[FeatureRequest] `transformer` for a custom `format`

[mrclrchtr]

I would like to define a transformer for a custom format and this should be applied when a string has this format:

e.g.

export class LocalTime {
  hour: number;
  minute: number;

  constructor(hour: number, minute: number) {
    this.hour = hour;
    this.minute = minute;
  }
}

      time:
          type: string
          format: time

then I would like to be able to parse this string into LocalTime.

Maybe, I could create my own plugin for this?

If this doesn't fit here, I'll open a separate topic or issue.

Originally posted by @mrclrchtr in #1039 (comment)

[mrlubos]

You'd also need to be able to transform the generated types, right? What would the appropriate type be in your example?

[mrclrchtr]

Unfortunately, I don't quite understand the question.

I'll try to explain my idea again:

• In the OpenAPI spec, I say that field has type: string and e.g. format: localTime (it's a custom format).
• In my WebApp I have defined the class LocalTime myself:

export class LocalTime {
  hour: number;
  minute: number;

  constructor(hour: string, minute: string) {
    this.hour = Number.parseInt(hour, 10);
    this.minute = Number.parseInt(minute, 10);
  }
}

• I tell HeyAPI that if a string has the format localTime, that it should use a special transformer to set the field in the generated types:

proposal:

{
	name: '@hey-api/transformers',
	custom: {
		type: string,
		format: localTime,
		parser: {
			regex: "/^([01]?\d|2[0-3]):([0-5]\d)(?::([0-5]\d))?$/", # For demo only
		},
		target: {
			pathToCass: "/calendar/LocalTime", # to be used for the import
			constructor: ["$1", "$2"]
		}
	}
},

then the parser would know how to parse the string and the transformer would know which elemento to set where in the constructor.

I just thought of that quickly... there is certainly a better API for this.