There's support for validating promise types, but I don't see a way to create async validators.

What I'm thinking of is something like this:

const foreignKey = z.string().refine(idExistsAsync, {
  message: "ID not found",
});
foreignKey.parseAsync("1234")

Where idExistsAsync is some function that asynchronously checks some backen

default

const V = require('fastest-validator');

const v = new V();

const schema = {
  tuple: {
    type: 'tuple',
    empty: false,
    items: [{ type: 'string', default: '1' }],
  },
};

const data = { tuple: [] };
console.log(v.validate(data, schema));
console.log(data);

[
  {
    type: 'tupleEmpty',
    message: "The 'tuple' field must not be an empty

In our codebase I observed that the generated files are often recompiled without explicitly cleaning them or changing the schema. This isn't a big deal for small schemas but in our case it's over 400 files that are being recompiled and takes several seconds.

I don't have a repro-case yet but it should be fairly straight forward. I can imagine using one of the test/example projects and checking