[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 https://github.com/hey-api/openapi-ts/discussions/1039#discussioncomment-11194255

[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.