Ajv $async property cannot be set in the schema object

[dangrima90]

Hi again, been testing out the library together with Ajv asynchronous validations. Basically the idea is that certain form fields might need an API call to be validated further.

Example:

• Check if username/email is already in use
• Enough money in a user's account

According to Ajv's documentation this can be setup with the use of keywords and formats by using asynchronous functions that return a promise with a true / false value. (https://github.com/epoberezkin/ajv#asynchronous-validation)

When trying to set this up together with vue-form-json-schema I'm always getting this error:

[Vue warn]: Error in created hook: "Error: async format in sync schema".

Example code:

Schema

{
  type: 'object',
    $async: true,
    properties: {
    email: {
      type: 'string',
      format: 'checkIfExists'
    }
  }
}

Vue Form JSON Schema Options

{
  castToSchemaType: true,
  ajv: {
    options: {
      formats: {
        checkIfExists: {
          async: true,
          validate: (data) => new Promise ((resolve) => {
            // API call...
            // return Promise()
          })
        }
      }
    }
  }
}

I investigated the error and eventually found out that the issue is coming from the getVfjsValidationSchema getter. https://github.com/jarvelov/vue-form-json-schema/blob/96a0f64105b91c9bcdd7e4dff61b4918b6608b24/src/vfjs-global-mixin/methods/vfjs-validation/getters.js#L82

In here there's a "base" object schema, that sets the type and properties array but there doesn't seem to be anything related to $async.

Is this intentional as in something that is not supported on purpose, or is it a bug?

Thank you in advance!

[jarvelov]

Hi,

I've looked into it and this is a bug. However I do not yet know the scope of the bug. I'll investigate tonight and let you know what I find out.

[dangrima90]

Great thank you!

[jarvelov]

Okay, I've had a look, and unfortunately this isn't something I can fix until the next major version. I need to convert many synchronous functions to be asynchronous and this will break a lot of the internals which will introduce changes to the API.

I have wanted to rewrite to support async better for a long time and this issue will probably give me the push to dive into it, however this will take some time and I do not yet know when I'll be done with the rewrite. I have a list of things that I want to go into the next major version, which pushes back the release date further.

I want to provide this feature but I can't promise when it will be available, so the be frank: If you're evaluating different form libraries and this is a feature you need to support now, then I would recommend you to check out another library. If it is a 'maybe sometime in a month or so' then the chances are that I'll be able to provide a prerelease version you can try out, but I don't expect the next major version to be stable until sometime Q3 2020.

[dangrima90]

Thank you for the update. Will try to find another library as it is a feature that's needed now. Having said that, please do keep this issue updated, would like to know when this is available.