bcherny/json-schema-to-typescript

Support propertyNames with enum

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#337 opened on Sep 8, 2020

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enhancementhelp wanted

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Description

propertyNames is included in the "not expressible in TS" list, but at least for the case with enum instead of pattern, this is not true. Consider the following example:

{
  "type": "object",
  "title": "workingHours",
  "definitions": {
    "weekdays": {"type": "string", "enum": ["monday", "tuesday", "wednesday", "thursday", "friday", "saturday", "sunday"]}
  },
  "additionalProperties": {"type": "number"},
  "propertyNames": {"$ref": "#/definitions/weekdays"}
}

could well be expressed in TS as

enum weekdays {
  monday = "monday",
  tuesday = "tuesday",
  wednesday = "wednesday",
  thursday = "thursday",
  friday = "friday",
  saturday = "saturday",
  sunday = "sunday"
}
type workingHours = {[k in weekdays]: number};

The example also shows what would be the purpose of this instead of specifying the properties literally: weekdays does not have to be repeated all the time when there are more types making use of its keys.

Contributor guide

Research direction
Investigate the current implementation of propertyNames in the codebase, specifically how pattern based propertyNames are handled. Then extend to support enum based propertyNames by generating a mapped type over the enum keys.
Tech stack
typescript
Domain
tooling
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
TypeScriptJSON Schema
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65