verify Table ID type in a form with zod

[solemn swift]

I want to submit an id of convex type Id<"part"> with a form. I'm doing form validation with zod and wondering what is the best way to do this. If i use z.string() for the part ID, typescript complains that string can not be assigned to Id<"part"> when calling the mutation function. This sounds reasonable, as the mutation indeed expects an argument of type Id<"part">.

I get correct types and no typescript error when using z.custom<Id<"part">>() to validate the field. But I think I still need to add a validator function to this custom type, because zod says If you don't provide a validation function, Zod will allow any value. I can add a manual check to make sure the provided value is indeed a string, and maybe check length and whatnot. But I'm wondering if I'm missing something here... Is there a best practice for a scenario like this?

[tough rock]

Here's an example of a zod validator that validates that the value is a string, and casts it to Id<"myTable"> https://github.com/get-convex/convex-helpers/blob/a6b19af85bb4c4ed5ef11b2519ef51ef4bd41f3c/convex/lib/withZod.ts#L18

Currently, it's not possible to check if a string is an ID from a specific table outside of a Convex function (v.id("myTable") in an arg validator or checking db.normalizeId("myTable", myId) is not null), so the best you can do for validating input on the client is to check that the value is a string (we've thought about adding a function to validate that something matches our ID format, or one day adding the ability to validate that a string is an ID from a particular table from client code).

Does this help?

[solemn swift]

Yeah, sounds good! Thank you 🙂