Is there any alternative ajv(json-schema validator) for deno?

Question

I'm looking for a ajv-like json schema validator for deno. Wondering is there any alternative?

Abiosis

Here's the most relevant Github Issue: github.com/ajv-validator/ajv/issues/1850 – Instantly

Answer 1

You have some options to use none-deno modules.

The easiest way is to use a service like esm.sh and import it like:

import Ajv from 'https://esm.sh/[email protected]';
import addFormats from 'https://esm.sh/[email protected]';
const ajv = new Ajv({allErrors: true});
addFormats(ajv);

esm.sh even provides .d.ts definitions if available, so you can import types as well.

import Ajv, {ValidateFunction} from 'https://esm.sh/[email protected]';
const validate: ValidateFunction = new Ajv().compile(schema);

In some cases, you can even import the raw typescript file directly from git. But Ajv imports json files directly, which deno does not support atm.

Condense

To get latest version, just use browser address bar and strip version, like this: https://esm.sh/ajv, and it redirects to a later version if available – Chretien

Answer 2

You don't need an alternative, you can use ajv.

Ajv provides a bundle for browsers: https://cdnjs.cloudflare.com/ajax/libs/ajv/6.12.2/ajv.min.js

All you need to do is download it, save it to your project and add: export default Ajv at the bottom of the file.

ajv.js

/* ajv 6.12.2: Another JSON Schema Validator */
!function(e){if("object"==typeof exports&&"undefined"!=typeof module) /*....... */
//# sourceMappingURL=ajv.min.js.map

export default Ajv;

index.js

import Ajv from './ajv.js'

const ajv = new Ajv({allErrors: true});

const schema = {
  "properties": {
    "foo": { "type": "string" },
    "bar": { "type": "number", "maximum": 3 }
  }
};

function test(data) {
  const valid = validate(data);
  if (valid) console.log('Valid!');
  else console.log('Invalid: ' + ajv.errorsText(validate.errors));
}


const validate = ajv.compile(schema);

test({"foo": "abc", "bar": 2});
test({"foo": 2, "bar": 4});

---

Remember that Deno is a JavaScript runtime, so any code which uses plain JavaScript, you'll be able to use it with very little modification, in this case just export default Ajv

Imponderabilia

Also note that ajv has a type definitions file, raw.githubusercontent.com/ajv-validator/ajv/master/lib/ajv.d.ts, so you can get type checking and hints if you prefix the import statement with // @deno-types="https://raw.githubusercontent.com/ajv-validator/ajv/master/lib/ajv.d.ts" – Unbelievable

AJV seems to not work with Deno Deploy, due to it generating code. – Instantly

Answer 3

Till now, ajv-like schema validator is not available for Deno. However, you can try value_schema for schema validation. It has both Node.js and Deno versions.

Mcpherson

Do I understand correctly that value_schema/value-schema is not able to handle JSON schemas but implements it's own way of defining schemas? Is there some way to generate the value-schema code for a JSON schema? To what degree can value-schema even offer the capabilities of a JSON schema? – Dentistry

Answer 4

jtd is a viable alternative. It is a deno native implementation of JSON Type Definition, aka RFC 8927, which is an alternative to json-schema validation (and thus ajv) but has a similar purpose.

Mite