Content-type is not specified when returning c.text in bun

[watany-dev]

What version of Hono are you using?

4.0.7

What runtime/platform is your app running on?

Bun

What steps can reproduce the bug?

import { Hono } from 'hono'

const app = new Hono()

app.get('/', (c) => {
  return c.text('Hello Hono!')
})
app.get('/text', (c) => c.text('Text Response'))
app.get('/html', (c) => c.html('<p>HTML Response</p>'))
app.get('/json', (c) => c.json({ message: 'JSON Response' }))
app.get('/no-content-type', (c) => {
  return c.redirect('no content')
})

export default app

curl -I localhost:3000/json
HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Date: Wed, 28 Feb 2024 08:40:43 GMT
Content-Length: 0

curl -I localhost:3000/text
HTTP/1.1 200 OK
Date: Wed, 28 Feb 2024 08:41:05 GMT
Content-Length: 0

curl -I localhost:3000/html
HTTP/1.1 200 OK
Content-Type: text/html; charset=UTF-8
Date: Wed, 28 Feb 2024 08:41:09 GMT
Content-Length: 0

curl -I localhost:3000/no-content-type
HTTP/1.1 302 Found
Location: no content
Date: Wed, 28 Feb 2024 08:41:21 GMT
Content-Length: 0

What is the expected behavior?

I would like it to work as 'Content-Type', 'text/plain; charset=UTF-8'.

I am concerned if this should be addressed on the Adaptor side as it seems to be a problem on the Bun side.
oven-sh/bun#8530

What do you see instead?

No response

Additional information

I found this CI Bun from the failure.
#2247

In other words, this leads to the possibility that the specification "SSG to error on those without Content-type" may be difficult to implement due to the differences in Bun. There are three possible approaches

1. fix Bun Adaptor.
2. to fix SSG from hono/bun.
3. temporarily forgo the creation of a Content-type check function for SSG.

[watany-dev]

Note:

1. is not appropriate as it will affect performance.

[usualoma]

Sorry to bother you all - especially @watany-dev!
I was unaware that bun had such a specification.

4. Even in SSG, if there is no Content-Type, it is assumed to be text/plain.
   • In other words, the following code in the current main branch is the expected spec
     • https://github.com/honojs/hono/blob/main/src/helper/ssg/index.ts#L168

The "default is text/plain" seems a bit odd, but if hono itself has such a specification ( c.text() returns a response without Content-Type ), I think it makes sense to treat it as text/plan in SSG accordingly.

[yusukebe]

Hi @watany-dev @usualoma

As mentioned by @watany-dev, if we use c.text('foo') in a simple case, Hono does not add Content-Type:

app.get('/', (c) => c.text('foo'))

This is because the performance with and without Content-Type was significantly different when benchmarked in the past. Bun does not add Content-Type by default, but other runtimes add text/plain, so c.text() should be fine with the current specification.

When Hono didn't add Content-Type, it is expected to be text/plain, so I think @usualoma's "4" is a good choice.

[watany-dev]

@yusukebe @usualoma
Thank you. I also agree with option No. 4, that is, the current specifications are fine. The use of StatusCode should be discussed in a separate issue. Here's what I think should be done regarding the related tasks going forward. We will adapt as better methods are proposed.

• Close this ticket.

  • I have enough information, so it's okay to close it after the discussion ends. @yusukebe

• Close this PR fix(ssg): Error when ContentType is missing #2247.

  • Done.

• Submit a Pull Request for the specification "default Content-Type=text/plain" under Issue No. in the ticket -SSG: Should the default Content-Type be text/plain? #2244.

  • I will proceed with this afterward.