Enable $data reference usage for AJV validation

[nitishdhar]

Prerequisites

• I have read the documentation;

Description

Looking at the docs for AJV, it enables us to write validation rules using $data reference to an existing schema field's value, like

var ajv = new Ajv({$data: true});

var schema = {
  "properties": {
    "smaller": {
      "type": "number",
      "maximum": { "$data": "1/larger" }
    },
    "larger": { "type": "number" }
  }
};

var validData = {
  smaller: 5,
  larger: 7
};

ajv.validate(schema, validData); // true

But the default setup for AJV in RJSF does not enable $data=true

Is this an opinionated design choice for some reason or we can somehow enable it. I couldn't find documentation that lets us override the AJV setup.

Having the $data reference will enable us to write more complex schema based validations.

Is this something you will be open to enabling or letting users override this option somehow?

Thanks

[epicfaace]

I'm open to enabling this! This library was initially created without AJV, so not all the possible features of AJV were enabled by default. Please make a PR and I'll take a look.

[nitishdhar]

Thanks.

I will start working on a PR to enable $data reference.

Meanwhile, can you also share your thoughts on adding a new dependency to ajv-keywords.

This will enable the proposed keywords switch, patternRequired, formatMaximum / formatMinimum and formatExclusiveMaximum / formatExclusiveMinimum from JSON Schema extension proposals allowing us to do format based comparisons during validation. e.g. Defining schema validation to validate if a date should be minimum of another date attribute in the schema -

startDate: {
  type: "string",
  format: "date",
  title: "Start Date",
},
endDate: {
  type: "string",
  format: "date",
  title: "End Date",
  formatMinimum: {
    "$data": "1/startDate"
  }
}

If this makes sense, I will make this part of the PR.

[epicfaace]

Great, thanks!

Meanwhile, can you also share your thoughts on adding a new dependency to ajv-keywords.

Hmm, I'd be wary of adding in keywords that are not yet part of the JSON schema specification. For example, the ajv-keywords repository mentions that switch is deprecated and they suggest using if/then/else, which is part of the spec instead.

I'd be open to adding in functionality that is part of the JSON schema spec such as if/then/else (see #885 and #916), but otherwise it might take only a very good reason to add in additional keywords that are not part of the spec.

[epicfaace]

Actually, given that $data is not yet part of the JSON Schema spec (it's just a proposal as of now -- see json-schema-org/json-schema-spec#51), it might be better to wait until we see if and/or how it is incorporated into the JSON schema spec before implementing it in rjsf.

[charlysotelo]

I could use this feature pls

[epicfaace]

Closing this issue -- can reopen if json-schema-org/json-schema-spec#51 is accepted

[zeddotes]

Hey, I've created a fix for this waiting to be approved by the team: #1668