Generate object validators/transformers for Javascript languages

[schani]

We should have functions that just do validation of objects. We could make it an option whether to create validators, serializers/deserializers, or both.

[qm3ster]

Could use ajv-pack

[schani]

Sorry, this issue is incompletely worded. What's actually wanted here is simply functions that do the cast on a given JS object, instead of doing it on JSON.parse(jsonString), because sometimes you already have an object, and don't need to parse it.

So in addition to

export function toPokedex(json: string): Pokedex {
    return cast(JSON.parse(json), r("Pokedex"));
}

we would also generate

export function castPokedex(obj: any): Pokedex {
    return cast(obj, r("Pokedex"));
}

ajv-pack at this point is inadequate because

1. It doesn't support custom formats which we'll have sooner or later.

2. It doesn't support recursive references.

3. It can only validate, not transform the object. Right now we support renaming of properties to be convention-conformant, but data transformers will do more elaborate things (they already do in Python in C#, they're not implemented in JS yet)

[qm3ster]

Oh. I was actually looking for value validation, such as minimum and maximum on numbers that are for me currently ignored with quicktype schema->ts
Maybe you should add custom formats to ajv-pack
I see about the other stuff though.

[schani]

What's the reason you're not using ajv-pack right now?

minimum, maximum, and a few other constraints have recently been implemented in C++. The "proper" way to do this would be via transformers, but unfortunately transformers aren't implemented for JS yet, either. So the options would be either

1. implement transformers for JS, then add transformers for the assertions you need and implement those in JS.
2. just hack the constraints onto the current JS implementation.

2 is a lot easier than 1, but 1 is a lot more useful. In particular, it would allow us to easily add all current and future transformed string types to JS, and it would make it easy to implement the new assertions in target languages that already support transformers (C# and Python so far).

If you're interested in either, please let us know. We're always happy to help.

[qm3ster]

I am currently using json-schema-to-typescript to type the output of ajv-pack.
I'll probably end up automating the manual step between them for my particular case.
I do agree with 1. considering the scope of this project.
I was just not looking for that breadth of features (yet?)