arktype•3mo ago

File type

I noticed you can do types like File, I was wondering if it's possible to do things like validate file size?

30 Replies

ssalbdivad•3mo ago

You can use .narrow for that to add custom validation logic

zxOP•3mo ago

when using narrow, how do you set an error message?

ssalbdivad•3mo ago

https://arktype.io/intro/adding-constraints/#narrow

ArkType

Adding Constraints

TypeScript's 1:1 validator, optimized from editor to runtime

zxOP•3mo ago

Thanks!

ssalbdivad•3mo ago

No problem. I've seen that question before. I would actually consider supporting a builtin < operator for File as well, not sure what the default units would be though. Bytes I guess since that's what it is in Node?

zxOP•3mo ago

Yeah I was thinking bytes would be fine

ssalbdivad•3mo ago

Would be kinda awkward though to have a long value since comma separators aren't supported yet. Guess we could allow stuff like File < 1M

zxOP•3mo ago

For now, narrow seems fine, but I was wondering if there's more documentation regarding custom error messages or test examples?

ssalbdivad•3mo ago

That's an area where the docs really need to be fleshed out. There are a lot of options though. You can kinda see what you can configure when you do ctx. and see what is suggested. ctx.reject allows you to add an error and return false like mustBe but you can pass an object with a bunch of config options

zxOP•3mo ago

.reject works perfectly, thanks a lot!

ssalbdivad•3mo ago

The error customization API is super rich so it should be a big advantage but since it's not fully documented yet it's actually the opposite for most users. I promise I will address that ASAP 🙏

zxOP•3mo ago

Sounds good! I really like ArkType compared to my experience with other validators so far but it's been hard figuring out things like this.

ssalbdivad•3mo ago

Yeah definitely understand that. I hope that once you do figure something out, it's kind of generalizable- things are composable and there are very few edge cases. But I totally realize that getting started is the biggest hurdle now and want to address that by ensuring the most important parts of the API have a decent reference

PIat•3mo ago

I would definitely be using a utility function (similar to ms: https://www.npmjs.com/package/ms) to convert MB to bytes and using as const

type({
    myFile: `File<${convertToBytes('30mb') as const}`
})

type({
    myFile: `File<${convertToBytes('30mb') as const}`
})

Adding MB and/or KB would be a lot smoother DX

ssalbdivad•3mo ago

I don't think you need as const, wouldn't be narrowed anyways I assume Also you probably don't need a dep for dividing by a constant right? 😛

PIat•3mo ago

Actually now that I'm thinking about it, only Arktype knows what the return value from the string would be 😁 ms only returns string or number

ssalbdivad•3mo ago

AT lets you interpolate non-narrowed numbers for ranges/divisors Why would it be a string?

PIat•3mo ago

When you insert 1000 it will convert to 1s If 1s it'll convert to 1000

ssalbdivad•3mo ago

Hmm I guess it depends on how many conversions you need, but if you just want MB you could probably just implement it in a couple lines

PIat•3mo ago

I really like having numbers be written in natural language. Had my share of 5 * 60 * 1000

ssalbdivad•3mo ago

A well named function makes sense, i'd just expect most people would want to specify constraints with a single unit (maybe MB) so I'd probably just implement a function to do that

PIat•3mo ago

Would look great, but it's not critical right now. It'd just be sugar. When handling uploads, you'd also check the MIME type and probably the actual contents, so at that point you'd create a narrow anyways

ssalbdivad•3mo ago

Yeah definitely not prioritizing now haha. Would conisider creating an issue since it's the kind of thing that can be good for external contributors

PIat•3mo ago

Should I file it?

ssalbdivad•3mo ago

Sure, would be happy to have it in the backlog @PIat thanks!

PIat•3mo ago

Thank you too 😊

TizzySaurus•3mo ago

Would you have that distingiuish between Mb and Mib etc.? Where Mb = 1000^2 bytes and Mib = 1024^2 bytes.

Dimava•3mo ago

mb = 1000^2 bits (╯°□°)╯︵ ┻━┻ But yes that's an interesting question I'd say it should be Bytes only, base1024 If you need 10-powered just use 123e3

// example:
const discordAttachment = type('File < 5M')
const driveSizeInFakeGigabytes = type('File < 100e9')

// example:
const discordAttachment = type('File < 5M')
const driveSizeInFakeGigabytes = type('File < 100e9')

ssalbdivad•3mo ago

Yeah there'd have to be a suffix but I'd probably just pick one or the other not both haha

PIat•3mo ago

It would be the technically correct way Pretty readable too..?

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File type