Support for passing Standard Schema into `hono/validator`

[nakasyou]

What is the feature you are proposing?

Related: honojs/middleware#887

Standard Schema is a spec to make APIs of JavaScript validators unified. I'd like to propose adding Standard Schema support to hono/validator.

import { validator } from 'hono/validator'

import z from 'zod'
import * as v from 'valibot'
import { type } from 'arktype'

app.post('/zod', validator('json', z.number()), ...)
app.post('/valibot', validator('json', v.number()), ...)
app.post('/arktype', validator('json', type('number')), ...)

Currently, we can use this with @hono/standard-validator as a 3rd party middleware, but using it needs to install another package. It can be a little troublesome.

Some frameworks are using Standard Schema natively¹ and they are increasing (Astro 6.0 may support Standard Schema²). I think this will be a moderate incentive to use the frameworks supporting Standard Schema.

Pros

• We will be able to use our favorite validators without installing other dependencies.
• The amount of code to implement it is very short so we don't need to worry about bundled size.

Cons

• Currently hono/validator provides very simple APIs and uses minimal algorithm. This can be broken with implementing this.
• Standard Schema is not a Web Standard.

Footnotes

1. https://standardschema.dev/#:~:text=What%20tools%20/%20frameworks%20accept%20spec%2Dcompliant%20schemas%3F ↩

2. https://github.com/standard-schema/standard-schema/issues/21#issuecomment-2931018088 ↩

[EdamAme-x]

I believe that hono/validator should be the most abstracted middleware, I have some reservations about this.
Users who want to use a standard schema are probably already using something like @hono/zod-validator, so I don't think it's that much of a hassle.

Of course, I understand that there are users who would find this change convenient.

[yusukebe]

Hi @nakasyou @EdamAme-x

Thank you for the suggestion and the comment!

Interesting. As @EdamAme-x mentioned, the current hono/validator is with minimal implementation, and it's great (it's one of my favorite APIs in honojs/hono). I think it will be good to create hono/standard-validator middleware in the core, with moving the @hono/standard-validator to here:

import { standardValidator } from 'hono/standard-validator

But, we already have @hono/standard-validator, so we may need to move it. I think both are okay.

[nakasyou]

@yusukebe moving standardValidator into this repo looks good to me. @muningis what do you think?

[yusukebe]

Related to honojs/middleware#1241