feat: add readFormData util

[Hebilicious]

Resolves #419

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This PR adds support for Request and FormData in event handler.

2 new helpers are introduced :

• getRequestFromEvent
• getFormData

This helpers relies on Request and FormData to be available in the global scope as per the Fetch specification, which means the tests are disabled for node < 18 (which is fine as 18 reaches EOL in 3 months)

// With a JSON body ...
const handler = eventHandler(async (event) => {
	const nativeRequest = await getRequestFromEvent(event);
	expect(nativeRequest instanceof Request).toBe(true);
	expect(nativeRequest.method).toBe("POST");
	expect(nativeRequest.headers.get("hello")).toBe("world");
	const body = await nativeRequest.json();
	expect(body).toMatchObject({
	  user: "john",
	});
	return "ok";
})

// With x-www-form-urlencoded data
const handler = eventHandler(async (event) => {
	const formData = await getFormData(event);
	const user = formData.get("user");
	expect(formData instanceof FormData).toBe(true);
	expect(user).toBe("john");
	return { user };
})

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[codecov]

Codecov Report

Merging #421 (c4581fd) into main (5c4521f) will increase coverage by 0.13%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #421      +/-   ##
==========================================
+ Coverage   78.23%   78.36%   +0.13%     
==========================================
  Files          26       26              
  Lines        2775     2792      +17     
  Branches      407      407              
==========================================
+ Hits         2171     2188      +17     
  Misses        604      604              

Impacted Files	Coverage Δ
src/utils/body.ts	95.13% <100.00%> (+0.49%)	⬆️

[pi0]

I think getRequestFromEvent is a nice addition but we might find a more straightforward solution to handle form data that does not require creating a whole Request object to parse form-data. (splitting into two PRs would be nice 🙏🏼 )

Update: Checking MDN docs, it seems we cannot directly construct FormData from body...

[Hebilicious]

@pi0 Updated the method names to readFormData and eventToRequest 👍🏽

[franklin-tina]

Hi @Hebilicious,
Lovely PR 😍
I was wondering if this will handle forms with multimedia data as well?

[Hebilicious]

@neo-franklin-tina Are you talking about multipart/form-data ? It should work by default yes.

[franklin-tina]

@neo-franklin-tina Are you talking about multipart/form-data ? You're right we should also support this.

Yes, something like that.
Thanks for the response

[pi0]

Rebased util with event.request from #454. Thanks for the ideas!