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Comment by avmich | Hacker News Reader

Wonder in which language class members can have such JSON Schema requirements as "an integer which is a multiple of integer X" or "string which matches regexp R". Also not sure which other schema system is better than JSON Schema across many different features.

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They're saying that the tool doesn't fit their priorities for their use case. I suspect you might be trying to say that their use case isn't what the tool is designed for, but you've phrased it in a way that comes across as condescending for not knowing what the tool even does. I'm not sure if you're trying to convince them that the tool would in fact be superior for their use case or if you're unhappy with them for giving this feedback in a context that you think isn't appropriate, but in either case I think it would be more effective to just state your point directly instead of passive-aggressively.

Ok, direct statement. I've tried some alternatives to JSON Schema, e.g. Protobuf. Left with some disappointment towards those alternatives. JSON Schema so far looks pretty good to me in comparison - overall, not for some specific cases, which are frankly rare.

> Wonder in which language class members can have such JSON Schema requirements as "an integer which is a multiple of integer X" or "string which matches regexp R".

Any language with a half-decent type system can represent that at the type level. And certainly any language worth knowing can trivially check whether an integer is a multiple of integer X or a string matches regexp R, which is what grandparent was getting at.

We seem to talk about different things. When doing deserialization, many wouldn't expect to add a custom code which would translate data and validate it - otherwise we would write the whole deserialization ourselves, I guess.

Most validation has to be done in custom code after deserialization (e.g. maybe a schema can enforce that the "collection ID" is in the right format, but it can't enforce that that collection actually exists in the datastore). There's definitely value in having a library/code generator/etc. to mechanically do the bytes -> structured value deserialization, but the cost/benefit of doing more complex validations at that stage is very questionable IME.

For simple enough APIs it's possible to have all the validation in the form of JSON Scheme. Surely the id may be missing, but that could be not a "client error" - the input is syntactically valid, and for some APIs that's enough - but will cause the server to return the empty result set.

You can't accept a write if you're going to break a foreign key constraint when you insert the row. And I struggle to imagine a case where you want to do complex validation like "multiple of x" or "matches this regex" but don't want to actually check if the thing exists.

I used matching regexes to check if a particular string actually has a time moment, in the form YYYY-MM-DD hh:mm:ss.xxx .

If you add events, they may not have FKs, you just add them to the table while generating PKs on the fly. This is useful in many cases. There could be other approaches with different cases, I suspect.

This will be possible in my programming language https://letlang.dev It's going all in on dynamic typing.

NB: It's actually already possible, since the type system is already implemented, it's just that many features of the language are not yet available.

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