feat(request): return new Request with cached body in raw getter

[yusukebe]

This PR will fix the problem that we wanted to resolve with #4382.

Problem

The following code will cause the error:

import { Hono } from 'hono'

const app = new Hono()

app.post('/', async (c) => {
  const data = await c.req.json()
  await c.req.raw.json() // Body already used!
  return c.json(data)
})

export default app

This is because when you do c.req.raw, the body to be used is already consumed. This is explained in #4382 (comment).

Solution

In this PR, it will create a new Request object with a cached body when c.req.raw is called. The reason why it does not use getter/setter and uses Object.defineProperty is that if it were to use getter/setter, it would fail with the spread syntax {...c.req}.

Caveat

The code size will be increased.

The performance may degrade, but it's small.

The author should do the following, if applicable

• Add tests
• Run tests
• bun run format:fix && bun run lint:fix to format the code
• Add TSDoc/JSDoc to document the code

[github-actions]

Bundle size check

	main (393ded9)	#4425 (eacb440)	+/-
Bundle Size (B)	18,294B	18,557B	263B
Bundle Size (KB)	17.87K	18.12K	0.25K

Compiler Diagnostics (tsc)

	main (393ded9)	#4425 (eacb440)	+/-
Files	300	300	0
Lines	140,207	140,228	21
Identifiers	127,056	127,083	27
Symbols	264,250	264,292	42
Types	155,889	155,935	46
Instantiations	538,872	538,826	-46
Memory used	310,269K	308,090K	-2,179K
I/O read	0.02s	0.03s	0.01s
I/O write	0s	0s	0s
Parse time	0.72s	0.78s	0.06s
Bind time	0.3s	0.3s	0s
Check time	2.67s	2.77s	0.1s
Emit time	0s	0s	0s
Total time	3.69s	3.86s	0.17s

Compiler Diagnostics (typescript-go)

	main (393ded9)	#4425 (eacb440)	+/-
Files	269	269	0
Lines	118,096	118,117	21
Identifiers	116,489	116,516	27
Symbols	353,957	353,972	15
Types	277,831	277,878	47
Instantiations	3,528,587	3,528,359	-228
Memory used	223,102K	223,175K	73K
Memory allocs	10,491,846	10,491,870	24
Parse time	0.07s	0.078s	0.008s
Bind time	0.024s	0.016s	-0.008s
Check time	1.426s	1.509s	0.083s
Emit time	0s	0s	0s
Total time	1.534s	1.605s	0.071s

---

Reported by octocov

[github-actions]

HTTP Performance Benchmark

Framework	Runtime	Average	Ping	Query	Body
hono (origin/main)	bun	38,250.69	53,142.55	33,106.71	28,502.80
hono (current)	bun	37,401.78	52,662.68	31,646.26	27,896.40
Change		-2.22%	-0.90%	-4.41%	-2.13%

[codecov]

Codecov Report

❌ Patch coverage is 94.28571% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.28%. Comparing base (393ded9) to head (4c411e6).

Files with missing lines	Patch %	Lines
src/request.ts	94.28%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4425      +/-   ##
==========================================
+ Coverage   91.25%   91.28%   +0.02%     
==========================================
  Files         171      171              
  Lines       10913    10933      +20     
  Branches     3144     3149       +5     
==========================================
+ Hits         9959     9980      +21     
+ Misses        953      952       -1     
  Partials        1        1              

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[kamaal111]

In HonoRequest, where we don't need to access the raw body, can we use the private _raw instead?

This might improve the performance slightly

[kamaal111]

Can you also verify that it still works as expected when try to get the body for the third time?

To switch it up a bit we can also use .text which would still result in getting the cached body and constructing a new Request object