json(data);
});

Example request:

http://localhost:8000/john?title=article&category=tech&limit=10

Query Parameter Validation

For production applications, consider validating query parameters:

f.get("/:user", (req: HttpRequest) => {
  const title = req.query?.title;
  const limit = parseInt(req.query?.limit || "10");

  if (!title) {
    return new Response("Title parameter is required", { status: 400 });
  }

  const data = {
    user: req.params?.user,
    title,
    limit: Math.min(limit, 100), // Cap at 100
  };

  return Response.json(data);
});

Best Practices

• Always use optional chaining (?.) when accessing query parameters
• Validate and sanitize query parameter values
• Provide default values for optional parameters
• Consider the maximum URL length limitations
• Use meaningful parameter names

Next Steps

Learn about Application Middleware to add common functionality across your routes.